ALBERT

Description: 1. A small-scale plot experiment which had been conducted from 1947 to 1952 to study the effect of massive dressings of fertilizer nitrogen, with and without phosphate and potash, on the yield and quality of a rye-grass dominant sward was continued from 1953 to 1958 with two changes in the mineral treatments in 1953. A 4 × 4 Graeco-Latin square was used.The nitrogen treatments applied each year were: (1) no nitrogenous fertilizer, (2) 260 lb. nitrogen, (3) 520 lb. nitrogen and (4) 416 lb. nitrogen per acre per year.The mineral treatments were: (A) no mineral fertilizer, (B) 336–504 lb. K2O per acre per year depending on nitrogen treatment, (C) 101–202 lb. K2O and 81–101 lb. P2O5 per acre per year depending on nitrogen treatment, and (D) no mineral fertilizer after 1953, although K2O and P2O5 had been applied during the previous 6-year period.All the fertilizers were applied in four or five equal dressings each year, one for each cut.Treatments 1 and 4 were cut four times and treatments 2 and 3 five times per year.2. Applications of phosphate did not affect the yields of herbage dry matter or crude protein, but yields were severely depressed in the absence of potash. With adequate potash the yields under all nitrogen treatments were maintained for the 6-year period and were at the same level as in the previous 6-year period. The mean yields of dry matter for the 6-year period when potash was applied were 5200, 8420, 10,180 and 9700 lb. per acre per year for treatments, 1, 2, 3 and 4. Without potash the corresponding mean yields were 5460, 6410, 6210 and 6880 lb. Average crude protein yields were 760, 1360, 1940 and 1660 lb. per acre per year with potash and 780, 1100, 1220 and 13201b. without potash.3. The weighted mean contents of crude protein for the 6-year period averaged over all the mineral treatments were 14·4, 16·7, 19·4 and 18·2% for nitrogen treatments 1, 2, 3 and 4. The mean crudeprotein contents of treatments with and without potash were 16·7 and 17·6%, respectively.4. The average response to nitrogen was 15·0, 10·9 and 12·4 lb. dry matter per 1 lb. of nitrogen applied on treatments 2, 3 and 4, respectively, compared with a no-clover sward, and 7·8, 7·3 and 7·9 lb. compared with a grass + clover sward. The recovery of nitrogen in terms of crude protein was 45, 40 and 40% for treatments 2, 3 and 4, respectively, when compared with a no-clover sward.5. The botanical composition of the plots continued to be determined by the nitrogen and potash treatments. On plots receiving ‘Nitro-Chalk’ clover was virtually non-existent, whereas on plots which received potash and no nitrogen, clover was present. With a combination of potash and nitrogen vigorous swards of timothy were found but if only nitrogen and no potash was applied, poorer grasses, such as Festuca rubra, were dominant.6. Soil analyses showed increased pH values and decreased contents of Mg with increasing applications of ‘Nitro-Chalk’. P2O5 values were low except where phosphate was being applied. The most marked change was in the K2O values which varied from 4 units on treatments A and D which received no minerals to 40 units on treatment B which received the heavy dressings of potash.7. Mineral analyses of the herbage for 1953 and 1958 are given. High K contents were found on treatments where potash was applied and this was associated with decreased Mg and Na contents.8. Some details are given of a field-scale trial on the Institute farm where high levels of nitrogen and potash have been applied for 11 and 12 years with successful results.

Description: 1. Three trials are reported in which the grazing behaviour of separate groups of cows, one receiving supplementary food, either as conserved roughage, concentrate or fodder crop, was observed over 24 hr. periods. A fourth trial, assessing the effect of summer temperatures on unshaded milking cows, is briefly described.2. In trials 1 and 2 the stall feeding of either conserved roughage or concentrate reduced grazing as compared with unsupplemented cows by approximately 10%.3. Allowing access to a fresh ‘strip’ of a fodder crop at a set time each day, whilst not altering total grazing time, very markedly altered periodicity of grazing. Cows delayed grazing up to 3 hr. whilst awaiting a fresh ‘strip’.4. Environmental temperatures up to 87° F. did not alter total grazing time as compared with grazing time when temperature reached a maximum of only 70° F.5. The value of supplementary feeding of dairy cattle at pasture, at least where the intake of pasture is sufficient for maintenance and a low level of production, appears to be open to question.

Description: An insignificant short-term increase in the natural dose of ionizing radiation during the embryogenesis period is beneficial not only for the embryonic development of the chicks, but also for their postembryonic growth and development as well as the egg production of the pullets.Irradiation of incubated eggs with microdoses of radioactive radiations is another possibility for the utilization of atomic energy bringing about an improvement in the economically useful properties of poultry.

Description: An artificial rumen is described which has been shown to simulate closely conditions in the bovine rumen. Criteria of its validity include quantitative and qualitative bacteriological data, V.F.A. production, pH levels and digestion rates; these were examined with a variety of diets using cows on similar diets as controls. An important feature of the apparatus is the high degree of control which can be exercised over the progress of the in vitro ruminal fermentation, permitting experiments of considerable duration.

Description: 1. The potency of balancing interactions between the protein of herring press-cake (dried) and solubles (condensed) on one side, and certain vegetable feeds on the other, has been examined on 2- to 4-week-old chicks:(a) Initially by comparing the co-effect of a series of different combinations of the herring products when ingested together with certain cereals plus extracted ground-nut meal, to that estimated earlier when the same combinations of herring products formed the sole dietary protein.(b) Thereafter by studying whether the co-effect of the herring products was influenced or not by substituting extracted soya-bean meal for the ground-nut meal.(c) Further by tentative trials to show that registered interactions were caused by some keystone amino acids.2. A special dietary system was devised for the purpose (a basal diet of actual feeds + a synthetic, practically protein-free basal diet + the tested feed, eventually + adjustments), the results being recorded as combinative protein value = c.p.v.3. Interactions between dietary constituents not only were shown under the circumstances, but proved to be an easily acting factor of great power. Herring solubles in proportions of 15–45% were formerly found to bring about a statistically significant improvement of the meal when fed together with this as the only protein of the diet. But: (a) the introduction of certain cereals and ground-nut readily converted the beneficial effect of the solubles into a significantly negative one. (b) Whereas soya-beans instead of ground-nut evidently reversed the situation again. In this third grouping solubles at moderate levels appeared neutral, meaning that herring solubles combined significantly better with soya-bean than with ground-nut when fed to young chicks in presence of a set of cereals and herring meal, (c) Responses to supplemental, crystalline amino acids showed that the interactions between the protein sources could be attributed to their constituent amino acids. Thus the little efficient combination of solubles and ground-nut plus certain cereals could be greatly improved by small quantities of all ten essential amino acids together, and equally much by lysine plus threonine only. Contrarily, the diet appeared weakened when lysine, threonine or isoloucine were omitted singly or together from the whole ten. The same was the case with single addition of leucine.4. The discussion stresses the pre-eminent importance of the diet in biological estimations of protein value. It also points out the practical significance of skilful combination of different protein sources.

Description: 1. A study was made of the effects of diet on the growth of the internal organs, and in particular the four stomachs of lambs.2. A total of twenty-three lambs was reared from birth on various diets ranging from all milk to small amounts of milk and roughage ad lib. The lambs were slaughtered at various ages and the fresh wet weights of the parts of the alimentary tract and the other internal organs were recorded.3. The growth rates of the four stomachs were influenced by the plane of nutrition, however, the type rather than the plane of nutrition was more important in determining the weights of the stomachs relative to each other and to live weight.4. Lambs fed solely milk from birth had the development of their fore-stomachs retarded at about the level found in the 3-week-old grazing lamb. The abomasums of these lambs were abnormally heavy.5. The rumens and reticulums, which were retarded in their growth by milk feeding, reached normal proportions very quickly once roughage was fed.

Description: The present work extends the information on the skin thickness of cattle and shows that generalizations made in previous work were only partly correct, for there are significant differences only between the skin thickness of the Zebu ‘races’ of tropical cattle and Bos taurus.Again there appeared to be no significant difference between animals of different ages within breeds.The work confirmed that cattle of eleven tropical breeds comprising four of the major ‘races’ of African indigenous cattle have a significantly thinner papillary layer than temperate breeds, and this was very strongly correlated with their superior heat toleration.Further support based on wider premises was therefore given to suggestions made by Dowling regarding the importance of the histology of the skin in heat toleration.

Description: Two early weaning experiments are reported. When grazing young, high protein pastures, lambs weaned at 7, 10, 13 and 18 weeks of age grew equally well and there were no significant differences between their carcass weights, grades, and dressing percentages.However, when grazing pastures in the preflowering and flowering stages of growth, lambs weaned at 8 weeks of age did not grow as well as unweaned controls. Their carcass weights, grades, and dressing percentages were also inferior. It is suggested that these differences were primarily due to an inadequate protein intake.No difference in wool production was found either between the ewes of early weaned and control lambs, or between the lambs themselves.

Description: 1. Ten manurial treatments were applied annually to cattle cabbage grown in a six-course rotation for 7 years. Samples were taken in the early winter each year, and from five harvests taken at fortnightly intervals in the last year.2. The dry-matter yields each year closely followed the weather conditions during the growing season. There was no significant fall in the dry-matter yield during the last season. The treatments supplying phosphorus or phosphorus and potassium substantially increased yield, but the application of nitrogen did not.3. The application of nitrogen, potassium or phosphorus increased the levels of these constituents in the crop in practically all cases. The application of phosphorus produced hearted plants which contained significantly less dry matter than the openleavod plants produced in its absence. The levels of ether extract, crude fibre, ash, silica and magnesium wore not significantly affected by the manorial treatments.4. There was little variation in composition as the season advanced except for significant increases in the crude-fibre levels and decreases in the nitrogen-free extractives levels.5. The distribution of the chemical components was investigated in the outer leaves, heart leaves and stem of the plant. This was compared with that in the marrow-stem kales.6. The chemical composition of the cattle cabbage compares fairly closely with that found for the marrow-stem kales grown under similar conditions. It is, however, lower in dry matter, crude fibre, magnesium and chlorine. It may be considered as a replacement for marrow-stem kale as a source of crude protein and all the major minerals except chlorine and possibly magnesium.

Description: Two calves (Zebu × Australian Illawara Shorthorn and Shorthorn) of about 7–8 months of age were exposed to controlled atmospheric conditions. Cutaneous evaporation from the shoulder and belly areas of these calves was measured by the capsule method. Density of the sweat glands in the shoulder and belly areas of these calves was measured, using a biopsy punch. Density was estimated by counting the hair follicles.(1) The Zebu cross sweats more than the Shorthorn, at least from the shoulder area, and this is related to its higher sweat gland density as compared with that of the Shorthorn.(2) In the Zebu cross cutaneous evaporation from the shoulder area is greater than that of the belly and this is associated with the differences in the number of sweat glands.(3) In the Shorthorn cutaneous evaporation is the same from both shoulder and belly areas and the number of sweat glands in these regions is also the same.

Description: 1. The digestibilities of the protein, oil and carbohydrate by chick in mash and pellets made from this mash have been determined at weekly intervals from 0 to 9 weeks.2. There was no difference in the chemical composition of the food due to pelleting, not were there any differences in the digestibilities due either to pelleting or the age of the chick.

Description: 1. The excretion of 144Ce in the faeces, urine and milk has been followed in two dairy cows receiving twice daily doses of 120 μc. with the feed over a 10-day experimental period. During the terminal 3 days, recoveries from the faeces amounted to 93–119% of the daily dose. From the urine and milk, respectively, 0·23 and 0·17% and 0010 and 0·016% of the total amount fed was recovered from the two animals.2. The concentration of 144Ce in various parts of the gut was estimated after equilibrium conditions had been attained. The highest concentrations were found in the contents of the omasum and hind-gut.3. The possible use of 144Ce as a marker in digestibility and similar trials is discussed.

Description: 1. The normal level of blood ammonia in the sheep seems to be somewhat higher than in nonruminants.2. The toxicity of ammonium acetate, ammonium chloride or urea placed in the rumen follows different metabolic pathways. In the case of the chloride there is an uncomplicated metabolic acidosis which is not, however, adequate to account for the toxic symptoms. When the acetate is administered there is also a respiratory alkalosis and in the presence of urea the changes in the acid-base status, though interesting, do not account for the toxicity.3. The toxicity is almost certainly due finally to a direct effect of the circulating ammonium ion level though in the case of urea, there is an earlier effect that may be of a pharmacological type and is less severe.4. The organisms within the rumen rapidly reach a maximum level of adaptation (7 days) to handle large quantities of ammonia by a synthetic pathway.5. The intravenous administration of L-arginine did not markedly ameliorate the ammonia toxicity.

Description: 1. The oxygen consumption of young pigs from 1 to 37 days of age has been measured in a closed circuit respiratory metabolism chamber, over the environmental temperature range 4–37° C.2. The values obtained for single pigs alone in the chamber have been compared with the results of measurements on groups of pigs 3–6 days of age taken together.3. It has been found that as environmental temperature falls below 30° C. and the grouped pigs huddle together, oxygen consumption per kg. for the group becomes smaller than values for single pigs of the same individual weight, and corresponds more with results from the larger single pig.4. Rectal temperature is maintained in pigs of the group at a lower energy cost than that required for the single pig, the saving in energy expenditure becoming proportionately greater as ambient temperature falls.5. These results are discussed in relation to body size and skin temperature.

