ALBERT

Description: In 1939, Pinous & Waddington reported tetraploid early cleavage stages of the rabbit after colchicine treatment of fertilized eggs in vitro. Chang (1944) inseminated rabbit does with sperm suspended in 1/1000 colchicine in 0·9% NaCl and noted a few abnormal young in the resulting litters. No chromosome counts were made, but Chang considered the possibility that colchicine had entered the egg and caused polyploidy. Using the same technique as Chang, Swedish workers have claimed the production of two adult triploid rabbits and one adult triploid pig (Häggqvist & Bane, 1950a, b, c, 1951; Melander, 1950, 1951). This Swedish work has been criticized (Beatty, 1951; Beatty & Fischberg, 1950; Becker, 1952–3; Hertwig, 1951; Nachtsheim, 1950; Rostand, 1951; Venge, 1953). Nevertheless, the technique is ingenious and the claim of great interest. The present note records preliminary attempts to extend the technique to cattle and to confirm the results in rabbits.

Description: Fourteen pairs of monozygous twin cows of mixed ages were used to determine the effect of underfeeding from the 3rd to the 8th week inclusive after calving on milk and butterfat production and on the composition of the milk.Those cows which were well fed over the 6-week period produced more milk and a larger weight of butterfat than their sisters which had been poorly fed. The milk from the well-fed cows had a lower percentage of butterfat, but higher percentages of solids-not-fat and total protein, than the milk from the poorly fed cows.The complete lactation averages failed to show statistical significant differences in all characteristics except in the case of solids-not-fat percentage. The mean difference between the two groups for solidsnot-fat was found to be highly significant.In general, the results support the conclusions of other workers, that underfeeding dairy cows may depress the solids-not-fat content of the milk.It appeared that differences between the two groups in butterfat percentage over the 6-week experimental feeding period were strongly correlated with differences in weight changes and that the small amount of variance associated with milk yield differences was not significant.

Description: It is suggested that part of the increased permeability of soil recently ploughed out from grass could be due to water conduction through the severed roots. Microtome sectioning of a root of Lolium perenne showed a continuous metaxylem element of about 30μ diameter, with only minor restrictions, forming a natural capillary tube. Further, being at the centre of the stele, the metaxylem should persist for some time after the grass has been killed. Hydraulic diameters calculated from laboratory experiments on the rates of water conduction by severed L. perenne roots were in reasonable agreement with the diameter of the metaxylem measured by direct sectioning.Similar experiments on Phleum pratense were more difficult to interpret due to the complexity of the metaxylem, the number of elements not being constant along the root. The rate of water conduction by roots of Dactylis glomeratus was found to be small compared with the other grasses, for although having the largest number of elements they are the smallest in size of any grass examined.The permeability of a severed Lolium perenne root system, calculated on the basis of the surface density of roots found on 4-year-old plots, indicated that the root system should significantly increase the unsaturated permeability of soil at low suctions. To obtain maximum benefit the ‘capillary tubes’ should be severed immediately under the turf and not at ploughing depth. Accordingly, two plots were laid out on old grassland to compare normal autumn ploughing with shallow rototilling on the subsequent germination and growth of spring wheat. In spite of repeated rototilling, however, it proved impossible to kill the grass in the wet winter conditions and the wheat was smothered. A comparison of the suctions developed at 5 cm. in the two plots showed that the unsaturated permeability of the rototilled plot was higher.Although the laboratory results are encouraging there is as yet no conclusive evidence that the natural water supply and drainage system formed by the severed roots is important under field conditions.

Description: The ages of the Clun ewes considered in the survey were ranged from between 1 and 4 years in practicbreeding ally every case. They had thus not attained their maximum fertility which probably occurs at the age of from 4 to 6 years. A consideration of the fertility in the breeding flocks does not provide an estimate of the maximum for this breed, which can only be obtained from older draft ewes which are used in crossbreeding flocks with the object of fat lamb production.Barrenness is relatively unimportant in ewes, but affects approximately one-third of all breeding ewe lambs each year. Abortion was insignificant amongst ewes but was more common amongst ewe lambs.

Description: 1. Trials over 2 years involving 120 Half bred ewes were conducted in outdoor paddocks with controlled feeding. A study was made of the effect of varying the level of feeding during pregnancy on production of ketonaemia and pregnancy toxaemia.2. Blood ketone levels were low and pregnancy toxaemia absent in ewes gaining weight during the latter part of gestation, but ewes failing to gain weight over the same period were subject to ketonaemia and pregnancy toxaemia. A reduction in the ration of fat ewes for a 3-week period, imposed more than 5 weeks before lambing, had no detrimental effect.3. A significant correlation was found between loss in weight and highest ketone figure in the highthroughout and the high-checked groups in 1952 and in the high-checked-high group in 1953.4. High ketonaemia was not always indicative of pregnancy toxaemia, since of the twenty-nine ewes which had, on one or more occasions, over 20 mg. β-hydroxybutyric acid per 100 ml. blood, seven showed signs of pregnancy toxaemia and twentytwo did not.5. In the cases reported, the time of appearance of the first symptoms of pregnancy toxaemia was around 14 days from the estimated lambing date, and affected ewes tended to lamb before term.6. On a comparatively low level of nutrition, only one case of pregnancy toxaemia occurred, though some animals had marked ketosis. In well conditioned ewes reduced to a similar level during the critical period, there was a high incidence of pregnancy toxaemia, and in most of these cases a high degree of ketosis.