Description: 1. Three levels of a nitrogenous fertilizer, supplying 0,104 and 208 lb. N per acre were applied in 1955 and 1956 to a rye-grass/white clover sward in its fourth and fifth harvest years on a loam soil overlying chalk.2. Levels of animal production were measured using fattening cattle maintained on the plots at a stocking rate of 1⅓ per acre: excess herbage was conserved and fed back to them later.3. Low rainfall in 1955 seriously affected yields of herbage and response to fertilizer, and severely reduced the clover content in all treatments.4. Rate of live-weight gain per head was not reduced by the application of fertilizer at either level. Vigour of the sward was maintained by fertilizer application in a dry spring period in 1956, whereas, in the control treatment, which was low in clover, gains per head were markedly reduced because of inadequate dry-matter production.5. By applying two-thirds of the fertilizer in late summer, a considerable extension of grazing time was obtained, particularly when rainfall was adequate. At the highest level of fertilizer application in 1956 the grazing season was extended from 6 months to 7½, and the cattle continued on conserved feed to a total of 8½ months. Response to the medium and high levels of application on grazed herbage only was 12 and 15 bullock-days per acre, respectively, in 1955. In 1956 the response was 46, and 67/59 (the two high nitrogen treatments). In terms of total live-weight gain per acre the response in 1955 to medium and high levels was 23 and 32% above control, up to 427 lb. per acre: in 1956 it rose to 51 and 52/55% with the highest treatment reaching 657 lb. per acre. Greater financial returns than are indicated by live-weight gain should result from the rising price per pound of carcass as the supply of fresh beef dwindles in early winter.6. Carcass data indicated that both greater rate of gain and the extra time spent on fertilized herbage and conserved feed increased carcass weight and maturity in the normal pattern of development, fat most rapidly, muscle next and bone least. No significant differences in conformation due to treatment was detected by analysis of grouped joints.

Description: 1. Twenty-two experiments on main-crop potatoes in 1955–7 compared calcium nitrate and ammonium sulphate applied to the seedbeds before planting. Urea was also tested in fifteen of the experiments in 1956–7. The three fertilizers were compared at rates that supplied 0·5, 1·Oand 1·5 cwt. N/acre.2. Seven experiments on kale in 1955–8 compared seedbed dressings of calcium nitrate and ammonium sulphate. Urea “was also tested in. five of the experiments in 1956–8. The rates used were 0·6, 1·2 and 1·8 cwt. N/acre in 1955 and 1·0 and 2·0 cwt. N/acre subsequently. Single dressings applied to the seedbed were also compared with divided dressings applied partly to the seedbed and partly in mid-season.3. Generally the potatoes gave only small responses to N; there was no worthwhile gain from applying more than 1·0 cwt. N/acre in 1955 and 0·5 cwt. N in 1956 and 1957. Nitrogen gave much larger proportionate increases in yields of kale, at several of the centres crops continued to respond up to dressings of 2·0 cwt. N/acre.4. Calcium nitrate generally gave lower yields of potatoes than ammonium sulphate and the superiority of ammonium sulphate was greater with the higher dressings. Losses in yield with the nitrate were usually associated with a severe check to early growth occurring in dry springs and with dressings concentrated close to the seed, but lower yields were also obtained at some centres where early growth was not damaged. Calcium nitrate and ammonium sulphate were roughly equivalent for kale when the nitrate did not damage germination; heavy seedbed dressings of the nitrate reduced kale plant numbers severely unless there was adequate rain after sowing.5. Granulated urea tested in 1956 contained 4·5% of biuret, it delayed emergence and reduced plant establishment seriously in several of the potato experiments; damage increased with the level of manuring and was accentuated when dressings were broadcast over furrows before hand-planting. Yields given by this batch of urea were less than with other N fertilizers and when 1·5 cwt. N/acre was applied they were less than with no nitrogen at all. Purer crystalline urea (having less than 1% of biuret) used in the 1957 experiments caused no damage to emergence of potatoes and gave yields similar to those obtained with ammonium sulphate. There were similar effects in the kale experiments; granulated urea containing much biuret damaged germination severely in 1956; the purer products containing little biuret used in later years reduced plant numbers at one centre in 1957 and at the single 1958 centre. Where there was no damage to the establishment of kale, urea and ammonium sulphate gave similar yields.6. Dressings applied partly to the seedbed and partly in mid-season gave slightly higher average yields of kale than an equivalent total amount of nitrogen all applied before sowing.

Description: 1. There were many distinct, consistent, individual differences in the thyroid activity of several of the animals used in this study. Graphic indications of breed differences were present at several high temperatures, and statistical analyses supported differences between the Jerseys raised at each temperature and the other two corresponding breeds. The Jerseys displayed higher rates. In no instances were there thyroid 131I release rate differences between Holsteins and Brown Swiss.2. There was a negative correlation between thyroid 131I release rate and temperature for each breed raised at each temperature. Correlations for the 50° F. animals were statistically significant below the 0·05 level of probability and for the 80° F. animals they were significant below the 0·01 level. As the environmental temperature increased from 35° to 80° F. there was a gradual decrease in thyroid 131I release rate. Above 80° F. there was a sharp decline in thyroid 131I activity.3. Within the range of environmental temperatures from 35° to 70° F. the animals raised at 80° F. displayed thyroid release rates higher than those of the animals raised at 50° F. At 80° and 90° F. the 50° F. Jerseys exhibited higher activity. The Jersey differences approached statistical significance. At the lower temperatures graphic differences between the Brown Swiss and the Holsteins raised at the two temperatures appeared to be present, but they were not generally supported by statistical analysis.4. At temperatures of 80° F. and above, when regulatory mechanisms could not control body temperature, both groups showed considerable rises in body temperature concomitant with decreases in thyroid 131I activity and TDN consumption. The 80° F. group showed a rise less sharp than that of the 50° F. group.

Description: The average yields of irrigated long-staple cotton in the three-course rotations: dura, fallow, cotton, D-F-C; lubia, fallow, cotton, L-F-C; and fallow, fallow, cotton, F-F-C, were studied over 12 years in an experiment in the Sudan Gezira; the fallows (resting land) were either hoed or were left uncultivated during the rainy season, so that the effects of the operation of hoeing on the subsequent cotton yields could be measured.Where the fallows were unhoed L-F-C yielded more cotton than F-F-C, which gave at first higher yields than D-F-C, although this difference had disappeared by the end of the period. Fallow hoeing increased yields in all rotations; this response was maintained in D-F-C and L-F-C. In F-F-C the response to hoeing either fallow diminished steadily in time and whilst the higher response to hoeing both fallows also decreased, its rate of decrease was no greater than when only one fallow was hoed. The response to hoeing fluctuated considerably from year to year. In all rotations these fluctuations were associated with rainfall and the relationships have been expressed in the form of regression equations; separate equations were necessary for each rotation as the relationships were quite distinct.The variety X1730 A out-yielded Domains Sakel. There were interactions between the varieties and the other treatments, but these interactions were such that the varieties differed more at higher levels of yield and did not modify the above conclusions appreciably.

Description: 1. The penises of five bull calves were examined during the first year of life, using epidural anaesthesia or sedation with chlorpromazine hydrochloride.2. The process of separation between penis and sheath is described and data on age and weight of the calves are given.3. There was considerable variation in times and rates of development, but in general terms the penis began to separate from the sheath at about 4 months of age, and the process was completed at about 10 months.4. From the second to the sixth or seventh month of life the penises of these calves were short, and not manually protrusible.

Description: Phosphate responses of wheat in a number of soil types have been correlated with the amounts of phosphate extracted by ten different methods. Of these only total organic phosphorus, and inorganic phosphorus extracted with hot 0·1N caustic soda, were significantly related to phosphate response, the former at the 1% level and the latter at the 5% level. The amount of organic phosphorus in the soil was also found to be significantly related, in each instance at the 5% level, to phosphate responses of grass and the percentage phosphate in the grass. When the amount of organic phosphorus was considered together with the phosphate retention capacity of the soil, to give a measure of available mineralized phosphate, the relationships to response (and uptake of phosphorus by grasses) was more significant than with organic phosphorus alone.The organic phosphorus fraction accounted for about 86% of the total soil phosphorus. Measurable amounts of water-soluble organic phosphorus were found with all the soils. The amounts were, however, not significantly related to phosphate response. Moreover, it was found that while the soil extract containing organic phosphorus decomposed, it did so without the production of mineral phosphate. From this, and further evidence in the literature, it is considered that the organic complex in the soil, rather than the water soluble phosphorus, is the main source for the plant.

Description: 1. The crude protein requirement of goats for maintenance has been determined from balance studies. The requirement per kg., as found by three different methods of treatments of the balance data, is practically the same, viz. 2·63 g. crude protein.2. The digestible crude protein requirement also has been calculated, again by two different methods, and is estimated at 1·12 lb./1000 lb. body weight. This value is undoubtedly very much higher than the value (0·65 lb./1000 lb.) obtained previously from the endogenous urinary nitrogen determinations alone.3. The dry-matter requirement of goat per 100 lb. live weight has been determined. Calculated on the basis of live weight raised to the power 0·734, the requirement was found to be 2·6 lb./100 lb.

Description: 1. EUN and MFN excretions have been determined in goats on a N-low ration and also on a N-free ration. The values obtained were,EUN = 0·052 g./kg. live weight andMFN = 0·41 g./100 g. dry-matter feed intake.2. The values so determined with the two feeding regimens, for both the EUN and MFN agreed very closely.3. The minimum protein requirement of goats for maintenance, as calculated from the EUN value, is 0·65 lb./1000 lb. live weight.4. The formula for calculating the utilizable protein requirement for this species is found to be P = 0·89. W0.734, and is almost identical with the one given by Mitchell.5. The usefulness of the above formula in predicting the EUN of immature goats is discussed.

Description: In a cross-breeding experiment involving all types of matings among Friesian, Ayrshire and Jersey cattle, the effect of maternal size has been investigated, based on various comparisons of reciprocal crosses, using data on weight and body size from birth to 2 years of age. Among the thirteen characters analysed, there was a close relationship at I month old between the relative maturity of the characters and the relative extent of their maternal effects. This relationship showed that the more mature characters were the least affected by the maternal environment. Cross-bred calves out of a mother of the larger breed were larger at birth than the reciprocal crosses but in all cases this difference disappeared during the first year's growth.The early expression of the offspring's genotype for body size depended on whether prenatal growth had been favoured or restricted by the maternal environment within limits. Maternal retardation of growth resulted in neonatal phenotypes closely related to their genetic ranking for mature body size, whereas early expression of the genotype is obscured by lavish prenatal conditions.A mammalian growth model is presented and the results are interpreted in terms of this model. The explanation assumes that temporary advantage is taken, during growth, of variations in the environment, when the latter exceeds a minimal level demanded by the genotype for stable development to normal mature size. This supply and demand hypothesis of growth is discussed in terms of its implications for genetic selection of different types of body characters. The main conclusion is that an understanding of the early environment, particularly the maternal one, may permit selection for some adult characteristics to be carried out at an early age.

Description: 1. Statistics of several measured parameters are reported. They show that fermentation rates of rumen contents from zebu and European-type cattle in East Africa differ due to time of feeding, to individual animals, and to differences between zebu and grade.2. The fermentation products were determined as acid, CO2 and methane. The proportion of methane showed an inverse correlation with the rate of fermentation.3. The mean fermentation rate showed a trend in the direction expected from the weight gains of the animals.

Description: 1. Two series of simple nitrogen manuring trials, one on level of sulphate of ammonia applied to the seedbed at twenty-two centres and the other on the time of top dressing with ‘Nitro-Chalk’ at nineteen centres, were conducted on commercial farms in south-east Scotland during 1954 to 1957.2. The optimum level of sulphate of ammonia varied with season and farm type. The optimum dressing was at least 0·9 cwt. N/acre in the dry season of 1955, and in the other years was estimated to be 0·9 cwt. N/acre on arable farms and about 0·-25–0·4 cwt. on ley rotation farms when the barley did not follow sheeped turnips. In the latter event no fertilizer was best.3. The nitrogen content of the grain increased little until after the 1 cwt. sulphate of ammonia level, although the optimum yield was not obtained in many experiments without some rise in the grain nitrogen content.

Description: 1. A factorial experiment on wether hoggs was carried out to examine the effects on bone growth and composition and on blood composition of four dietary factors. The factors were extra calcium, phosphorus, vitamin D, and energy in the form of starch, and each was fed in all possible combinations, so that there were sixteen dietary treatment groups in all. Each group consisted of three animals.2. Serum calcium and blood inorganic phosphorus concentrations were determined monthly, and radiographs of most parts of the skeleton were taken at the beginning and end of the experiment. After about 6 months on the experimental diets the animals were killed and the ash weights and percentage of ash of different parts of the skeleton and of the whole skeleton were determined. Live-weight changes and food intakes were also measured.

Description: 1. The mean velocity ῡ and the velocity frequency distribution f(υ) of bull spermatozoa with normal motility have been determined in standardized eggyolk—citrate buffers at different pH values, ranging frompH 5·70 to 8·35.Under assumed approximately anaerobic conditions at37·0 ± 0·1° C. the mean velocity was found to show a straight-line relationship -with pH in the physiological region pH 5·70–7·50, according to the general equationStatistically, k was shown to be a linear function of a, namely,Consequently, the dependence of the mean velocity of the spermatozoa from any ejaculate can be characterized by the one parameter a = dῡ/dpH. (dimension μ/sec./pH), determining the slope of the ῡ υs. pH curve.The mean velocity of all individual spermatozoa (measurements of all ejaculates at the same pH value pooled together) could be described accurately by the equation:For some ejaculates the linear relationship was found to hold up to pH 8·00.2. The velocity frequency distribution curves were found to change with pH. At pH 5·70 the curves are skew with a relatively high top value. At increasing pH values both the top value and skewness decrease. The mean standard deviation of the velocity distribution f(υ) was found to be proportional to pH and could be described by the equationThis means that the variability in swimming speeds of the individual spermatozoa of any ejaculate increases proportionally with pH, indicating a strain effect of increasing alkalinity on the population, irrespective of the general stimulation of motility in the region up to pH 7·50.3. At each pH value the mean velocity decreases with time. Under assumed approximately anaerobic conditions at 37° C. the speed of velocity decrease as a function of pH was found to differ so much between different ejaculates that no generalization could be derived from the available material. The same holds for the effect of pH on the number of normally moving spermatozoa in the diluted ejaculate.4. The total number of spermatozoa moving normally depends on pH, but the optimum varies with the individual ejaculates.

Description: The beneficial effect on the nutritive value of bread and similar cereals of adding small amounts of lysine and other essential amino acids has recently aroused considerable interest both in Great Britain and in America. Tests carried out with rats have shown considerably improved growth rates accompanied by increased efficiency of food conversion.

Description: Swarm preparations are leas frequent (at least during July and August in southern England) among colonies with queens reared in the current year than among those with queens of the previous year (Simpson, 1957). Queens which had survived one and two winters are now considered; they are described as 1- and 2-year-old, respectively.

Description: A field experiment was carried out to study the effect on spring oats of undersowing with broad red clover, Italian rye-grass and a mixture of both. Two levels of nitrogen were used, namely, no nitrogen and 3 cwt. per acre of ‘Nitro-Chalk’.1. Oat shoot weight was reduced by undersowing, Italian rye-grass having a greater effect than red clover, particularly where nitrogen was applied.2. In the absence of nitrogenous fertilizer undersowing did not reduce oat plant height, but where nitrogen had been given, Italian rye-grass either alone or in a mixture with the clover, reduced the height; the legume alone had no effect.3. Undersowing generally reduced the number of oat panicles. Italian rye-grass had no effect when nitrogen was not applied, but a marked reduction was observed when nitrogen was applied. The legume had the greater influence where nitrogen was not applied.4. Red clover increased the number of whorls, and the number of single-grained spikelets per panicle. Grass sown alone or with clover reduced the number of single-grained spikelets per head.5. The total number of grains per panicle, 1000 grain weight, percentage husk and the percentage of saleable grain were not influenced by undersowing.6. No lodging occurred but there was an indication that resistance to bending of the straw was affected by undersowing with Italian rye-grass.7. Seeding herbage under the oats had a bigger influence on the yield of straw than grain. Italian rye-grass sown alone or with clover reduced the yield of straw where nitrogen had been applied. The legume alone had no effect. Grain yields showed a similar trend.8. Yield and percentage crude protein in the straw were reduced by Italian rye-grass alone or in a mixture with clover when nitrogen was applied, but there was no effect where nitrogen was withheld. The grass had a greater effect than red clover while a mixture of both was intermediate to the legume and grass sown separately. Italian rye-grass greatly reduced the recovery of applied nitrogen by the cereal.9. The percentage moisture in the oat sheaves was increased by undersown herbage and red clover had a bigger influence than the grass. The application of nitrogen reduced the bulk of clover under the cereal and its adverse influence on the harvesting of the oats. In the absence of undersowing, nitrogen had no effect on the percentage moisture in the sheaves.

Description: 1. The ratios of water drunk:hay eaten were studied for groups of Zebu and grade Hereford steers.2. In all comparable conditions the ratio was significantly smaller for the Zebus.3. Restricting water availability to about half significantly reduced the ratios for both types of steers.4. The decrease in hay eaten resulting from restriction of water was less for the Zebus.5. Restricting the hay intake to approximately half significantly increased the ratios for both groups.6. The Zebus drank significantly less water than did the grades in relation to body weight.7. It is concluded that the results of water restriction may not be as disastrous as would have appeared likely from the constant ratio relationship of water and food intakes previously suggested, particularly in the case of the Zebu steers who have been shown to be better adapted to dry conditions.

Description: Studies have been made on calcium and inorganic phosphorus in pasture grass and their relationship to blood levels in Zebu cattle.Excitement, adrenaline injections and fatigue were investigated as possible causes of variations in the inorganic-phosphorus levels of the blood of Zebu cattle.Sudden rainfall appeared to cause alterations in the inorganic phosphorus levels of blood. This hypothesis, when tested on two separate batches of cattle on two occasions, showed that there was a highly significant relationship between water intake and the level of inorganic phosphorus of Zebu cattle blood.Water starvation caused a steady increase in the level of inorganic phosphorus and when water was available for the cattle to drink the inorganic phosphorus level fell rapidly to a subnormal level before returning to normal. These results are discussed in the light of the available literature.

Description: 1. The live-weight gains and food consumption of groups of chickens subjected to two different patterns, (A) and (B), of allocation of a restricted quantity of food, were compared with the live-weight gains and food consumption of a control group (C), fed ad lib. throughout the experiment.2. Group B (compensatory growth regime), showed a greater relative growth rate after re-alimentation than group A (mild restriction followed by ad lib. feeding). The growth rate of group B was shown to be significantly greater than that of the control group at equivalent live weights. In addition, it was shown that the increased growth rate, induced by periods of restriction of similar severity and duration, was very similar for birds within the ranges of 200–300 g. live weight and 750–1100 g. live weight.3. The differences, due to treatment, in the growth rate after re-alimentation were in part caused by a concurrent increase in appetite. The severity and duration of the undernutrition immediately prior to re-alimentation would appear to affect appetite during re-alimentation more than the total restriction imposed. Measured in terms of food consumed, the restriction imposed upon groups A and B was the same, but in terms of live weight gain group B was very slightly more retarded than group A.

Description: An experiment on the use of wheat straw (ploughed in or composted at the rate of 53⅓ cwt./acre every second year) and NPK fertilizers in the maintenance of fertility was carried out at Rothamsted between 1933 and 1958. The effects of these treatments on the yields of the crops of the rotation used in the experiment—barley, sugar beet, potatoes—are discussed in the present paper.The treatments appear to have had no effect on crop yields through improvements to the soil caused by better structure or increased organic matter content. All the effects obtained can be attributed to changes in the supplies of available nutrients. The most important of these changes appear to have been: (1) nitrogen deficiencies due to the immobilization of soil nitrogen or nitrogen fertilizer by the straw: there is some evidence that this added to the store of slowly available nitrogen; (2) additions to potassium supplies from potassium in the straw. Factor (1) affected all three crops. Factor (2) affected potatoes, the only crop of the three to give good responses to potassium.It was found that when the straw was ploughed in directly about 0·08 ewt. N fertilizer applied to the crops for each ton of straw was sufficient to overcome losses in yield due to nitrogen deficiencies. The straw improved the yields of potatoes in the first and second years after application. Provided that allowance was made for losses of available nitrogen the yields of potatoes from ploughed-in straw were about the same as the yields obtained by adding K fertilizer to the crop, equal in amount to the potassium in the straw. When part of the fertilizers was ploughed in with the straw instead of being given directly to the crop the yields of potatoes were reduced.Compost made with NT fertilizers and straw and ploughed in with K fertilizer gave much poorer yields than were obtained by ploughing the straw in directly and applying the fertilizers to the crops. Losses of available nitrogen were severe, all the N fertilizer used in making the compost (0·15 cwt. N for each ton of straw) being either lost through drainage or immobilized by the straw. In addition, more than one half of the potassium in the straw was lost in composting.There was no evidence that any of the nitrogen immobilized in the decomposition of the straw became available in the first or second years after application. Residues from repeated applications of straw every second year over 18 years increased the yields of potatoes and sugar beet in the last 6 years of the experiment. The increases may have been due to the release of previously immobilized nitrogen.

Description: 1. Thirty-two single lambs were grazed together on pasture. At weekly intervals, from birth to 112 days of age, two lambs were slaughtered and various organs weighed immediately after death. Also the alimentary tracts of seven adult sheep were obtained immediately after death.2. The rumen had the fastest growth rate of the four stomachs, followed by the reticulum, omasum, and abomasum, in that order.3. Immediately after birth the four stomachs altered rapidly in their relative proportions, but by about 66 days of age they had reached approximately adult proportions.4. The weights of the liver, heart and kidneys, relative to live weight, decreased during the first few weeks of life, and thereafter remained constant.5. The weight of the spleen, relative to live weight, increased during the first week of life and thereafter remained constant.

Description: Three experiments were carried out to obtain more information upon the effects of varying the plane of feeding for bacon pigs.Exps. 1 and 2 followed the same 3 × 2 factorial design in which (a) diets were fed with or without procaine penicillin and (b) a comparison was made between very high (VH-VH), high (H-H) and low (L-L) planes of feeding for pigs from about 8 weeks old to slaughter at about 200 lb. live weight. The planes of feeding were defined according to the amount of t.d.n. offered to each pig daily.For each of these two experiments eight lots of six litter mates were used. One pig from each litter was allocated to each of the six treatments, and although litter mates were housed as a group, all pigs were fed individually in separate compartments.Exp. 3 was a 2 × 3 × 2 factorial to compare two breeds and three planes of feeding during 2 years. During each year three lots of pure-bred Landrace and three lots of Wessex Saddleback × Large White litter mates were used. Each lot consisted of three gilts and three barrows and one pig of each sex was allocated to each of the three feeding treatments. From the start of the experiment, when the pigs were about 8 weeks old, to about 100 lb. weight, all animals were kept to a very high (VH) plane of feeding. From then to slaughter at about 200 lb. live weight the following planes of feeding were compared: (1) very high plane (VH), (2) increasingly restricted plane (R) and (3) low plane (L). As in Exps. 1 and 2 these planes were denned in terms of t.d.n., and litter mates were housed together but fed individually in separate compartments.In both Exps. 1 and 2 pigs with procaine penicillin in their feed grew very slightly faster and more efficiently than those not fed antibiotic, but the differences did not reach the 5% level of statistical significance. The feeding of antibiotio did not affect the response of the pigs to variations in the plane of feeding.In comparison with pigs kept to the VH-VH plane of feeding, pigs kept to the H-H and L-L planes grew 13 and 22% more slowly in Exp. 1, and 11 and 26% more slowly in Exp. 2, but plane of feeding had no effect upon food conversion efficiency in either experiment. These results are for the total experimental period.In both Exps. 1 and 2 reductions in plane of feeding had no significant effect upon length of carcass or thickness of streak, but they caused increases in killing-out percentage and decreases in all measurements of fat thickness. They also caused increases in the area of ‘eye’ muscle (statistically significant in Exp. 2, but not in Exp. 1) and a lengthening in the shape of the ‘eye’ muscle in the bacon rasher (statistically significant in Exp. 1, but not in Exp. 2).In Exp. 3 the Wessex crosses grew faster and more efficiently than the Landrace, but these differences were considerably larger during one year than during the other. In comparison to the Landrace, the Wessex-cross carcasses had a tendency to be shorter (P 〈 0·10) and to have thicker shoulder fats. They also had 1% more ‘fore’ and 1% less ‘ham’.Compared with pigs kept to the VH-VH plane of feeding, those kept to the VH-R and VH-L planes grew 18 and 36% more slowly, respectively, during the finishing period. Over the total experimental period there was no difference in food conversion efficiency between pigs kept to the VH-VH and VH-R planes, but efficiency was poorer by 4–5% with the VH-L plane. There was no breed × feeding interaction in the data for growth rates or food conversion efficiencies.In Exp. 3 plane of feeding had no significant effect upon killing-out percentage, shape index of ‘eye’ muscle or thickness of streak. The two lower planes of feeding caused reductions in the average rump fat, fat (1) over the ‘eye’ muscle and in the proportion of ‘middle’ in the carcasses; they also caused increases in the proportion of ‘ham’ in the carcasses.Other carcass quality data contained significant interactions which complicated their interpretation. The effects of plane of feeding were inconsistent between:(A) years, for length of carcass, maximum shoulder fat, area of eye muscle and iodine values of the back fat;(B) breeds, for minimum back fat and percentage ‘fore’;(C) sexes, for dressing percentage and fat (2) over ‘eye’ muscle;(D) breeds and years, for dressing percentage;(E) breeds and sexes, for maximum shoulder fat.The results of the three experiments have been compared with other data on planes of feeding from Rowett Research Institute. A table has been given showing the probable average effects of using different planes of feeding in preference to a VH-VH plane for pigs to be slaughtered at about 200 lb. live weight. The variability in these effects under different circumstances has been discussed and a note has been made of the relative improvements in carcass quality which can be affected through feeding and through breeding.

Description: 1. A survey of the reasons for disposal of 1000 sows from farms in a selected area of East Anglia showed that the most important causes of sow wastage were ‘failure to breed’, ‘piglet mortality’, ‘old age’ and ‘low fertility’ which together accounted for 64·3% of the sows.2. The average length of breeding life was 3·75 litters per sow and the modal number of litters was only two. This expectation of life is very short but is in agreement with an earlier estimate based on Breed Society records.3. Failure to breed was the most important cause of sow wastage and accounted for 21·4% of the sows. The incidence of reproductive failure was greatest in young sows and of all the sows discarded as sterile 30·3% were discarded after having had only one litter. Cases of failure to breed were divisible into two broad groups.

Description: 1. An analysis of pre-weaning mortality in inbred Large White pigs showed that the over-all mortality in ten generations of sows was 47·3%. During the first four generations mortality fluctuated between 30 and 45%; from the 5th to the 9th it fluctuated between 50 and 68% and in the 10th rose to 88%.2. 70·2% of all deaths occurred in the first 3 days post-parturition and the average birth weight of pigs which died within 3 days was only 1003·5 g. compared with 1258·5 g. for those which survived. 83·0% of pigs weighing less than 900 g. at birth died within 3 days, whereas only 18·5% of pigs weighing more than 1400 g. died within the same period.3. There were marked seasonal variations in mortality, this being highest during the winter months. Mortality was highest in litters of under 5 and over 15, but between 5 and 15 there was no increase in mortality with litter size. There was no difference in mortality between males and females.4. Foetal growth was studied in 80 outbred sows of various breeds. Foetal weight was affected not only by age but also by litter size. The withinlitter variation in foetal weight increased with litter size but no increase in between-litter variation with litter size could be demonstrated statistically. Male foetuses were slightly heavier than females at all stages of pregnancy investigated.5. The growth of the inbred Large White foetus was also studied at an early and late stage of inbreeding, and the reduced birth weight in the latter was shown to be reflected in slower growth of the foetus from mid-pregnancy onwards.6. The anatomical composition of inbred Large White foetuses at a late stage of inbreeding has been compared with that of similar foetuses at an earlier stage and also with normal outbred Essex foetuses, at 51, 74, 97 and 108 days of pregnancy. The chemical composition of inbred Large White foetuses of a later stage of inbreeding was compared with that of outbred Essex foetuses at 51, 74, 97 and 108 days. The differences in anatomical composition between the smallest and largest foetuses within litters are comparable with those found postnatally in pigs fed on a high or low plane of nutrition, but this was not reflected in a very definite way in the chemical composition. X-ray photographs showed that ossification was more advanced in the largest foetus within a litter than in the smallest but the appearance of the ossification centres was not delayed in the latter.7. Attempts to make reciprocal ovum transfers between inbred Large White and outbred Essex sows met with little success, probably due to the low fertility of the Large Whites, the prolonged exposure of the ovum during transference and the necessity of effecting the transfer of the ova at the 2-cell stage. The latter was conditioned by the rate of passage of the ova through the tube and the fact that they enter the uterus in the 4-cell stage.