Description: The investigations that have been in progress at the Grassland Research Station, Stratford-on-Avon, on the management of grassland for the production of winter pasturage are discussed as four experiments, E 62, E117, E 86 and E158.Exp. E 62 was concerned solely with herbage production, while the remaining three have taken into account the performance of the beef animal under such pasture treatment.The maintenance of condition in the animal has proved possible over a number of winter seasons from 1948 to 1953, sufficiently so to warrant investigation of the means of providing as abundant pasturage as possible at this time of year from latesummer and autumn rested swards. The importance of integrating a system of winter utilization with summer production has become evident in the course of the work, and the necessity of upkeeping sward condition, more especially the grass-legume balance, has been realized. The use of alternate drills of grass and lucerne shows considerable promise in this respect. Intensive utilization and production has taken place from such seedings at all seasons without serious sward deterioration.The development of a grazing system for outwintering cattle destined to be fattened on summer pastures would provide a means whereby such cattle would be fed with as little attention and labour demand as is consistent with good stock management. With the need for cheapening of costs in beef production methods in Britain attention might well be paid to the methods outlined in the light of the experimental data presented.

Description: 1. During the course of investigations on the influence of High- and Low-nutritional planes on the growth, reproduction and production of heifers, sexual activity was studied by recording oestrus data. A total of 239 observations were recorded for fourteen maiden heifers for each nutritional plane; 161 for the High-plane individuals and 78 for those on the Low plane. The investigation included four breeds, viz. Beef Shorthorn, Afrikaner, Friesian and Jersey.2. The average length of the dioestrous cycle was 20·16 days for the High-plane animals, and 20·83 days for their Low-plane counterparts, the difference of 0·67 days not being statistically significant. Breed differences were not very marked, but a tendency was revealed for the Friesians of both planes to have slightly longer cycles on an average than any other breed studied.3. The modal length of the cycle for both groups was found to be 19 days, with 95·6% of the cycles falling within the normal range of 17 to 23 days. Cycles exceeding 33 days in length were, however, excluded from these calculations.4. A tendency was revealed for the initial postpubertal cycles to be longer on an average than what is usually considered the normal length. Although the High-plane heifers settled down to a regular rhythm sooner, observations showed that differences existing between individual animals is probably of greater significance in this regard than any other factor.5. Whereas the majority of the High-plane heifers reached puberty during winter, 85·7% of the Lowplane heifers came on heat for the first time in summer. It is suggested that with the approach of favourable nutritional conditions, animals in a low condition first restore depleted body tissues before the sexual cycle returns to normal activity.6. A slight tendency was noticed for cycle length to vary with the season in the case of the High-plane animals, longer cycles being recorded in summer than in winter. On the Low plane, however, the heifers concerned invariably experienced an anoestrous condition during winter, lasting anything up to 218 days. Only after they regained the losses in live weight, was sexual activity restored as previously pointed out.7. Sexual activity was shown to be greatest in late summer with little variation over the remainder of the year under normal conditions of nutrition and management, while in the Low-plane individuals it fluctuated from complete inactivity in midwinter to a peak in summer.8. Post-partum oestrus was considerably delayed by lactation in the beef animals. The High plane heifers came on heat only after weaning their calves while the Low-plane individuals required nearly a year in addition to regain depleted body reserves before sexual activity was restored. The Low-plane dairy heifers showed a longer post-partum anoestrous period also, the difference between the two groups being 20·77 days.9. The results for the number of services required per conception demonstrated that the Low-nutritional plane caused no detrimental influence on this factor. In fact, the difference existing between the two groups studied was in favour of the Low plane animals. This is in agreement with Asdell's (1952) findings. It was shown that season had no effect on the results obtained.

Description: Eighty-nine Fayomi pullets were classified into three major classes High, Medium and Low according to the intensity of egg laying. Six birds in each class were slaughtered. The major body organs were dissected and weighed. The number and diameter of the visible oocytes were recorded. The dressing out percentage was obtained. The results were as follows:1. During the first year of laying, the averagenumber of eggs laid per day was 0·50, 0·42 and 0·24 eggs for the High, Medium and Low classes respectively.2. There were significant differences in the ovarian weight, length and weight of oviduct, these being highest in the High class.3. The number of visible oocytes was some 200 in all classes. There were, however, differences between classes in the maturation rate of the oocytes as measured by the differences in the diameter of successive ones.4. The weight of blood, feathers, head, wings and legs were higher in the Low than in the High; these are all early maturing organs.5. The weights of the full alimentary canal and the empty gizzard were higher in the High than in the Low, this might be accounted for by a greater appetite and to intake of feed induced by the higher egg production.6. There were no significant differences in the weight of the circulatory, excretory and respiratory organs which are needed for the physiological welfare of the birds.7. The dressing out percentage was higher in the Low and Medium than in the High. This may be due to the greater drainage of nutrients required for high egg production.

Description: 1. 101 Rhode Island Red × Light Sussex chickens have been made to conform to four major changes in the shape of their growth curves from hatching to twenty-four weeks, by control of their plane of nutrition. The four treatments (HH), (LH), (HL) and (LL), allowed comparisons to be made between birds of the same age, but different weights. As the main concern has been to find the essential nature rather than the precise extent of the effects produced by different planes of nutrition, the treatment differences were made as extreme as possible without allowing the rations to become unbalanced.2. Certain individual organs and tissues, the gonads, thyroid and thymus, and the combs and wattles have reacted differentially to the contrasted treatments when compared on a basis of equal body weight. All the organs, with the exception of the very early maturing eyes and heart, have reached significantly different weights on the basis of equal age. Those organs which have yielded treatment differences judged on both the basis of equal weight or equal age have all been late maturing. The results therefore indicate that the effect of treatment has been to restrict the development of the later maturing parts in the case of the low-plane birds, and to accelerate the development of these organs when the birds are reared on the high plane. The results are insensitive to any differential effects which may have been brought about in the early maturing organs, since the design of the experiment did not allow of the slaughtering of birds at equal weight but only at equal age. The means of Comparison of differences at equal weights was the less precise method of ascertaining whether the high- and low-plane regression lines of weight of part to total weight of bird differed significantly the one from the other.