Description: Early morning and midday body temperatures of rams and ewes of three breeds of sheep were measured once weekly for a period of 10 months in Northern Rhodesia and 12 months in Southern Rhodesia.1. In all breeds seasonal fluctuations in body temperature were due to concurrent fluctuations in ambient air temperature.2. Mean annual body temperatures were: Merino 102·2° F.; Persian 101·7° F. and Native 101·7° F. Wool and hair breeds differed considerably in their early morning temperatures and in their body temperature increases from 6.30 a.m. to 12.30 p.m. Mean annual values for these measurements were Merino 101·73 and 1·92° F.; Persian 100·81 and 1·83° F.; Native 100·73 and 1–92° F. At all times Merinos showed markedly greater uniformity of body temperature than either hair breed. There was no evidence to show that the thermoregulatory mechanisms of these animals had been stressed unduly.3. Sex had no consistent effect on body temperature or on rise in body temperature.In general, lactating ewes showed a significantly higher initial body temperature than either empty or pregnant ewes, but the respective heat tolerances as measured by body temperature increase did not differ appreciably. Body temperature differed little in empty and pregnant ewes.4. Although the youngest group of ewes in each breed showed the highest early morning temperature, there was no evidence that heat tolerance was less in young than in old animals.5. Black-coated Native ewes had higher initial body temperatures and a smaller body temperature increase during the summer months in Southern Rhodesia than brown or broken-coloured Native ewes. These effects were due to differences in coat density rather than to differences in coat colour or skin pigmentation.6. In all breeds the magnitude of the diurnal and annual variation in body temperature was different in Northern and Southern Rhodesia. Differences were largely of climatic origin but low plane of nutrition in Southern Rhodesia possibly reduced critical body temperature and impaired thermoregulatory ability.

Description: 1. The change in concentration of 131I with time in plasma, urine, milk and the thyroid gland has been followed in four cows after administration of either a single oral dose or of 131I from a decaying source every 6 hr. for 14 days.2. The observed changes in concentration following multiple doses have been compared with those predicted from the single-dose experiments.3. Small discrepancies were observed between the observed and predicted course of events in urine, milk and the thyroid gland: their significance is considered to be doubtful.

Description: 1. A mixed sward was divided into two areas receiving high (H) or low (L) levels of fertilizer nitrogen, and on two occasions, in spring and summer, herbage cut from each area was given to three steers in a continuous digestibility trial lasting 45 days. Digestibility and faecal nitrogen concentration were measured for each animal for each 24 hr. period, and equations relating these variables were calculated for each trial from the unit 24 hr. observations and from averages over three animals and over successive 2-, 3-, 5- and 9-day periods.2. In the two spring trials herbage digestibility remained constant for the first 12 days and then declined by about 0·4 units per day. In the summer trials digestibility declined throughout by 0—25 units per day. The nitrogen content of the herbage was consistently 25% higher for treatment H, and declined steadily throughout each trial.3. Both season of cutting and fertilizer treatment had a significant effect on the faecal index regressions obtained. Equations calculated from average values for three animals and 3 days predicted digestibility coefficients from 3% faecal nitrogen as follows: equation (1) spring H, 76·5; (2) spring L, 77·5; (3)summer H, 71·8; (4) summer L, 72·8.4. The joint residual standard deviation for equations (1) to (4) had the low value of ± 0·90 units of digestibility, indicating that ‘single-sward’ regressions are considerably more accurate than those embracing a great variety of herbages. Even greater accuracy was obtained when digestibility and faecal nitrogen concentrations were measured for periods longer than 3 days; in general, residual variance varied inversely with period length. Using values for individual animals in the regressions increased the residual variance slightly, but because differences between animals in the digestibility-faecal nitrogen relationship were small and generally nonsignificant, the increase was by a factor of the order of 1·6, not 3.5. Standard errors of prediction were calculated, although there is evidence to suggest that these underestimate the error of digestibility coefficients predicted for free-grazing animals. It is concluded that faecal index regressions are accurate enough for measuring digestibility per se in grazing experiments. In the measurement of herbage consumption, however, the experimental error is likely to be high, partly because indigestibility is the factor required to be predicted, but mainly because of large differences in appetite among similarly treated animals.

Description: 1. A relatively inexpensive closed-circuit respiration chamber for cattle is described.2. Experiments with two steers are reported in which heat production and energy retention data were measured at different levels of food intake and at different environmental temperatures.3. The energy lost in faeces increased with improving plane of nutrition but was not significantly affected by the environmental temperature. Urine energy losses fell with increasing environmental temperature at low planes of nutrition. Methane losses increased with improving nutritional plane but were reduced by high environmental temperatures at high levels of food intake.4. The heat production of fasting animals, or animals on low planes of nutrition was not influenced by the environmental temperature in the range 20–40° C. On higher planes of nutrition an increasing environmental temperature increased the animals' heat production.5. The major factor determining energy retention in different environments is the heat production of the animal. Net energy values consequently vary with temperature.

Description: The influence of fleece on thermoregulation in German Merino ewes was investigated in Rhodesia. Comparative heat tolerances of Persian Blackhead, indigenous Native and shorn and unshorn Merino ewes were obtained during the hottest month of the year in Northern Rhodesia. The main thermolytic responses in unshorn, partially shorn and completely shorn Merino ewes were measured at 7.0 a.m.; 10.0 a.m.; 1.0 p.m. and 4.0 p.m. during April in Southern Rhodesia.1. Unshorn Merino ewes showed more and shorn Merino ewes less effective body temperature regulation than Persian or Native ewes. High heat tolerance in unshorn Merinos was due primarily to insulation by the fleece and not to more efficient physiological thermolysis than in hair breeds. No ewe showed signs of undue thermal stress and feed intake was not affected by heat.2. Increases in rectal temperature and respiratory rate between 7.0 a.m. and 1.0 p.m. of Merinos in Southern Rhodesia were related inversely to fleece length. Body temperature did not differ significantly at 1.0 p.m. owing to differential rates of increase in respiratory rate.3. Magnitude of the diurnal fluctuation in skin temperature was also related inversely to fleece length. Partially shorn ewes, however, began with and maintained highest skin temperature through the heat of the day. In all groups skin temperature fell after 10.0 a.m. although ambient temperature continued to rise. This fall could not be attributed to sweating since moisture secretion declined simultaneously.

Description: Sixteen osteodystrophic dwarf cattle and ten controls of comparable age were slaughtered. The components of the body and eviscerated carcass were weighed and measured. At birth the dwarfs were thick and blocky. At the time of slaughter a bulging forehead was common but not always extreme and not always present. The symptoms of dwarfism became increasingly pronounced with age, due to retarded growth. The dwarfs had shorter thoracic cavity, abdominal cavity, body, loin, hind leg, arm bone and forearm bone than the controls. No explanation can be given for the difference. However, the dwarfs were hydrocephalic and had significantly lighter adrenal and pituitary glands than the control animals. The dwarf animals had more blood, heavier feet, less abdominal fat, smaller loin ‘eye muscle’ area at the 12th rib and a less deep loin ‘eye muscle’. The dwarf females had a lighter rumen (with and without contents) and large intestines (without content) as a percentage of live weight than the controls and dwarf males. There was no difference in palatability of the meat or percentage of wholesale cuts from the dwarf and control animals except for percentage of plate. The following three ratios were disproportionate in the dwarfs as compared with the controls:

Description: A simple method has been described for measuring photosynthesis of detached leaves.The reduced rate of photosynthesis of the tea leaf, immediately after excision, is due to stomatal closure. In mature detached leaves, kept well supplied with water in diffuse light or darkness and in a humid atmosphere, normal stomatal opening and maximum photosynthetic rates were obtained between 12 and 30 hr. from excision. Stomata on sunflower leaves do not close on excision.Variation in the initial concentration of CO2 between 1·0 and 4·0% vol. with a final concentration not below 0·5% did not affect the rate of photosynthesis of sunflower leaves at 25° C. and under 32 klux light intensity. Under the same conditions of light and temperature, there was no change in the photosynthetic rates of tea leaves in 1 and 2% initial and 0·2% final CO2 concentrations. There were indications that CO2 concentrations below 1·0% might be rate-limiting for certain tea leaves, assimilating under low light (4 klux).The development of photosynthetic capacity in the young leaves of tea and sunflower is a gradual process. In sunflower, the photosynthetic capacity develops fully before, and in tea after the leaf reaches half its final size.

Description: 1. The general seasonal trends of top-soil nitrate and ammonia-N, and growth of the coffee tree are described for conditions of both soil and climate which are representative of a large proportion of the coffee-producing area in Kenya.2. When rainfall is heavy and persistent at the beginning of a rains period soil nitrate-N levels decrease rapidly, partly because of leaching losses and partly through uptake by the crop. Under conditions of rainfall and cropping similar to those described for the first half of 1954, the flush of nitrate-N in the early part of the rains will not be detected under field conditions. When the onset of the rainfall season is more gentle and substantial water movement through the upper part of the soil profile does not take place, for example, Short Rains, 1954, nitrate-N values do not decrease rapidly and there is indirect evidence of the stimulatory effect of this type of rainfall on nitrate-N formation in a remoistened field soil.3. Rapid and substantial build-up of nitrate-N is shown to take place during intervening dry weather between the rainfall periods. This is particularly marked in the top 6 in. of the soil profile and is attributed to nitrate-N formation in the absence of leaching losses; to a decreased rate of uptake by the coffee tree in the absence of vigorous growth and to the physical movement of nitrate-N upwards into the top-soil.It may be inferred from the results that alternate periods of rain and sunshine, rather than continuous heavy rain, will favour high soil nitrate-N levels and a more satisfactory nitrogen nutrition of the coffee tree.4. During periods of very low soil moisture ammonia-N builds up in the dry top-soil.5. The sharp peak and rapid decline in the rate of coffee growth during the Long Rains period coincides with very low soil nitrate-N values although climatologically conditions for continued growth are still excellent. This suggests that low available soil nitrate -N may be at least partially responsible for this early and rapid decline in the growth rate.6. In the light of observed trends in nitrate-N and coffee growth the timing of fertilizer nitrogen application to mature coffee has been altered. During the Long Rains split applications are recommended with the particular object of maintaining a supply of readily available nitrate-N in the soil. An additional and supplementary fertilizer nitrogen application is also suggested in the Short Rains period.

Description: It is shown that reasonable estimates of the average amounts of total digestible nutrients and gross digestible energy of ruminant feeds can be derived from knowledge of only the crude-protein and crude-fibre contents of such material as fed. These estimates do not appear to be markedly affected, if at all, by differences in class of feed or species of ruminant whether cattle, sheep or goat.A table of the average estimates of digestible crude protein and total digestible nutrients, to be expected at different levels of crude protein and crude fibre, is presented for use in the estimation of the average nutritive value of feeds whose digestibility has not been studied in detail by means of numerous animal trials.Inherent in the relationship between either total digestible nutrients or gross digestible energy and the proximate partial composition of the feed is a suggestion that if a low plane of protein nutrition is prolonged, that is when the crude protein of the dry diet lies persistently below some 5% in the dry feed, there is likely to be a sharp fall in the total digestibility of the feed.

Description: For 8 weeks after farrowing, sows were fed their standard ration (depending on the number of piglets being suckled) in either thirteen or fourteen feeds per week. The omission of one feed per week did not affect the performance of the 3-week-old litters whether reared indoors or outdoors. The response of the 8-week-old litters to sow-feeding system, however, appeared, from the limited data available, to be inconsistent over rearing environments, those reared outdoors being more affected by feeding system than those reared indoors. The outdoor reared litters consumed significantly more creep feed and were significantly heavier at 8 weeks of age than litters reared indoors, confirming previous observations. During the suckling period the sows lost on average 74·4 lb. in weight; weight loss was not influenced by environment or feeding system.

Description: Mature and young Merino, Persian and Native rams were compelled to run 1 mile in 10–12 min. The response to the thermal burden induced by this exercise was measured in terms of body and skin temperatures, rate of respiration and length and temperature of the scrotum.1. Marked increases were recorded in every body response immediately after the exercise. Body, skin and scrotal temperatures returned to normal within 2 hr. but respiratory rate remained elevated for a further 4 hr.2. There were breed differences in the initial and subsequent measurement of every response. At 7.0 a.m. when there was no thermal stress body temperatures and rates of respiration were: Merino 102·9° F.; 3·-6 cyc./min. Persian 101·4° F.; 23·8 cyc./min. Native 102·1° F.; 28·9 cyc./min. Merino rams had the greatest ability to combat rising ambient temperature, Native rams the least. Persian rams recuperated quickest after exercise, Native rams slowest. The different responses of wool and hair breeds were apparently due to their coats. Merino fleece stabilized body temperature, did not aggravate the effects of exercise unduly and did not greatly hamper elimination of heat from the body after exercise.3. In all breeds respiratory evaporation was the principal thermolytic process. Rate of respiration was a sensitive indicator of thermal stress but it could not be used as an index of heat tolerance because the associated changes in respiratory volume were not known.4. Age was seldom of significant importance to determine response to thermal burden. In general young rams were affected less adversely by exercise and more adversely by rising ambient temperature than were mature rams. These differential effects were probably due to leggy conformation, low live weight and physical fitness in young rams on one hand, and incomplete development of the thermoregulatory system on the other.5. Increase in scrotal pendulance was related inversely to ability to maintain normal body temperature.6. In view of the influence of age and body conformation on the response to exercise it was questioned whether comparable heat tolerance indices could be obtained by this method.

Description: Responses in body, skin and coat temperatures, cardio-respiratory frequencies and rate of moisture secretion of ewes of three breeds to the diurnal fluctuation in ambient temperature were recorded in the presence and absence of drinking water during the hottest part of the Rhodesian year.1. At 7.0 a.m. body temperatures were: Merino 102·8° F.; Persian 102·2° F. and Native 101·5° F. Between 7·0 a.m. and 1·0 p.m. body temperature rose almost equally in Persians and Natives and fell slightly in Merinos. Change in body temperature between 7.0 a.m. and 1.0 p.m. was not affected significantly by availability of water nor age of ewe, but varied with type of thermal burden (i.e. solar insolation only v. solar insolation plus artificial heat) when water was not available. Although air temperature fell towards late afternoon body temperature of Merinos and Natives rose appreciably, that of Persians only slightly.2. At 7·0 a.m. respiratory rates were (cyc./min.): Merino 59·6; Persian 43·0; Native 29·9. Increase in rate of respiration was the main thermolytic mechanism in all breeds. Merinos had a lower threshold of respiratory response to rising ambient temperature than either hair breed but increase in rate of respiration between 7.0 a.m. and 1.0 p.m. did not differ significantly with breed or age.3. No breed appeared to use the peripheral blood system in thermoregulation. Cardio-frequency, as a measure of this blood flow, remained almost constant with a slight tendency to fall with rise in ambient temperature.4. In all breeds skin temperature was related to ambient and body temperatures; consequently the diurnal fluctuation in skin temperature differed in wool and hair breeds. When thermal burden was greatest Merino skin temperature fell, that of hair breeds did not.Except at 11.0 a.m. there was a gradient between rectal, skin and air temperatures. Direct elimination of heat was thus possible for 23 hr. each day.5. In hair breeds moisture secretion depended on insensible perspiration; consequently, rate of moisture secretion changed with body and air temperatures. In Merinos moisture for skin surface evaporation was provided by sensible and insensible perspiration. Natives may be able to sweat at temperatures higher than those recorded but it is unlikely Persians have a sweating mechanism.6. In all breeds coat temperature was related closely to ambient temperature and changes in solar conditions evoked immediate response in coat temperature. Merino fleece apparently stabilized skin temperature whereas Persian and Native hair did not.

Description: 1. Fifty-two experiments were made with two Cheviot and two Blackface wether sheep in which heat production and heat emission were determined at environmental temperatures of 8, 20 and 32° C. Initially the sheep were closely clipped to within 1–2 mm. of the skin and the fleece was then allowed to grow throughout the experiments.2. At 32° C. fleece length had no effect on heat production. At 20° C. metabolism was elevated until fleece length exceeded 18 mm. At 8° C. metabolism was elevated until the fleece length exceeded 35–40 mm. No differences were found between the two breeds in their heat production at a particular temperature provided fleece length was identical.3. The sensible loss of heat divided by the temperature gradient from the rectum to the environment (conductance) was linearly related to the logarithm of fleece length, both at environmental temperatures above and below the critical temperature.4. No differences between the two breeds or between them and Down Cross sheep were found with respect to their conductances when devoid of fleece. The insulation provided by unit length of fleece was the same in all three breeds and crosses. The fleece of the Blackfaces grew at twice the rate of that of the Cheviots so that at a given time after shearing, the Blackfaces were more resistant to concold.5. Studies of the losses of heat by the vaporization of water and of skin and fleece surface temperatures also showed no differences between breeds.6. Analysis of the relation between heat concold, ductance and fleece length suggests that vasoconstriction and vasodilation border on all-or-none effects.

Description: A study has been made of all eggs laid over a year (March-March) by twelve birds.It was found that:1. Shell thickness, yolk weight and white weight all increased with time.2. For each individual bird a linear relationship existed between yolk weight and yolk calcium weight and between yolk weight and yolk phosphorus weight.3. High calcium diets significantly increased shell thickness at the beginning of the experiment and yolk calcium around the middle of the experiment. Dietary calcium levels had no other effects and dietary phosphorus levels no effects at all.4. The ‘curves’ relating shell thickness and time for each individual bird are discussed in relation to the relative merits of different birds as producers of thick shells.

Description: 1. In seventeen digestibility trials carried out between May and November, 1957, groups of three steers were fed on fresh herbage, cut mainly from mixed swards. Herbage digestibility and the concentrations in faeces of the index substances nitrogen and chromogen were measured over periods of 5 days. Organic matter digestibility ranged from 61·2 to 78·9%.2. The relationship between herbage digestibility and faecal nitrogen concentration could not be described satisfactorily by a single regression equation for all trials, and separate equations were calculated for (a) first-growth herbage and (b) aftermath (second and third growths). For a given faecal nitrogen concentration herbage digestibility was about five units higher for first-growth than for aftermath herbage.3. For the faecalchromogen-digestibilityrelationship the difference between growths was even greater and, again, two equations were required. In most trials the quantity of chromogen excreted was apparently greater than the quantity consumed.4. The ‘seasonal’ differences in faecal index relationships were caused by the fact that later growths of herbage contained considerably greater concentrations of nitrogen and chromogen than did firstgrowth herbage of the same digestibility. There was also some evidence that the relationships may be affected by the application of nitrogenous fertilizers to the sward.5. In order to avoid biases in the indirect estimation of herbage digestibility it appears important to use different regressions for different growths. Although such regressions would be restricted in their application they are likely to be more precise than general equations. In these trials both nitrogen and chromogen regressions had low residual standard deviations of ± 1·5 units of digestibility.

Description: 1. The effects of the stage of growth and frequency of cutting on the yield and chemical composition of Panicum maximum Jacq., under the tropical humid conditions prevailing in Ibadan area were studied in the season 1953 to 1954. The cutting frequencies adopted were seventeen, eight, six and four times harvesting a year which corresponded respectively to a growing period of 3, 6, 8 and 12 weeks before the plants were cut.2. It was shown that Guinea grass gave the highest growth rate and cumulative green fodder yield (approximately 28 tons per acre) per year when allowed a 12-weekly growth cycle. Cutting the grass every 3 weeks gave a total minimum yield of 20 tons per acre. 6-weekly samplings resulted in higher green fodder yield than cutting it every 8 weeks. Such yield differences which exist among the various cutting treatments, however, are not statistically significant. When yields of edible (leafy) green fodder were considered, the order of superiority was 3-weekly 〉 6-weekly 〉 12-weekly 〉 8-weekly.It was shown that the increased yield of green and dry fodder obtained from the 12-weekly cut grass was made up of both fresh regrowth as well as of grasses which had been growing for 12 weeks.3. P. maximum contains a fairly high percentage of dry matter and this increased directly with the length of cutting intervals. Dry-matter yields, like those of green fodder, were highest for the 12-weekly harvested material, followed in order by the 6-weekly cut, the 8-weekly cut and the 3-weekly cut samples. However, the production of leaves and the accumulation of dry matter in them, are inversely related to the length of growing interval up to and including grasses allowed 8-weekly growing periods.4. The stems of P. maximum tend to mature more rapidly than the leaves, particularly at a growing stage of between 3 and 6 weeks of age. At between the 8 and 12 week growth stages, the development of the stem of P. maximum in relation to that of its leaves was not as rapid as observed in the case of either P. purpureum or of Andropogon tectorum.5. The percentage dry matter, nitrogen-free extract, ether extract and calcium are directly related, while those of crude protein, silica-free ash, phosphorus and magnesium, are inversely related to the length of cutting intervals. It was also shown that the mean percentage crude protein of Guinea grass of about 12 at 3 weeks of growth, declined by 45% to 6·4 when the grass was cut every 12 weeks. The grass contains a high amount of magnesium, a reasonably high amount of calcium, but a somewhat low content of phosphorus, a fact which accounts for the wide calcium to phosphorus ratio. This ratio widened with the length of cutting intervals.6. When Panicum maximum was cut at 3 -weekly intervals, it produced 69·3% more protein, 58·5% more silica-free ash, 32·3% more calcium, 49·6% more phosphoric acid, 71% more magnesium and higher amounts of carbohydrate and total nutrient material than when it was allowed to grow for 8 weeks. Similarly when the grass was allowed a 12-weekly growth cycle, it produced 35% more of total nutrient, 36·5% more of carbohydrate material and 62·2% more of calcium than when it was sampled every 8 weeks. It appears totally unprofitable from the point of view of yield of chemical constituents to subject P. maximum to a growth cycle of 8 weeks.7. Yields of green and dry matter and the percentage crude protein, silica-free ash, and nitrogen-free extract are directly related to the degree of precipitation. In general periods of high rainfall were accompanied by higher yields and percentage content of these constituents, while periods of low rainfall gave rise to smaller yields. The percentage content of crude fibre, on the other hand, was inversely related to rainfall.

Description: 1. The normal sweat glands of twenty-eight calves, nineteen live adult cattle and eighteen slaughtered cattle from temperate breeds were examined. In every animal the lumen of the sweat glands contained a fluid-like material.2. It appeared on examination and rough measurement that the size of the sweat glands taken from animals after slaughter was smaller than that of the glands taken from live animals even when the same sampling technique was used for both.3. The sweat glands of sixteen calves were examined before and at intervals after the animals had been subjected to a hot environment. The glands were always seen full of a fluid-like material.4. It is concluded that if the calf sweat gland is stimulated by heat stress it must function either (a) by simple diffusion through the sweat gland wall and hence to the skin surface, or (b) by a secretory process not involving degeneration of the glandular epithelium. It is probable that at least part of the contents of the lumen of the sweat glands is derived from the epithelium by a process of active secretion.

Description: 1. The efficiency of food conversion of Brown Leghorn fowls inbred for egg number, or egg size, or egg number and egg size have been compared.2. Comparison between the lines was made for egg numbers, total egg weight and total egg energy. Egg energy was the best measure of production, total egg weight was the next best and egg number the poorest.3. When allowance was made for differences in rates of egg production and egg size, there were no differences in the efficiency of conversion of food to eggs between the lines.4. The standard errors of the means for the analytical data on the twelve replicate mixes of the diet were relatively small, but the range in values was appreciable. The importance of analysing diets in nutrition experiments is stressed, particularly for ‘iso-caloric’ diets.

Description: 1. The estimation of milk yield in a herd of suckled zebu cattle has been described.2. Milk yield was found to be relatively stable when compared with weight at calving and subsequent live-weight change.3. Under constant conditions, there was a negative correlation between milk yield and live-weight change in the cows, compared with a positive correlation when both characters were affected by seasonal changes.4. Variation in milk yield was reflected in the growth rate of the calves, but considerably greater quantities of milk were required to increase growth without the aid of extra grass.5. It was concluded that, under the present conditions, calf growth rate could be increased more efficiently by the improvement of nutrition than by selection for high milk yield in the dams.

Description: 1. The formation of a herd of Northern Frontier Zebus for genetical research has been described.2. Details are given of the system of mating used and the type of management adopted.Thanks are due to Dr J. W. B. King of the Animal Breeding Research Organization, Edinburgh, for his advice, to Mr M. A. Witcomb for taking the photographs, and to the Directors of the East African Veterinary Research Organization and the East African Agriculture and Forestry Research Organisation for their encouragement.

Description: 1. The transfer of 131I to milk has been studied in dairy cows following oral administration of carrierfree material in single doses as sodium iodide or as elementary iodine and in daily doses as sodium iodide.2. The total recovery from milk during the 6 days following administration of a single dose in twentyeight experiments on fifteen animals ranged from 1·3 to 19·4% of the dose with a mean value of 5·5%. The variations in recovery can be attributed largely to differences in the milk yield.3. There was no significant difference in the biological availability of 131I administered as iodide or iodine.4. The change in concentration of 131I in milk with time following daily dosing did not follow the predicted course, a peak value being observed in most animals after 1–3 days, followed by a fall and a subsequent rise to a steady value lower than was expected.5. The presence of a concentrating mechanism in the udder has been demonstrated by administration of sodium thiocyanate. Comparison of the milk total 131I: plasma dialysable 131I ratio at different times of the year indicates that the concentrating ability may be lower in the summer than in the autumn-spring months.

Description: 1. Records collected on the steers reared during the long-term experiment on beef production on the Cambridge University Farm from 1946 to 1955 have been analysed to examine the relation of live weight to various body measurements and the dependence of these relations on breed, treatment and age.2. Among the measurements considered singly, chest girth was most closely related to live weight.3. There were marked differences in the slopes of the regression lines relating log live weight to log chest girth during the two phases of the experiment—from birth to 8 months of age and from 8 months to slaughter.4. The regression coefficients in the first period were affected by the treatment on which the calves were being reared. Those in the second period were affected both by the level of feeding the steers were receiving during that period and by the manner in which they had been reared to 8 months.5. Height at shoulder was the measurement which, as a second variate in the regression equations, led to the greatest increases in the accuracy of prediction of live weight. However, the relation of this measurement to live weight was also affected by the treatment.6. It was considered that these measurements show little promise as estimators of live weight which could be generally applied, since their relations to live weight were affected by the treatment of the animal.

Description: 1. The digestibility of diets supplemented with fat has been investigated.2. For adult fowls and young chicks an increase in the fat content was accompanied by a decreased digestibility of the supplemental fat.3. Supplemental fat depressed the digestibility of the carbohydrates when added to a chicks' diet, but had no such effect on a layers' diet.

Description: The digestibility of the non-protein constituents (almost entirely carbohydrate) of ruminant fodders is shown to be a function of the level of the crudefibre and crude-protein components.The effect of increasing crude fibre in the diet is to depress the digestibility of carbohydrate, irrespective of the level of crude protein associated with it.The effect of crude protein on the digestibility of carbohydrate is only well marked when its concentration in the dry feed lies below some 5%, that is when the feed is below approximate maintenance levels. Increasing the crude-protein content of the diet from some 2 to about 5% leads to increased digestibility of carbohydrate, but thereafter in the range of some 6–30% crude protein the protein effect is very slightly depressing to carbohydrate digestibility and is apparently quite negligible at average crude-fibre concentrations to be expected at any given level of crude protein.The implications of the various aspects of this paper are that the variability in digestibility of the non-nitrogenous component of ruminant feeds depends mainly on the respective levels of crude protein and crude fibre in the diet and to a very much lesser extent, if at all, on the species of ruminant or class of feed, be it silage, roughage or even mixture.