Description: The histochemical localization of acid and alkaline glycerophosphatase (phosphomonoesterase) has been determined throughout the reproductive tract in the bull. Sections were incubated in a buffer substrate containing sodium β-glycerophosphate at pH 4·5 and pH 9·4. Duplicate sections were incubated for progressive lengths of time ranging from ½ hr. (alkaline phosphatase) to a maximum of 48 hr. (acid phosphatase).Evidence of the presence of both enzymes has been obtained in the tissues which compose the reproductive tract. In the case of acid phosphatase the reaction was predominant in the nuclei of the lining epithelial cells. In addition, a positive cellular reaction was found in the distal portions of the epithelium lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. The reaction obtained in the testis appeared to vary with the stage of activity of the tubule.In the case of alkaline phosphatase the reaction was predominantly shown by the basement membrane and the capillaries throughout the tissues with a cellular reaction in the distal portions of the cells lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. In the seminal vesicles the type ‘A’ cells reacted strongly while the periphery of the osmic staining vacuoles of the type ‘B’ cells also gave a positive reaction. The only activity present in the prostate was in the capillary endothelium. The spermatogenic epithelium showed a positive reaction, but no reaction was given by the interstitial cells.

Description: 1. Wheats from manurial trials, whose nitrogen contents differed by reason of the fertilizer treatment applied, have been used as the sole source of protein in rat-feeding experiments.2. Pairs of rats given such diets have shown increased growth when fed wheat of higher nitrogen content.3. Measurement of the ratio of growth rate to nitrogen ingested, suggests that the difference obtained is due, not to increase in the acceptability of the diet, but to the greater nutritive value of the grain from the manurial plots.

Description: 1. The necessity for further information on the digestibility of heather, with particular reference to the effect of age, has been discussed.2. The digestibility of well-defined samples of heather of 4 and 10 years of age has been determined.3. Four-year-old Blackface wethers in crates were fed diets containing 50% of heather and 50% of medium-quality meadow hay.4. The younger sample of heather was found to have appreciably higher digestibility coefficients for all nutritive constituents other than crude fibre.5. Agreement between duplicate sheep in respect of their capacity to digest crude protein was found to be good, and faecal metabolic nitrogen outputs were similar.6. Faecal metabolic nitrogen output was inversely related to the percentage of heather contained in the diet. No relationship between faecal metabolic nitrogen and bulk, as measured on a basis of volume per unit weight, could be established.7. It has been concluded that heather, though inferior as a source of protein, provides rather more energy than a poor-quality meadow hay, and is thus of value as a winter feed.

Description: 1. A series of observations on the grazing behaviour of identical twin cattle on two contrasting systems of pasture management—rotationally and continuously grazed—is described.2. The rotationally grazed cows averaged only 11 min. (day/cow) shorter feeding time and 18 min. shorter ruminating time than their continuously grazed co-twins. The total time they spent in work was thus 29 min. shorter.3. While the average differences in total work over the whole trial was not great, the continuously grazed cows worked for appreciably longer daily periods at the time of seasonal feed shortage during which time the rotationally grazed cows were buffered by their pasture diet being supplemented with silage.4. The differences in grazing behaviour between the cows of the two treatments, together with the magnitude of the seasonal variations which occurred in both groups, indicated that dairy cows attempt to maintain a stable production in the face of adverse pasture conditions by increasing their feeding time.5. Previous conclusions based on observations of uniformly treated twins regarding the importance of heredity in the determination of grazing behaviour were fully confirmed.

Description: 1. Four trials on methods of bloat-prevention vare described: (a) A comparison of ‘break’ grazing and normal ‘rotational’ grazing without restriction of feed in either case. Break grazing observations covered two and five breaks per day.(b) A comparison of these two systems where ‘break’ grazing involved restriction of area available to the cows, and ‘breaks’ varied from seven to eleven per day.(c) Comparison of ‘off and on’ grazing with normal rotational methods in an attempt to force changes in grazing pattern.(d) Comparison of the same pasture grazed at different lengths under rotational grazing methods.2. Grazing behaviour and degree of bloat were noted.3. In general, the results showed that, irrespective of number of breaks, break grazing with or without restriction gave no effective control of bloat.4. There were definite indications that a strictly enforced system of ‘off and on’ grazing could afford considerable practical control.5. Long feed proved definitely safer than feed of the same botanical composition grazed at shorter stages of growth.6. It was found that cows on potentially dangerous grass had short grazing times with few periods of intense activity. Thus, the oft-stated opinion that bloat is caused by cows eating greedily of dangerous pastures was not substantiated. On the contrary, cows on such pasture showed marked reluctance in their grazing activity.7. Bloat-producing swards were also associated with reduced rumination time, even in respect to cows showing no symptoms. Bloated cows showed generally very low rumination times.8. Many of these observations were made on identical twins. From the similarity in their behaviour, it can be concluded that inheritance is an important factor affecting the occurrence of bloat amongst cows grazing the same herbage.9. In the early stages of bloat, ruminal movement and belching increased in frequency and intensity. This is contrary to the theory that bloat is due to rumen atony. Atony was observed only in the advanced stages of the trouble.

Description: 1. Using the method given in the first paper in this series, estimates of p and a have been obtained for farm crops of winter beans grown in 1950 and 1951, p being the frequency of a dominant allele, in this case for black hilum, (1 — α) the proportion of successful fertilizations in which the pollen comes from the same plant as the ovule and α the proportion in which the source of pollen may be any plant in the crop. In the 1950 crop the estimates were in the 1951 crop they were The difference in the estimates of p is not surprising in view of the fact that the two crops were grown from different stocks of beans. The difference in the estimates of α is possibly due to the 1951 crop being much the denser.2. In both crops, as in the case previously reported, selection of high-yielding parents produced a frequency distribution of genotypes showing no influence of inbreeding. The data from the 1951 crop failed to give a satisfactory fit with expectation. Both these facts are unexplained by the simple model of a Mendelian population varying at only one locus and with all genotypes of equal fitness. They can both be explained by amending the model so that the population is considered to vary at several loci and that heterozygotes have a slight advantage.3. Theoretically, a bulk made up of the produce of parent plants selected for high yield should contain substantially more heterozygotes than a bulk of produce of unselected parents. This was confirmed by hilum colour counts. Estimates of yield show that the greater heterozygosity is not reflected in any increase in yield. A possible explanation is offered in terms of information theory.

Description: Part I1. Reasons are given for expressing the evaporative loss of the resting fowl in the following way:where C is a constant, f(tr) is a function of rectal temperature, ps is the vapour pressure of a saturated atmosphere at the temperature of the evaporative surfaces, and pa is the vapour pressure of the ambient air.2. It was found that for practical physiological purposes the rectal temperature may be taken as that of evaporation, from which ps, is deduced. The real temperature of evaporation is probably a few degrees below this, as would be expected.3. It is concluded from this, that atmospheric humidity hinders the evaporative cooling of fowls less than that of men. Therefore, a farmer cannot estimate the comfort of his fowls in hot weather from his own subjective impressions. The experiments also explain theoretically, why evaporative coolers for poultry houses are successful in practice.PART II1. The evaporative loss over a wide range of rectal temperature is plotted in Fig. 1. By applying formula (ii) it was possible to prepare curves for 28 and 5 mm. Hg atmospheric vapour pressure. These vapour pressures are near the extremes of absolute humidity, which fowls naturally encounter in hot climates. Brown Leghorns were used, and it is pointed out that the results with other breeds might not be quite the same.2. It was calculated that part of the increase in evaporative cooling in hyperthermia is due to the rise in temperature of evaporation. At high rectal temperatures its importance is comparable with that of increased pulmonary ventilation.3. There was no significant sex difference in the relation between evaporative loss and rectal temperature (Fig. 2).4. The maximum possible evaporative cooling of fowls in equilibrium with their environment was 41 Kg.cal./sq.m./hr. at a humidity of 28 mm. Hg atmospheric vapour pressure and 64 Kg.cal./sq.m./hr. at 5 mm. This is much less than the maximum attained by man and somewhat less than that of the dog. Although evaporation per unit surface area was less than in the cow, it was much the same in relation to metabolic requirements.5. Next, certain discrepancies are considered in the relation between rectal temperature and evaporative loss (Tables 3–5). At rectal temperatures near the panting threshold evaporation was found to be greater at high air temperatures and during the night. For the night tests fragmentary data only were available. These findings are tentatively attributed to a lower normal body temperature, which lowered the panting threshold.

Description: 1. A small-scale plot experiment which had been carried out from 1947 to 1949 (Holmes, 1951) to study the effect of massive dressings of nitrogen, with and without phosphate and potash, on the yield of a ryegrass dominant sward was continued in 1950–2. A 4 × 4 Graeco-Latin square was used.The nitrogen treatments applied each year were:(1) no nitrogenous fertilizer, (2) 260 lb., (3) 520 lb. and (4) 416 lb. (312 lb. in 1951) nitrogen per acre per annum applied in four or five equal dressings, one for each cut. Treatments 1, 2 and 3 were cut each time they reached the long leafy stage (8–11 in. in height), treatment 4 was cut when 13–16 in. in height.The mineral treatments were (A) no mineral fertilizer, (B) 336–538 lb. K2O per acre per annum depending on nitrogen treatment, (C) 120–180 lb. P2O5 per acre per annum, (D) treatments B and C combined. Mineral applications were applied in four or five dressings each year, one for each cut.2. Applications of phosphate did not affect the yield or protein content of the herbage, but yields were severely restricted in the absence of potash. Where potash was applied the yields under each nitrogen treatment were maintained or increased over the 6-year period. Average yields of dry matter for the 6-year period when potash was present were 4760, 8050, 9620 and 9320 lb. per acre per annum for treatments 1, 2, 3 and 4. Without potash the corresponding average yields were 3980, 5610, 5190 and 5100 lb. Average crude protein yields with potash were 710, 1410, 1990 and 1640 lb. per acre per annum and without potash 550, 1090, 1190 and 1020 lb.3. The presence of potash resulted in earlier growth in each season through the maintenance of the earlier vigorous grasses in the sward. Although the growth curve was variable with treatment 1, treatments 2, 3 and 4 gave nearly uniform distribution of herbage production over the season.4. The weighted mean contents of crude protein for each year ranged from 13·9% for treatment 1 to 20·6% for treatment 3 when potash was given and from 12·9% for treatment 1 to 23·6% for treatment 3 when potash was absent. There was a gradual increase in protein content at the later cuts in each season, but the range was less where nitrogen was applied.5. The efficiency of utilization of fertilizer nitrogen was calculated. When the yield was compared with that of a no-clover sward the average response was 15·6, 10·8 and 11·8 lb. dry matter per lb. of nitrogen applied for treatments 2, 3 and 4 respectively. In terms of crude protein the percentage recovery was 53, 44 and 42 respectively. When the yields were compared with those of the clovery swards the nitrogen recovery figures were reduced by about one-third.6. The botanical composition of the plots was determined by the nitrogen and potash treatments. Where both were adequate a vigorous sward of ryegrass and timothy was maintained. Where nitrogen was absent but potash present a clovery sward developed. In the absence of potash with or without nitrogen the better grasses declined and were replaced by poor grasses.7. Provided potash was applied there were no marked changes in the soil analysis.8. The results are discussed with particular reference to the maintenance of high grass yields and the relative roles of clover and fertilizer nitrogen.