Description: 1. The reliability of the Kjeldahl method for the determination of nitrogen in soils has been investigated using a range of soils containing from 0·03 to 2·7% nitrogen.2. The same result was obtained when soil was analysed by a variety of Kjeldahl procedures which included methods known to recover various forms of nitrogen not determined by Kjeldahl procedures commonly employed for soil analysis. From this and other evidence presented it is concluded that very little, if any, of the nitrogen in the soils examined was in the form of highly refractory nitrogen compounds or of compounds containing N—N or N—O linkages.3. Results by the method of determining nitrogen in soils recommended by the Association of Official Agricultural Chemists were 10–37% lower than those obtained by other methods tested. Satisfactory results were obtained by this method when the period of digestion recommended was increased.4. Ammonium-N fixed by clay minerals is determined by the Kjeldahl method.5. Selenium and mercury are considerably more effective than copper for catalysis of Kjeldahl digestion of soil. Conditions leading to loss of nitrogen using selenium are defined, and difficulties encountered using mercury are discussed.6. The most important factor in Kjeldahl analysis is the temperature of digestion with sulphuric acid, which is controlled largely by the amount of potassium (or sodium) sulphate used for digestion.7. The period of digestion required for Kjeldahl analysis of soil depends on the concentration of potassium sulphate in the digest. When the concentration is low (e.g. 0·3 g./ml. sulphuric acid) it is necessary to digest for several hours; when it is high (e.g. 1·0 g./ml. sulphuric acid) short periods of digestion are adequate. Catalysts greatly affect the rate of digestion when the salt concentration is low, but have little effect when the salt concentration is high.8. Nitrogen is lost during Kjeldahl analysis when the temperature of digestion exceeds about 400° C.9. Determinations of the amounts of sulphuric acid consumed by various mineral and organic soils during Kjeldahl digestion showed that there is little risk of loss of nitrogen under the conditions usually employed for Kjeldahl digestion of soil. Acid consumption values for various soil constituents are given, from which the amounts of sulphuric acid likely to be consumed during Kjeldahl digestion of different types of soil can be calculated.10. Semi-micro Kjeldahl methods of determining soil nitrogen gave the same results as macro-Kjeldahl methods.11. The use of the Hoskins apparatus for the determination of ammonium is described.12. It is concluded that the Kjeldahl method is satisfactory for the determination of nitrogen in soils provided a few simple precautions are observed. The merits and defects of different Kjeldahl procedures are discussed.

Description: An examination of the population density and morphology of the apocrine glands of four ‘races’ including fourteen breeds of African indigenous cattle has been completed.Two types of gland were found, the club-shaped and the sac-like, and it is suggested that the former is the more primitive form.Considerable differences in gland density and volume were found. In the thoracic-humped African Zebu both of these were similar to figures given for B. indicus sui generis.Gland volume was found to be closely correlated to heat toleration, but it is suggested that secretory rate is probably of high importance in view of the fact that despite differences in gland volume, there were only small differences in heat toleration coefficient.It is suggested that the heat toleration coefficient as presently defined may not be a reliable indication of the animals tolerance of prolonged high temperatures.A suggestion is made regarding the mechanism of heat control by sweating in cattle.

Description: 1. Twenty-eight experiments on sugar beet in 1956–8 compared ammonium sulphate, calcium nitrate and urea applied to the seedbed before sowing. The three fertilizers were compared at rates which supplied nil, 0·6 and 1·2 cwt. N/acre. Treatments in which 0·6 cwt. N/acre was held back until the end of June were also included.2. Average responses in sugar yield were low, 0·6 cwt. N/acre provided virtually all the nitrogen required for maximum sugar production. The heavier nitrogen dressing, on the other hand, substantially increased the yield of tops.3. Calcium nitrate and urea were as effective as ammonium sulphate at raising sugar yield. There was no damage to germination with any fertilizer, and when urea containing 4·5% biuret was used for topdressing in 1956, no damage was seen. Calcium nitrate and, to a lesser extent, urea produced more tops than ammonium sulphate.4. Putting all the nitrogen into the seedbed was as effective as a split dressing in raising sugar yield. Leaching of nitrogen in a wet summer is therefore not important to sugar beet. Late nitrogen, on the other hand, never harmed sugar production if some had been given to the seedbed.

Description: A long-term calcium and phosphorus balance experiment with laying hens is described.The cumulative balances of calcium and phosphorus over a whole year were seen to be physiologically impossible.Results from other workers using short term balances could be equally impossible and a similar situation has recently been noted in balance experiments with ruminants.The techniques employed in the experiment were, therefore, investigated in detail.Only systematic errors could be responsible and it was found that the most likely source of such errors was (a) the spilling of food on to the floor or into the water bowl, and (b) failure to collect all the droppings.These errors only become apparent in long-term experiments and are more pronounced when diets containing high levels of calcium and/or phosphorus are fed.

Description: Factors affecting the grazing habits of ruminants are discussed in relation to the attractiveness and nutritive value of herbages and the observed preferences of cattle and sheep at different times.Methods of measuring stock preferences are considered and it is concluded that, while frequent eye estimates of the quantity of each species appear to provide an adequate method, continuous observations and herbage sampling are useful adjuncts to it.The results of five experiments are given. Four were carried out in 3 years' winter grazing and one on spring, summer and autumn grazing over 2 years. In the latter experiment herbage samples were chemically analysed and a relationship with the observed preferences was calculated.In the winter grazing trials the greener grasses tended to be selected first, i.e. timothy, white clover, rough-stalked meadow grass, perennial and Italian rye-grass. Cocksfoot, Phalaris, red fescue and meadow fescue were not generally relished. Meadow foxtail, smooth-stalked meadow grass, tall fescue and sometimes the different varieties of rye-grass and timothy varied in rank from year to year as a result of differential frost damage and fungal attacks.In the summer grazing trials lucerne and white clover were found palatable in all the 1956 trials; in 1957 lucerne remained so, but white clover was less well liked, especially in June and July. The amount of grass growing with the clover seemed to affect attractiveness, mixtures being preferred to either species by itself. Meadow fescue and timothy were always ranked high, perennial rye-grass and cocksfoot usually next. Agrostis and red fescue were lowest. For the grasses, preference rank was positively correlated in 1957 with water-soluble dry matter, water-soluble ash, water-soluble carbohydrate and negatively correlated with lignin content.Results are compared with those of other investigators and they show a marked degree of similarity. Variability in the data for sheep is possibly due to limitations in technique. The results for sheep and for cattle are compared; and it was generally found that cattle were fonder of meadow fescue than sheep, and less fond of cocksfoot.Stock appear to graze those plants which will most readily supply their requirements for salts and energy (carbohydrates). Factors like dung, fungal attack, accessibility, density and toughness may interfere with this relationship.

Description: 1. A comparison has been made of the progenytest figures for father and son in the Friesian breed.2. There was a significant regression of contemporary comparison of son on contemporary comparison of father (0·22) and on r.b.v. of father (16·4 lb. per unit of r.b.v.), though both figures were about one-quarter lower than expected. The observed figures were consistent with a heritability of heifer yield of 0·19. The regression of contemporary comparison of son on the average production of the herds in which his half-sibs were milked was small and not significantly different from zero.3. For fat content, the regression of son's daughter average on father's daughter average was 0·32, in agreement with expectation.4. A less-detailed analysis for the Ayrshire breed on the above points gave essentially similar results.5. The possible extent of selection on the basis of progeny-test results was looked into. For yield, the selection was small, leading to a probable improvement of 1–2 gal. a year. For fat content, the probable increase was 0·01% a year.6. A method is described for evaluating the progeny test of a son in relation to his father's own progeny-test results, which can serve as a method of combining the progeny-test figures from different bulls.

Description: 1. An experiment was carried out over 2 years to study the effect of stocking rate on the efficiency of pasture utilization by dairy cows on irrigated perennial pasture.2. Two matched groups of milking cows grazed throughout the experiment on two unequal areas of pasture at stocking rates of 1·0 and 1·7 cows/acre during the first season and 1·2 and 2·0 cows/acre during the second season (L and H groups, respectively). The same rotational grazing technique was used on both areas.3. In each season the experimental period lasted 249 days. During the first 200 days and 215 days of this period in the first and second seasons, respectively, pasture, grazed or conserved (from the same proportion of both areas), comprised the entire ration.4. The H group produced 57 and 59% more milk per acre than the L group during the first and second seasons, respectively. Milk production per cow in the H group was not significantly depressed. The solids-not-fat content of the milk in both seasons, and the butterfat content in the first season, were significantly depressed at the higher stocking rate.5. The body-weight gain of the cowa in the H group, relative to those in the L group, was depressed by 68% (from 170 to 55 lb./cow) and 88% (from 172 to 20 lb./cow) in the first and second seasons, respectively.6. The yield per acre of utilized pasture, based on the nutrient requirements of the cows, was 39 and 38% higher at the higher stocking rate in the first and second seasons, respectively. The estimated individual intake of these cows in the two seasons was depressed by 14 and 20%, respectively. The estimated yield per acre of utilized pasture ranged from 4092 lb. s.e. at 1·0 cows/acre to 6519 lb. s.e. at 2·0 cows/acre.7. The mean daily herbage intake during the second season, estimated by a herbage clipping technique, was 29·5 and 22·9 lb. dry matter per cow for the L and H treatments, respectively. The cows in the H group ate, at each grazing, all the herbage that had grown since the previous grazing, whereas the estimated intake of the L group was equivalent to only 80% of this regrowth. However, the estimated rate of regrowth of the swards on the two treatments was the same.8. Herbage intake estimates derived from a faecal-indicator technique, and observations of the grazing behaviour of the cows provided more detailed information on the pattern of herbage availability on successive days during the grazing of paddocks at each stocking rate.9. The results of this experiment are discussed in relation to the design of grazing experiments and to farming practice.

Description: Dilution of fowl semen with phosphate or saline diluents depressed respiration, while dilution with seminal plasma did not affect respiration. Dilution with Tyrode solution resembled dilution with seminal plasma with respect to respiration. The effect of Tyrode solution seemed to be mainly due to its NaHCO3 content.The effect of Ca, Mg and K ions depended on the anions in the diluents. Phosphate depressed respiration and glycolysis when it replaced saline in the Tyrode diluent.Dilution did not consistently increase respiration and in most cases depressed respiration.Fowl sperm preferentially utilized glucose when glucose and fructose were initially present in equal concentration in the diluent. The sperm metabolize glucose at a faster rate than fructose. No evidence was found for the formation of glucose from fructose under our experimental conditions.Initial respiration and glycolysis of fowl semen was depressed by the addition of glycine to the Tyrode diluent. However, the glycine addition resulted in a less sharp decrease in the hourly respiration rate.

Description: 1. Sixty-two commercial sows with a history of sterility were served either less than 7 days or between 12 and 21 days before slaughter and the ovaries examined at autopsy. Thirty-eight sows had apparently normal ovaries and twenty-four abnormal ovaries. Of the sows with normal ovaries, seven out of ten served within 7 days of slaughter were pregnant, but only four out of twenty-two served between 12 and 21 days were pregnant. Two sows were not served because they did not come into oestrus. Of the sows with abnormal ovaries only one out of nineteen which had been served was pregnant. Thus in sows with apparently normal ovaries it is suggested that the main cause of sterility is embryonic mortality, whereas in sows with abnormal ovaries the main cause is lack of fertilization.2. Sterility associated with cystic ovaries was studied in inbred sows and the oestrous cycle in such sows was found to be irregular, usually with an abnormally long dioestrous interval. There were no cases of nymphomania associated with cystic ovaries.3. The ovaries of ten sterile sows were examined by successive observational laparotomies. In some cases cysts were present together with apparently normal ovulations and it is suggested that the cysts developed from follicles which failed to rupture. In other cases cyclical growth and regression of cysts occurs without ovulations, whereas in others where the cysts are very large (30-50 cm. in diameter) the cysts may be permanent structures. Sows with large multiple cysts frequently show no signs of oestrus and it seems likely that the breakdown in the ovulation process starts with irregular ovulations and tends to proceed towards the development of these large multiple cysts.4. Intravenous injections of Prolan (l.h.) had no effect on the ovarian cysts. Implantation of stilboestrol tablets reduced the cystic condition but the treated sows did not come into oestrus although corpora lutea were found in the ovaries at autopsy. Intramuscular injections of stilboestrol also reduced the cystic condition and in one case a sow actually became pregnant.5. No response was obtained to p.m.s. injections in sows in which the ovaries had reverted to an infantile condition.6. Cystic ovaries were produced by subcutaneous injections of progesterone and these closely resembled those found in sterile sows. The ovaries of gilts with progesterone-induced cysts tended to revert to normal after the cessation of the injections but the fertility of the gilts was low due to failure of fertilization.7. Preliminary attempts to graft ovaries met with little success probably due to immunological reaction against and imperfect vascularization of the grafts. Further attempts were postponed pending the results of trials with sheep using a different grafting technique.8. Evidence as to the effect of fatness in causing sterility in gilts was obtained from the records of the National Pig Breeders' Association. Two overfat experimental gilts which did not come into oestrus were found to have apparently normal ovaries at autopsy and a third came into oestrus and was mated after a period on a submaintenancediet, but though it ovulated normally the ova were unfertilized.

Description: During the course of the main investigation the following observations were made on some other aspects of reproduction in the sow.An examination of the reproductive tract of sows killed at slaughterhouses in East Anglia showed a high percentage of cystic abnormalities in the ovaries (Perry & Pomeroy, 1956). However, the sample of sows necessarily excluded any gilts, so an examination has been made of the incidence of ovarian abnormalities in post-pubertal gilts at two bacon factories. The ovaries of 273 gilts were examined and divided into (a) ovaries containing corpora lutea, (b) ovaries not containing corpora lutea. These were then further classified as normal or abnormal. The chief criteria of abnormality were the presence of cystic follicles, i.e. of greater than ovulatory size (10 mm. in diameter) or cystic corpora lutea, i.e. large flabby corpora lutea with hollow centres. Gilts with numerous haemorrhagic follicles in the ovaries were also classified as abnormal, but it is quite possible that this condition is a common occurrence in gilts just before puberty. However, rather than underestimate the incidence of abnormalities these ovaries were classified as abnormal.

Description: Three different stocks of mice were selected for five generations for high body weight at 3, 4½, or 6 weeks of age. Changes in body weight at the three ages and in abdominal fat weight, an index of carcass composition, which occurred in the three lines were compared. It was found that the proportion of fat in the carcasses of the selected animals increased markedly in the lines selected for high 3-week weight, while in the other two lines the proportion remained the same as that in the control line.The theoretical treatment of the genetic relationship between body weights at different ages and between body weight and abdominal fat was reasonably adequate in accounting for the correlated responses actually observed.

Description: 1. Field experiments are described in which the absorption of radioactive strontium by rye-grass and lucerne has been investigated during 1958 on five soil types which represent a range in exchangeable soil calcium content. 89Sr was applied as a spray to both arable land and to established pasture.2. Absorption was reduced by a factor of up to 4 in rye-grass (shallow rooted) following ploughing to 11 in. compared with leaving the contamination on the soil surface. These results are compared with those obtained in an earlier series of experiments in 1957.3. The ratio of 89Sr to calcium was highest in crops grown on soil low in calcium (2 m-equiv. Ca per 100 g. extracted with N-ammonium acetate).4. The addition of lime reduced absorption of 89Sr from the soil only when the exchangeable soil calcium content was relatively low. Some effect was observed in soils containing 7–8 m-equiv. Ca/100 g., a considerably larger one in a soil containing 2 m-equiv.5. Only small differences occurred in the ratio of 89Sr to calcium between lucerne and rye-grass. This comparison was not made beyond the first 6 months of growth.6. Experiments carried out with established pastures on four soil types indicate that 89Sr is more readily absorbed from the ‘plant-base’ than after incorporation with soil. Ploughing and reseeding may reduce the ratio of 89Sr to calcium in herbage by a factor of up to 4. This effect may be greater on mature swards.7. The liming of contaminated swards reduces the ratio of 89Sr to calcium in herbage by a factor of 2 to 3 regardless of the calcium content of the soil, and liming followed by ploughing and reseeding by a factor of 3 to 7.

Description: Groups of Rhode Island Red chicks were fed a mash made up from East African feedingstuffs or that diet supplemented with a high level rate of aureomycin—97 g. aureomycin hydrochloride per ton of feedingstuff. The chicks were kept on wire for 8 weeks. The initial improved growth rate of the chicks fed the aureomycin supplemented feedingstuff was not maintained, nor was there any statistical indication that the addition of aureomycin improved the feed conversion rate.Although the mortality rate appeared to be very much lower in the chicks fed the aureomycin supplement, the evidence was too limited to allow this to be attributed solely to the effects of the aureomycin.The experiment illustrates the need for careful design in order that the effect of the factors to be tested may be separated from the effects of other factors contained in the experiment and not confounded with them. Moreover, advanced statistical analysis should be used as an invaluable aid to, but not a substitute for, visual or graphical examination of results, for such examination often yields valuable indications of possible lines of analysis and may avoid the drawing of unjustified conclusions.

Description: 1. Ammoniated sugar-beet pulp has been compared with decorticated ground-nut meal, when added to a control diet low in protein, in feeding trials with seventy-five cows on three farms and in a balance experiment with four cows.2. In the feeding trial the cows receiving decorticated ground-nut meal gave 8·4 lb. more milk weekly than cows receiving the control diet. Cows given the diet in which the molassed sugar beet pulp in the control diet was replaced by ammoniated sugar beet pulp gave 7·9 lb. more milk weekly than the control group. The milk-fat percentage was not affected by the treatments. Slight increases in solids-not-fat percentage resulted in an increased yield of solids-not-fat with both high-nitrogen treatments. The increases in milk yield approached statistical significance and the increases in solidsnot-fat were significant.3. It was concluded that the feeding trial showed that the nitrogen added to sugar-beet pulp during ammoniation could be utilized by milking cows, but the experiment did not permit an estimate of the efficiency of utilization.4. In the nitrogen balance experiment the utilization of nitrogen was measured as the sum of milk nitrogen and the nitrogen balance. It was concluded that 29·5 g. of nitrogen from 0·8 lb. decorticated ground-nut cake increased the daily utilization of nitrogen by 12·9 g., whereas 55·7 g. nitrogen from 8 lb. ammoniated sugar-beet pulp increased the utilization by only 6·0 g. In this experiment the efficiency of utilization of the nitrogen from groundnut meal was 44% and of the ammonia nitrogen from ammoniated sugar-beet pulp only 11%.5. Ammoniation raised the crude protein content of molassed beet pulp from 10 to 20%. If for the computation of rations the content of digestible crude protein in sugar-beet pulp is taken as 5·0%, that in the ammoniated pulp should be approximately 7·5%.6. If given in sufficient amounts the ammonia nitrogen had as great an effect as the nitrogen of ground-nut meal in correcting the effects of a diet low in protein.

Description: This paper describes an experiment designed to test the goitrogenic effect of white clover (Trifolium repens L) in ewe lambs grown and taken through a complete reproductive cycle. The sheep were setstocked on four pastures made up of perennial ryegrass and short-rotation rye-grass, both alone and together with cyanogenetic white clover. Since these species differ in iodine content when grown on the same soil, there were probably differences in dietary iodine intake of the sheep in the four groups. Half the animals in each group were injected intramuscularly with an iodinated poppy-seed oil to serve as an iodine depot.At slaughter, 19 months from the commencement of the experiment, thyroid weights indicated a goitrogenic action in the non-injected ewes grazing short-rotation rye-grass and white clover and to a lesser extent in the non-injected ewes grazing perennial rye-grass and white clover. There was evidence of a slight goitrogenic action in noninjected ewes grazing perennial rye-grass. The thyroids of non-injected ewes had similar iodine contents, lying within the range of 0·23–0·29% of the dry weight.In injected ewes, the total iodine content of the serum was three to four times higher than with non-injected ewes and the iodine content of the thyroids was three times greater. All injected ewes had thyroids of normal weight.No effects of iodine supplementation on growth, reproduction or wool production were found.Lambs born to the ewes in the fifteenth month of the experiment were slaughtered when 3–5 months old, the age varying with pasture treatment. Thyroid weights indicated a goitrogenic effect from the clover-containing pastures.

Description: 1. Activity of Lumbricus terrestris, Allolobophora caliginosa and A. chlorotica was unaffected by 15 mg. hexoestrol in solution in 500 g. soil.2. Activity and reproduction of A. caliginosa was unaffected by 10 mg. hexoestrol in 500 g. soil, but 100 mg. and over affected activity and stopped reproduction.3. Egg capsules of A. caliginosa and A. chlorotica developed normally in a saturated aqueous solution of hexoestrol.4. No effect on the soil fauna of grass plots due to grazing with implanted bullocks was observed.

Description: An analysis has been made of the reproductive rates and milk yield of Kenana cattle in a closed dairy herd in Sudan.The average age at first calving was 38·4 months and calvings were most frequent between September and December.The average length of productive herd life of cows was 5·42 lactations.The average interval between successive calvings was 395 days, and this was influenced by years and age.The mean generation interval was 6·72 years.The average milk yield in 224 days was 338 gal. with a standard deviation of 152 gal.There was a close relationship between milk yield and lactation length; r = 0·866 ± 0·013.Milk yield increased by age until the fourth lactation when it was about 137% of the first lactation. The rate of increase in yield between first and second lactation was highest and amounted to 22%.Year of record had a pronounced effect on milk yield.Month of calving had a slight effect on milk yield.The repeatability estimates of single records milk yield, calving intervals, lactation periods and dry periods were 0·432 ± 0·046, 0·058 ± 0·059, 0·192 ± 0·058 and 0·069 ± 0·065, respectively.The increase in repeatability estimates between earlier and later successive milk yield records was accompanied by a decrease in the coefficients of variation of these records.The heritability of a single record milk yield was 0·239 ± 0·245.The rate of annual genetic superiority in milk yield of dams of cows and dams of bulls was found to be 0·74% of the herd average.

Description: 1. A co-ordinated trial has been carried out at eighteen centres to study the effects of feeding various quantities of high-protein supplement to growing-fattening pigs. In treatment 1, 10% white fish meal was included from weaning to 150 lb. live weight and 3% soya-bean meal was included from 150 lb. live weight to slaughter (approximately 210 lb.). Treatment 2 was the same as treatment 1 except that only 7% white fish meal was included during the first stage. Treatment 3 was the same as treatment 2 except that the rations were changed at 1001b. live weight instead of 1501b. Treatment 4 was the same as treatment 3 except that highprotein supplement was omitted altogether after 1501b. live weight; thus there were three rations involved in treatment 4—7% white fish meal from weaning to 100 lb. live weight, 3% soya-bean meal from 100 lb. to 150 lb. and no high-protein supplement thereafter.2. Growth rate and feed conversion both differed significantly between treatments. Pigs on treatment 1 grew 5·0% faster than those on treatment 4; the average growth rate for treatments 2 and 3, the difference between which was negligible, was 3·3% higher than for treatment 4. Feed conversion for treatment 1 was 5·4% better than for treatment 4 and the average for treatments 2 and 3 was 3·8% better than for treatment 4.3. Treatment differences were not significant for killing-out percentage, length, quality of fat, proportions of gammon, middle and fore-end of the cured side, thickness of streak, size of eye muscle and amount of fat over it. Some of the fat measurements differed significantly between treatments; differences in fat thickness at the shoulder, middle and rump between treatments 1, 2 and 3 were generally small, but the lowest protein level (treatment 4) resulted in carcasses with about 2% more fat along the back than the average of treatments 1, 2 and 3. These slight differences in back-fat thickness did not result in significant differences in the percentage of pigs in the highest grades.4. An economic appraisal of the results suggested that under the conditions prevailing at the time of the experiment treatment 3 would have resulted in the greatest profit per year, and the greatest profit per pig. This ration was relatively cheap compared with those of treatments 1 and 2 but it did not lead to a seriously impaired performance, as did that of treatment 4, the cheapest ration.

Description: Twenty semen samples were collected by means of the artificial vagina from three Friesian and two Dexter bulls. In each sample, the head length and head breadth of spermatozoa which did not take up the nigrosin-eosin stain, and their percentage before and after 72 hr. of preservation in egg-yolk-citrate and egg-yolk-glycine, were studied. The following results were obtained from the study:1. No significant variation was found in the two measurements of sperm head before and after preservation in E.Y.C.2. Both the head length and head breadth of spermatozoa preserved in E.Y.G. were significantly less than those before and after preservation in E.Y.C..3. The change in size of the spermatozoa head in E.Y.G.. dilutor may be due to an alteration in the acrosome.

Description: Motility characteristics of bull spermatozoa in mixed ejaculates of different bulls were compared with those of the unmixed samples after 40-to 50-fold dilution with clarified standard egg-yolk—citrate buffer (pH 6·80 ± 0·05 at 37° C., 6·75 ± 0·05 at 22–23° C).Using the photo-electric equipment described by Rikmenspoel (1957b) and by Rikmenspoel & Van Herpen (1957) the mean velocity , the number of spermatozoa passing by a constant spot per time unit n, the total number of spermatozoa moving normally N, the velocity decrease with time ( — d/dt), the half-life period of the number of passages per time unit t½(n) and the half-life period of the total number of spermatozoa moving normally t½(N) were determined. For none of these characteristics was any statistical difference found between the actual results and the expected values based on calculation from the data obtained with the unmixed ejaculates.Acid production was investigated by accurate determination of pH change on incubation of samples diluted ten times with standard egg-yolk—citrate buffer containing 736 mg. added fructose per 100 ml. Again there was no statistical difference between the values found with the mixed semen samples and the expected values.It is concluded that differences observed by other authors must be due to the effect of environmental factors, i.e. to the semmal plasma, for which there is analogous evidence in human sperm physiology.

Description: Nitrification of urea and its loss through the volatilization of NH3 were studied under different soil conditions. Under all conditions less urea was nitrified and more time was needed for its nitrification in sandy than in sandy loam soil. Nitrification was favoured at lower concentration of urea, onethird moisture of the moisture-holding capacity and at neutrality or the alkaline pH.Loss of NH3 was found to be twice as much from the sandy loam as from the sandy soil. It was also found that half of the total loss occurred during first drying. Loss of NH3 from urea was found to be proportional to its concentration. The loss increased with the increase in soil moisture and temperature; but it decreased with the decrease in pH on the acid side and the increase in depth of its placement.

Description: 1. Italian ryegrass, laid down for two years, was used to compare the value of casein and formalized casein, ammonium sulphate, calcium nitrate and urea for grassland production. Residual effects of these treatments were measured on a third-year crop of barley.2. Single dressings of ammonium sulphate and casein were of similar value at each of three cuttings in 1956.3. Casein treated with formalin released nitrogen much more slowly and was of little value in the early part of the growing season. Formalized casein produced significantly higher yields than casein at the later cuttings in both years, but aggregate increases from this material were much lower than those obtained from untreated casein in each season. Formalized casein increased yields considerably in the year following application.4. Single dressings of formalized casein were also compared with ‘repeated’ dressings of ammonium sulphate, calcium nitrate and urea, in which the same total quantity of nitrogen was divided equally between cuttings. Formalized casein produced much lower yields than these ‘repeated’ dressings in the early part of the season, but was of only slightly less value at the last cut in 1956 and gave the highest yield at the final cut in 1957. Aggregate yields from repeated dressings of inorganic N fertilizers were higher than those given by single dressings of either form of casein.5. Comparisons were also made between the yields given by ammonium sulphate, calcium nitrate and urea. Urea applied before sowing (at 0·5 cwt. N/acre) damaged germination and reduced plant establishment slightly. Under dry conditions both urea and calcium nitrate tended to give higher yields than ammonium sulphate but with adequate rain all three fertilizers gave similar yields.