Description: An experiment has been performed on the effect of sulphanilamide on the calcium and phosphorus metabolism of laying hens.The results showed a decrease in calcium retention and thinner shelled eggs, when sulphanilamide was fed.When the drug was withdrawn the birds took some time to reach normal balance values again, but they immediately produced normally shelled eggs.The results of this experiment, along with a previous experiment, have been considered from other points of view in an attempt to find an explanation of some slightly divergent results. Relationships between calcium retained and calcium in shell and between calcium balance and phosphorus balance have been found and the values for changes in calcium bound to phosphorus and residual calcium in bone have been calculated. These considerations have helped to clear up the discrepancies, and it would appear that sulphanilamide effects may be influenced by season, and by calcium and phosphorus intake.

Description: 1. An investigation has been made into the changes that take place in the free amino-acid pattern when kale-water slurries are allowed to ferment under conditions of (a) aeration, (b) anaerobiasis and (c) partial sterilization with sulphur dioxide.2. It has been found that, with aerated mixtures, the loss of free amino-acids is virtually complete within 2 weeks, while there is only a slight loss with the anaerobic mixtures. With mixtures containing sulphur dioxide no loss of amino-acids occur.3. The formation of α-amino butyric acid possibly from threonine has been noted.

Description: 1. Egg-shells from six inbred lines of Brown Leghorn fowls were examined for porosity and thickness in March and in July.2. For both characters studied the variation between-line means was found to be significant.3. The line means for thickness were with a single exception lower in July.4. Porosity coefficients increased from March to July.5. No significant relationship between shell thickness and porosity was found in either season. Line differences in porosity values are therefore attributable to variations in other properties of the shell.

Description: In the course of two breeding seasons 261 mature Romney ewes have been employed in three slaughter experiments designed to investigate the manner in which the reproductive performance of such animals, after treatment with a single injection of P.M.S., is conditioned by: (a) the amount of P.M.S. administered; (b) the nutritive status of the treated animals; (c) the stage of the oestrous cycle at which the P.M.S. is administered.In the first experiment, one untreated control group and three experimental groups of ewes, treated with different amounts of P.M.S., on the twelfth and thirteenth days of the cycle, were used to establish a dose level-ovulation response relationship. Mean ovulation rates and ranges of ovulations observed were: control 1.17 (1–2); 250 i.u. P.M.S. 1.50 (1–2); 500 i.u. P.M.S. 2.07 (1–3); 1000 i.u. P.M.S. 4.33 (1–13).In the second experiment, oestrous cycle lengths, ovulation and conception rates, and loss of ova during the first few weeks of pregnancy were compared in four groups of ewes that had been treated as follows: (a) neither flushed nor treated with P.M.S.; (b) flushed but not treated with P.M.S.; (c) not flushed but treated with 650 i.u. P.M.S. on the twelfth or thirteenth days of the cycle; (d) flushed and treated with 650 i.u. P.M.S. on the twelfth or thirteenth days of the cycle.Oestrous cycle lengths were of significantly shorter duration in flushed than in unflushed ewes (0.5 day) and in P.M.S.-treated than in untreated animals (0.7 day). Conception rates were of a normal order in all four groups. The mean ovulation rates of those that conceived at first fertile service were respectively 1.33, 1.61, 1.80 and 1.88. The number of ovulations ranged from 1–2 in the unflushed–untreated group and from 1–3 in each of the other three groups.In the third experiment results obtained from groups of ewes treated with 650 i.u. P.M.S. on the tenth, eleventh, twelfth, thirteenth and fourteenth days respectively, were compared. Mean ovulation rates were approximately similar in all five groups, but (as was also the case in the second experiment) of a lower order than might have been expected from the dose response curve established in the first experiment. Conception rates were satisfactory after injection on the twelfth, thirteenth or fourteenth days, but unsatisfactory after treatment on the eleventh day, and still less satisfactory after treatment on the tenth day.From the results obtained in these three experiments the following general conclusions were drawn:(1) Breed or strain differences may be of considerable importance in governing the extent of the ovulation response following P.M.S. treatment.(2) The magnitude of the ovulation response to P.M.S. treatment depends to some extent on the ‘batch’ of P.M.S. used and/or the strain of ewes employed.(3) The nutritive status of ewes during the breeding season is not an important factor in determining the ovulation rate following P.M.S. treatment.(4) When P.M.S. is administered 5 days or less before the onset of the subsequent oestrus, good conception rates are obtained.(5) Extremely poor conception rates result where animals are treated more than 5 days before oestrus.(6) Best ovulation and conception rates are obtained when the treatment-to-oestrus interval is 2–3 days.(7) For optimum results, treatment on the fourteenth day of the cycle is recommended. However, good results are also obtained after treatment on either the twelfth or the thirteenth days. Treatment on the fifteenth day should also be reasonably satisfactory.(8) When ovulated in similar numbers, and provided conception occurs, ova produced as a result of P.M.S. stimulation are no more prone to fail to undergo normal embryonic development than are naturally ripened eggs.

Description: It is known that acidic red lateritic soils are usually deficient in available phosphorus, and whenever any soluble phosphates are added to such soils they become fixed and non-available to plants. It is believed that added phosphates make insoluble compounds of ferric phosphates with iron salts in the ferric state. Since ferrous salts are more soluble than the ferric salts, it suggests itself that if in the soil we can keep the iron in the ferrous state or can effect the conversion of ferric salts into ferrous salts it may be possible to reduce the formation of insoluble iron salts with phosphorus and thus increase the amount of available phosphorus by reducing phosphate fixation. With this object in view red latoritic soils from Dacca Farm area were kept under water-logged condition and the effect upon the conversion of Fe3+ into Fe2+ state and the change of readily soluble phosphorus were studied from time to time.

Description: 1. A survey and. statistical analysis of the records of litters born in the N.I.R.D. herd of Large White pigs over a period of 16 years are presented.2. The mean length of gestation was 114 days for both gilts and sows.3. The mean numbers of pigs born alive and born dead per litter from gilts, 10·0 and 0·2 respectively, were both significantly smaller than the corresponding figures for sows, 11·8 and O·8. No seasonal differences were found.4. The mean total losses of pigs from birth to weaning at 8 weeks were 29·5% of pigs born alive. The losses in litters from gilts, 23·0%, were significantly smaller than in litters from sows, 31·0%. The losses during the winter months both for gilts, 32·5%, and for sows, 35·9%, were significantly higher than during the summer months, 19·4% and 26·7% for gilts and sows respectively.5. Over 50% of the total losses were due to crushing by the dam, 74·1% of the losses from this cause occurring during the first 48 hr. after birth.6. The mean number of pigs weaned per litter was 8·0. The difference between the number weaned per litter from gilts, 7·7, and per litter from number of pigs was weaned per litter from sows during the summer months, 8·7, than during the winter months, 7·4.7. There was no significant difference between the number of male and of female pigs weaned.8. The mean weight at weaning was 29·9 lb., male pigs, 30·3 lb., being significantly heavier than females, 29·51b. Pigs in litters from gilts, 27·81b., were significantly lighter at weaning than those from sows, 30·0 lb., and for both gilts and sows, pigs reared during the summer months, 29·7 and 31·8 lb. respectively, were significantly heavier than those reared during the winter months, 25·9 and 28·2 lb. respectively.

Description: 1. The relations of yolk, albumen and egg weight were studied in seven inbred lines of Brown Leghorns and reciprocal crosses of two of these lines.2. In all the lines the eggs produced by hens had a bigger proportion of yolk than those produced by pullets.3. Besides changes in both components accompanying differences in egg size the line means for albumen weight still differ significantly after adjustment is made for its covariance with yolk weight. This independent variation leads to differences in the yolk-albumen ratio of the hens.4. Within the lines there is a significant negative association between egg size and the yolk/albumen ratio.5. The wide differences in egg size, dividing the pure lines into two groups characterized by large and small eggs respectively, resulted from a marked decrease in the amount of albumen in the eggs of the latter group. Yolk weights, on the other hand, could be ranked in a fairly regular series with adjacent lines differing by 2 g. or less.6. There is some source of variation in the yolk/ albumen ratio for line means which is not accounted for by differences in egg size.

Description: 1. Follicular fluid was collected by aspiration from the ovaries of cows which had been treated with pregnant mare serum, and were killed 3–4 days after heat.2. Various chemical determinations have been carried out with samples of follicular fluid which, amongst others, was found to contain 39–43 mg./ 100 ml. of glucose, between 13 and 95 mg./100 ml. of lactic acid, and 0·8–3·0 mg./100 ml. of ascorbic acid.3. The effect of follicular fluid upon sperm fructolysis was examined; however, no effect other than that due to the glucose content of the follicular fluid, could be observed.

Description: Records of plant development in some twenty-five multifactorial experiments were collected with the object of analysing the effects of nutrient level, density, spatial arrangement and variety on seed production in linseed. By sampling techniques estimates were made of plant density, the extent of basal branching, the number of capsules per stem, the number of seeds per capsule and the seed weight. The expected plot yields, calculated from these data, were in good agreement with the harvested yields.In factorial trials, involving additions of nitrogen, phosphorus and potassium, only a change in the nitrogen level increased the yield of seed, and this gain was largely determined by an increase in the production of capsules and not by any alteration in either the number of seeds per capsule or the seed weight.Over a range of density of thirty to eighty plants per square foot the number of capsules produced per plant was inversely correlated with density. When the distance between drills was maintained at 6–7 in. and the density varied by changing the seed rate then—on an area basis—both capsule production and seed yield were rarely affected since the product of plant number and capsules per plant remained relatively constant. On the other hand, if the rate of seed delivery in the drill was kept the same and the distance between the drills was the variable for density then with a narrow width of drill (4 in.) the increase in plant density more than offset the fall in capsules per plant.Further experiments comparing drilling and crossdrilling did not wholly confirm the importance of spatial arrangement. There was, however, evidence that at densities over eighty plants per square foot, besides a further reduction in capsules per plant, the number of seeds per capsule was depressed. Varieties were characterized by differences in seed size, the number of seeds per capsule, capsules per plant and the ability to produce more capsules at high levels of nitrogen. The superiority of the yielding capacity of Royal could be ascribed to the high rate of capsule production. Such varietal differences in capsule production have not been reported previously, and since the number of capsules per plant is greatly influenced by varying density, the common practice of basing selection on spaced plants, may not give a true assessment of capsule formation at densities optimal for seed production.

Description: 1. A series of grazing behaviour observations on 10 sets of lactating identical twins is described. Four fortnights distributed over the main lactation period were covered. In three of the fortnights, the observations were made on six 24 hr. periods, while in the remaining fortnight the cows were observed on all 14 days.2. Anoutstanding feature of the grazing behaviour of dairy cattle is its variability, due to external and internal conditions.3. Of the external factors, climate (in a temperate zone) is relatively unimportant.4. The quantity and quality of the herbage offered are of importance in modifying the grazing behaviour of dairy cattle. Under adverse pasture conditions there is, in general, an increase of total working time (grazing + ruminating): grazing time increases with scarcity of herbage and with mixed quality, while ruminating time is prolonged by poor quality grass.5. Ruminating time is strongly dependent on the quantity and quality of the ingested grass, but the relationship is, for various reasons, obscured in a field trial such as the present.6. The adaptation of grazing habits to new conditions is very rapid.7. Feed requirement for milk production is the most important internal factor determining variation in the length of grazing time.8. Inheritance × environment interactions as a source of variations in grazing times are due to the following factors:(a) Differences amongst twin sets in lactational persistency, which presumably cause parallel differences in feed requirements.(b) Differences in the response of high and low producing twin sets to varying pasture conditions.(c) Non-analysable idiosyncrasies common to the members of some twin sets.9. Twin sets graze and ruminate at a characteristic rate.