Description: Article by van Tienhoven: ‘Metabolism of fowl sperm on different diluents.’Tables 1–17: in column headed ‘Source’ read ‘replication’ for ‘respiration’.In the communication: ‘Studies of the skeleton of the sheep. IV. The effects and interactions of dietary supplements of calcium, phosphorus, cod-liver oil and energy, as starch, on the skeleton of growing blackface wethers’, D. Benzie, A. W. Boyne, A. C. Dalgarno, J. Duckworth, R. Hill & D. M. Walker, J. Agric. Sci. (1960), 54, 202–221, Plates A1, A2 and B1, B2 have been interchanged on Plate 9. The letters A, B and C have been omitted from Plate 10, and should read top, middle and bottom respectively.

Description: A study, using the methods of growth analysis, is reported of the accumulation of dry matter in two Natal Common groundnut crops grown at Kongwa, Tanganyika under conditions of relatively low population (26,000 plants/acre) with phosphate fertilizer (F series), and at a higher population (56,000 plants/acre) without fertilizer (O series). The uptake and distribution of N, P, K, Mg and Ca was followed in the F series.In the F series, the dry weight per plant at maturity was 32·7 g., of which 14·9 g. (45%) was kernels, while in the O series the corresponding figures were 20·6 and 10·4 g. The relative growth rates, net assimilation rates and leaf-area ratios were similar in the two crops, with small but consistent advantages to the F series. Nevertheless, the yields per acre were markedly higher in the O series, where total dry-matter and kernel yield were 2540 and 1290 lb./acre, respectively, against 1910 and 870 lb. in the F series. It is shown that this was the result of consistently higher leaf weights per acre and a higher total leaf-weight duration (4180 lb. weeks/acre) in the O series than in the F series, where total leaf weight duration was 2810 lb. weeks/acre.The formation of the kernels continued to maturity in each case, largely at the expense of current assimilation rather than by net translocation from the vegetative parts.The uptake of N, in the F series, reached a total of 63 lb./acre, of which 45 lb. was in the mature kernels. It went largely into the vegetative parts during the first two-thirds of the crop's life, but in the final stages most of the uptake went into the kernels and there was some evidence of translocation of N from the vegetative parts and the shells. N accumulation did not seem to be affected by rainfall fluctuations within the season. The net assimilation rate did not appear to be directly associated with the activity of the plant in accumulating N, but the leaf-area ratio, and the relative growth rate, were associated with the rate of N uptake per unit of plant dry weight.The total P taken up was no more than 4 lb. (of the element) per acre of which nearly 80% was found in the kernels at maturity. There was considerable evidence of translocation of P into the kernels from the vegetative parts of the plant. P uptake (unlike that of N) was heavily reduced in a mid-season dry period, suggesting that P was largely derived from the upper layers of the soil.The total amount of K found in the crop at maturity was about 26 lb./acre, mostly in the vegetative parts. Rather under a fifth was in the kernels, although they constituted 45% of the total dry weight. The data for Ca and Mg are incomplete, but it may be suggested that the maximum accumulation of Ca was around 10 lb./acre, almost all in the vegetative parts, and that of Mg about 5 lb./acre, of which 2 were in the kernels.The grateful thanks of the authors are due to Dr M. T. Friend, of the East African Agriculture and Forestry Research Organisation, Muguga, Kenya, who determined N and P in the samples of the F series, and to Mr G. T. Chamberlain, of the same Organisation, who carried out the estimations of K, Ca and Mg. They would also wish to express their indebtedness to the members of the former Scientific Department of the Overseas Food Corporation who assisted with the work in laboratory and field, and in particular to Mr B. W. Culy, Manager of the Kongwa Experimental Station, who was responsible for the production of the crops.

Description: 1. Three completed series of laying trials involving the incorporation of calcium lactate in the diet are reported.2. The addition of 1 or 2% calcium lactate to a layers mash results in a significant increase in egg production and/or the efficiency of the ration in terms of numbers of eggs per unit weight of food consumed. This effect has been obtained in birds at the onset of lay and also in birds that have been in lay for some 5 months.3. The incorporation of 0·5% calcium lactate appears to be inadequate.4. There is no evidence to date that the effect is attributable to dietary calcium, but the mechanism of action is unexplained.5. Egg-weight, but not egg-quality, as judged by routine candling, is slightly lowered by feeding calcium lactate.

Description: 1. Two methods were used to estimate the frequencies of nine morphological classes of spermatozoa in 257 ejaculates from one Guernsey, five Friesian and seven Hereford bulls at an insemination centre. In nigrosin-eosin stained preparations and in fixed wet preparations the respective mean frequencies (%) were: malformed heads, 1·08 and 0·98; malformed middle pieces, 0·88 and 0·89; bent tails, 3·92 and 4·56; coiled tails, 0·60 and 0·43; free heads, 3·72 and 2·63; free tails, 1·79 and 1·85; neck beads, 0·87 and 0·93; middle-piece beads, 4·91 and 6·83.2. There were close correlations between the two sets of measurements, but the differences of means were significant for free heads, bent tails, coiled tails, neck beads and middle-piece beads.3. The mean percentage of dead (eosinophil) spermatozoa was 21·0.4. The variations in the frequencies of each morphological class and of dead spermatozoa were divided within and between samples, ejaculates, bulls and breeds. The frequencies of all classes differed significantly between ejaculates within bulls; all but broken necks differed between bulls within breeds, and the Friesian and Hereford bulls differed in the frequencies of malformed heads, free heads, malformed middle pieces, free tails, neck beads and dead spermatozoa. The frequencies of bent tails, coiled tails and dead spermatozoa declined significantly with order of ejaculate.5. The interrelationships of the frequencies of each class were examined. Two new methods used to measure the dead-sperm content of semen were shown to give results significantly correlated with those obtained by the conventional staining method and with motility ratings.6. The interrelationships of measurements of the individual characteristics and conception rate were examined. Within-bull variations in conception rate showed a significant positive correlation (P 〈 0·05) with the frequencies of malformed heads and free heads. The between bull variation in conception rate showed a negative correlation with the frequency of neck beads (P 〈 0·05).

Description: Observations in the shed were made for 3 years on groups of cattle and buffaloes of both sexes for pulse rate, respiration rate, rectal temperature and haemoglobin level during the summer months under low and high humid conditions.The average figures for these physiological reactions were always less for buffaloes than for cattle under both dry and humid conditions.Under high humidity conditions cattle cows showed a significant increase in the pulse rate and decrease in rectal temperature whereas respiration rate remained unchanged. In the buffalo cows these physiological reactions showed less change. In both the haemoglobin level was significantly lower during the rainy season.On exposure to direct sun, the buffalo reacted very badly; the Iberia index was 88 for cattle and 61 for buffalo.Because of the smaller variation in the physiological reactions due to increase in humidity at higher temperature in buffaloes (85–93° F.), this species may be considered a better dairy animal than cattle in humid tropical zones if they are protected from direct sun, which can be easily done by altering the time of grazing from day to night.

Description: 1. The apparent cleanliness of the premises in which chicks are reared has little bearing on the growth rate of chicks within a given environment.2. Bacterial counts of faeces from chicks reared under clean or extremely contaminated conditions showed no difference between the two sets of conditions.3. Delaying feeding until 72 hr. after hatching retarded growth to at least 7 weeks of age. If the age of the chicks was calculated from the time at which the chicks were fed rather than the date of hatch, the weights of the chicks fed 72 hr. after hatching corresponded with those of the chicks fed immediately.4. The contents of the duodenum and mesenteric intestine showed higher bacterial counts when feeding was delayed for 72 hr. than when feed was given shortly after hatching. This effect was no longer evident after the chicks were 1 week old.5. Administration of penicillin in the water did not reduce the difference in growth rates between the chicks given feed immediately and those from which feed was withheld.6. Antibiotics may decrease the thickness of the intestinal wall without stimulating growth.

Description: In this paper the results are described of experiments on bull sperm cells with the photo-electric device for measuring the ‘motility’, as developed by Rikmenspoel, van Herpen & van Dam (1956).It was found that the velocity distribution of sperm samples differs only slightly from a Gaussian one. The form of the distribution curve, which is a bit skew, is rather constant between ejaculates. This means that generally the ‘motility’ of a sperm sample can be characterized by the mean velocity of the sperms, the standard deviation of the velocity distribution and the number of cells moving normally. The mean ratio of velocity and frequency of rotation (the ‘speed’ of the screwing movement of the head of the sperm cell) was found to be a less important motility characteristic for most experiments.The scattering of the above-mentioned properties in various ejaculates were measured, while the sperm samples were all kept in the same conditions. It was found that the mean velocity has a rather constant value.A linear relationship between the mean velocity of the sperms of a sample and the viscosity of the diluent is found. This holds also for the dependence of the ‘speed’ of the head movement and the viscosity.The mean velocity of sperm cells was found to increase approximately in a straight-line relationship with the temperature in the range 33–41° C. There were indications that the mean velocity may reach a maximum in the region of 42–45° C.If sperm samples are stored at 4° C, the mean velocity and the number of cells moving normally is found to decrease exponentially. The decrease of the number of cells moving normally is three to four times faster than that of the mean velocity. Some evidence was obtained that the characteristic time for the decrease of the number of cells moving normally is bull-specific.

Description: The influence of various night- and day-temperature regimes on inflorescence initiation and earing in vernalized and unvernalized Lolium temulentum, L. multiflorum, short-rotation ryegrass, and two varieties of L. perenne, and also in the Athabasca strain of Poa pratensis, is described.Vernalization response curves for the ryegrasses, when grown under controlled conditions, are presented, and are consonant with the operation of a first-order reaction as the rate-limiting step in the vernalization ofLolium perenne. Velocity coefficients for the rate of vernalization in various conditions are deduced, and are shown to be higher in seedlings than in seeds, and higher in short days at 10° C. than at 4° C. The Q 10 for the velocity of vernalization over this range is about 2·7.Low-temperature vernalization in L. perenne can occur when low night temperatures are combined with moderately high day temperatures, and it can take place during abundant vegetative growth. In short days and in continuous light mean temperatures up to 10° C, at least, are fully effective, but in 16 hr. photoperiods even 7° C. was not a fully effective vernalizing temperature. The requirement of perennial ryegrass plants for cold treatment may be replaced by short-day induction if light intensities are low and if the plants are continually divided.

Description: 1. Experiments are described in which retention time of digesta in the reticulo-rumen, fermentation rates of rumen contents, and dry-matter digestibilities were studied simultaneously in four grade European and three zebu steers.2. Fermentation rates and rumen retentions were significantly negatively correlated.3. Correlations between digestibility and the other two factors were not significant at a high level.4. The multiple regressions calculated for retention time and fermentation rate were significant at the 5% level and that for digestibility approached this level.5. While only fermentation rates show significant differences for the two types of cattle, the results suggest that grades and zebus differ also in the rate of passage of digesta through the rumen.6. The loss in weight of substrate per unit of fermentation products was measured in in vitro experiments.7. Using certain assumptions, estimates are made of the extent to which the measured fermentation rates could account for the loss in weight of dry matter during digestion, and are compared with the loss actually found.

Description: 1. Milk yields of grazing ewes with single lambs were estimated using two methods—the traditional lamb-suckling technique, and a technique involving hand-milking following stimulated let-down by intravenous injection of posterior pituitary gland extract (known as the oxytocin technique).2. The oxytocin technique gave significantly higher figures for milk production than did the lamb-suckling technique (P 〈 0·01), and this persisted throughout lactation. Variation between ewes was similar for both techniques.3. The two techniques are discussed in relation to the errors involved, and their accuracy and convenience of application to field conditions.4. Differences in milk yield between Border Leicester x Merino ewes, and Romney Marsh x Merino ewes, estimated by either technique, were not significant. Correlation coefficients between lamb growth rate and milk yield of the ewe, measured by either technique, were high up to 7 weeks of age.5. Where the ewes were under the same nutritional conditions before and after lambing, milk yield was not related to the live weight of the ewe, or birth weight of the lamb.

Description: 1. The serum β-globulin phenotype of 141 bulls located at Cattle Breeding Centres in England and Wales was determined by starch-gel electrophoresis.2. The distribution of the contemporary comparison values of these bulls with respect to β-globulin type was investigated. The great majority of the bulls were βAA, βAD, or βDD with very few βAE and βDE and no βEE types.3. The contemporary comparison values for 130 bulls of the three types βAA, βAD and βDD each fell into a normal distribution. The mean and its standard error and the standard deviation of the mean and its standard error were calculated for each of the three curves. The mean contemporary comparison value for the βAA bulls was + 12·2 ± 5·4 gal., for the βAD bulls + 26·8 ± 5·4 gal., and for the βDD bulls + 38·2 ± 5·5 gal. The βAA and βDD means were significantly different (P 〈 0·01).4. The pooled contemporary comparison values of the βAA, βAD and βDD bulls did not give a normal distribution curve, neither did the contemporary comparison values for a sample of 1028 bulls quoted by the Milk Marketing Board. However, when the contemporary comparison values of the βAA, βAD and βDD groups were superimposed around the same mean, the ensuing distribution was normal.5. It is concluded that the β-globulin locus is concerned in the genetic control of milk yield. The estimated mean genetic value of βD over βA is approximately + 50 gal. This is about one-sixth of the total genetic variation in milk yield in the major milk breeds.6. The distribution of butterfat percentages with respect to β-globulin phenotype in four Ayrshire and one Friesian herds was investigated. No difference between the mean first lactation butterfat percentage of the βAA, βAD, and βDD cows in each herd was found. There was an indication (not significant) that the mean butterfat percentage of the βAE and βDE cows in three of the four Ayrshire herds studied was higher than the mean of the other groups.

Description: Soils collected from paddy fields were kept in a waterlogged condition in glass cylinders with and without drainage. After about 2 months of waterlogging soil samples were collected from each cm. depths of the cylinders, both from the bright and dark sides of the cylinders. The soil samples were analysed for iron, manganese and phosphorus. At the beginning these elements were uniformly distributed throughout the entire soil depth, but as a result of waterlogging a distribution pattern developed. More of these elements concentrated on the surface and illuminated sides of the cylinders. It is assumed that such a phenomenon also occurs in the paddy field. These elements by concentrating on the soil surface limit the feeding zones to the top 3–5 cm. of the soil.