Description: 1. The1951 clover experiment. No significant effects on the mean yield of nectar were obtained, but the higher dose of phosphate significantly increased the frequency of zero samples during August, the main flowering and sampling period; so also did the higher dose of potash in the presence of high nitrate. In general those treatments which depressed nectar secretion resulted in a larger proportion of flowers opening before mid-August. Accelerated flower production appeared to result from more rapid growth during August.2. The 1952 clover experiment. The treatment effects on quantity of sugar per floret were compared with those on final stem weight. Treatment effects on sugar/floret on particular sampling occasions were compared with the effects on relative ‘growth rate’ during the preceding period. Additional phosphate always resulted in greater and more rapid growth, but it only reduced the nectar yield in the presence of the highest level of potash. In the presence of low doses of potash nectar secretion was consistently poor. Additional potash did not increase the nectar yield if it resulted in greater or more rapid growth; if it did not affect size or growth rate it increased the nectar yield. Clonal differences in nectar production were greater than treatment ones.3. The responses of the four species used in this series of experiments are compared. The results of other workers on the effects of fertilizer treatments on nectar production are discussed in relation to those reported here. If the balance between different fertilizers and their effects on growth are considered, as well as nectar yields, contradictions between the results of various workers can be explained. It is suggested that when potash tends to limit growth nectar secretion is likely to be consistently poor, but that when growth tends to be limited by nitrogen or phosphate a relative surplus of potash will promote good secretion.Reference is made to work on the relation of the sugar supply in plants to nectar secretion and on the relation of fertilizers to the sugar supply. Tentative recommendations are made which require confirmation in field tests.

Description: 1. Experiments were carried out to test the effects of the three main mineral fertilizers on the secretion of nectar by apple, mustard and buckwheat. Factorial designs were used, and data on plant growth were collected in order to attempt to relate growth to nectar production. Apart from the apple trees the plants were cultivated in clean sand to which known quantities of pure minerals were added.2. Apple. The mean quantity of sugar per flower was significantly increased by extra potash; phosphate also tended to increase it. At the higher level of potash, nitrogen had significantly increased the crop of apples the previous year; it decreased the nectar yield. Potash increased nectar yield most when its effect on the crop had been small, and vice versa.3. Mustard. In this experiment the quantity of water supplied to the plants was varied as well as the fertilizers. On the last sampling occasion nectar was more frequently obtained from plants with the lower dose of nitrate than from those with the higher dose. At the high level of water, and with low nitrate, extra potash consistently increased the mean quantity of sugar per flower but with the high level of nitrate it consistently decreased it. The phosphate level had no significant or consistent influence on nectar yield.Treatments increasing nectar production tended (a) to decrease stem weight and total number of flowers; (b) to retard flower production, probably as a consequence of relatively slower growth; (c) to increase petal length, and (d) to increase the proportion of plants with orange or red pigment in the withering leaves.4. Buckwheat. Nectar was obtained significantly more frequently from those plants which had received extra nitrate and extra potash. It is suggested that the nitrate effect was due primarily to the senescent condition at the time of sampling of some of the plants with the lower dose, especially those which also had the high level of phosphate, and to the interactions of nitrate with phosphate and potash in respect to nectar production. Such explanations do not account for the effect of extra potash. Extra nitrate and potash always increased the stem weight and number of flower sprays; phosphate had little effect.

Description: 1. A feeding trial is described including four groups of cattle fed on silage only, two mixtures of silage and roots, and roots, straw, hay and oats.2. The live-weight gains made are recorded together with the rate of dry-matter intake.3. The efficiency of the dry matter of the diets was calculated.4. Silage fed alone produced a significantly greater rate of fattening than the other three diets.5. Cattle receiving roots in the morning and silage at night consumed 10·78% more dry matter and made greater live-weight gains than cattle fed on silage in the morning and roots at night.6. Calculation of the starch values of the roots and silage showed that these are higher when fed together than when silage is fed alone or when roots are fed with straw, hay and oats.7. An experiment is described designed to determine the effect of the dry-matter percentage of the diet on dry-matter intake in ruminants and of sudden changes in dry-matter content on digestibility.8. Sheep receiving 19·46% dry-matter silage consumed 16·7% more dry matter and 19·8% more starch equivalent than sheep eating 15·85% dry-matter silage.9. When the dry-matter percentage of the silage fell from 19·46 to 15·77 the digestibility of the dry matter fell by over 10%.10. The starch equivalent of the silage when fed alone was determined from the results of a digestibility trial and according to the performance of the cattle in the feeding trial. The values found were 65·88 and 66·15% respectively.11. The losses suffered in silage-making in twentyfive silos are recorded and discussed. The loss of dry matter and crude protein both average approximately 40% of that ensiled. The need for finding methods of reducing these losses is again stressed.

Description: 1. Studies were made during the 1951 and 1952 seasons of the oxalate contents of the leaves of mangolds, sugar mangolds and fodder sugar beet.2. In all varieties greater concentrations of total oxalates were found during the summer months, the amounts diminishing gradually as the season advanced. Up to 12% was found in the dry-matter of mangold leaves and 9% in fodder sugar-beet leaves in July, these levels falling to 3% by mid-winter. There is some evidence that these changes are due in part to loss of outer leaves.3. Roughly one-third of the oxalates are present in water-soluble form. The addition of 1 part of chalk to 1000 parts of leaves, as has been generally recommended, is theoretically sufficient to render unavailable the soluble oxalates present during winter, but insufficient for leaves fed earlier hi the season.4. A number of observations showed small reductions in the soluble oxalate contents of the leaves due to wilting, but there were exceptions to this, and these appear to be related to sampling periods rather than to varieties.5. Insoluble oxalates appear to be unaffected by wilting and may show apparent increases in amount due to respiration losses of labile leaf constituents. The insoluble/soluble oxalate ratio is thus changed by wilting.6. It is suggested that the undesirable effects sometimes resulting from the feeding of beet leaves to livestock may not be due to oxalates, but that other factors present, which are labile during wilting, may be involved.

Description: 1. Details are given of the construction of one open-circuit and two closed-circuit respiration chambers suitable for the determination of the 24 hr. exchange of energy of calves or of other animals weighing up to 75 kg.2. Gas analysis apparatus and the general technique employed in experiments with the closedcircuit apparatus are described.3. From experience gained with both types of apparatus the closed-circuit apparatus is preferred for its simplicity and ease of working.

Description: The experiment reported here involved thirty-two pigs from birth to bacon weight. During the 9 weeks before weaning sixteen pigs were reared on damp cold floors in a cold building and sixteen were reared on dry cold floors in the same building. After weaning all the floors were kept dry.Before weaning four out of the sixteen pigs in each treatment died, but only one, which was in the wet cold floor group, was suspected of having a liver disease which has been described by Naftalin & Howie (1949). A greater incidence of this disease was expected to occur under the cold environmental conditions of the experiment.After weaning one deformed pig was killed and three other pigs were killed at 40 weeks old. The latter three all had the liver disease. There was evidence that the disease had developed after the pigs were weaned and this indicated that it cannot necessarily be prevented by the provision of dry conditions in a cold house. The growth curves of two of the three pigs fitted the hypothesis that the disease is associated with cold environmental conditions, but the growth curve of the third suggested that it might have contracted the disease during the summer when the minimum air temperature was 54° F.The possibility was discussed that the liver disease is caused by a virus or low nutritional status interacting with the effects of cold environmental conditions.The two pre-weaning treatments had no dissimilar effects upon the piglets' weaning weights, blood haemoglobin levels and appetites for solid food, nor did they have any differential effect upon the growth rates and efficiencies of conversion of food to flesh of the pigs which survived to bacon weight. The bacon carcasses from the pigs born and reared to weaning on wet cold floors were shorter and fatter than those from pigs born and reared on dry cold floors. No explanation could be offered for this difference in carcass conformation.The rates of heat loss from a constant temperature water-bath to an uninsulated concrete floor upon which pigs had not lain were halved by the provision of ½ in. depth of chopped straw bedding. They were also halved if the measurements were taken after pigs had recently been lying on the bare floor, and under these circumstances the provision of ½ in. depth of chopped straw bedding cut the heat losses even further.

Description: 1. The construction and performance are described of a simple climatic chamber for work on poultry in hot climates. In addition, brief reference is made to an improved ventilation system and to refrigeration equipment fitted to chambers of later design.2. Air temperature and humidity may be controlled over a fairly wide range above that of the external air. Radiant temperature is maintained close to air temperature. The air movement averages about 20 ft./min. in the working space.3. The apparatus is suitable for accurate tests of heat tolerance lasting for a few hours, or for longterm experiments.4. It is suggested that the provision of climatic chambers for use with farm animals in underdeveloped agricultural areas is not a formidable problem.

Description: 1. The development of the fleece and follicle population was studied in six Herdwick and two Herdwick × Swaledale sheep on their native farm in Cumberland. Six of these sheep survived the first 14 months of the experiment, and four were kept under observation for a further 12 months. Growth in body weight, body surface area, and area of tattooed squares was recorded and discussed.2. Fibre type arrays (at the mid-side positions) were ‘Plateau’ in all but one of the pure Herdwick lambs, and ‘Saddle’ in the remaining three animals.3. The earliest fibres of the array (halos and coarse super-sickles) were mostly ribbon-shaped in their pre-natal and early post-natal portions, below which they became cylindrical. These fibres were ‘birth coat kemps’ and were shed about 10 weeks after birth. At this time later-developed fibres (sickles and curly-tips) showed ‘crisis thinning’ but did not shed, whilst late curly tips and histerotrichs were not affected. These three groups gave rise to three corresponding groups of fibres in the adult fleece, namely kemps, hairs and fine fibres.4. Two generations of kemp fibres were grown each year, ‘spring kemps’ commencing growth about April and shedding by July; and ‘autumn kemps’ commencing growth in July and forming ‘brush-roots’ in the autumn and early winter, although the majority remain in their follicles until the following spring.5. The majority of the curly tip fibres of the birth coat grow into long hair fibres, which are of hetero-typical shape. In summer they are more or less coarse, and medullated, whilst in winter they become fine and lose their medulla; many cease growth during the middle of the winter period after producing a short length of fine fibre, and commence growth again in the spring. The late curly tip and histerotrichs fibres continue to grow as the fine undercoat fibres of the fleece, without any medullation.6. A large proportion of both primary and secondary follicles shed their fibres during the winter months. When this proportion is sufficiently high this leads to a severe ‘winter break’ in the wool staple. The visible ‘break’ is the result of the combined effect of the winter fining of heterotype hairs and the shedding of some of all types. Fibres traversing the break were found to be either long heterotypes or long fine fibres.7. The adult colour of any individual Herdwick sheep is the result of the interaction of several factors of which the main ones are: (1) later fibre types tend to be less pigmented than early types; (2) less vigorous growth of an individual fibre tends to reduce its pigmentation; (3) a more or less extensive acromelanic pigmentation; (4) the white areas may be affected by various degrees of speckling or roaning; (5) the kemp-like hairs of the face and legs are black at birth, and these are eventually shed and replaced by similar but unpigmented fibres.8. Numerical data on the fibre and follicle population are presented. The mean proportion of the three main fibre types (all sheep, all seasons) was: coarse 18%, medium 25%, fine 59%. The mean adult follicle density was 1012 per sq.cm. and the mean adult S/P ratio was 3·37:1.

Description: 1. Birds fed on rations devoid of animal byproducts from hatching until 18 months of age were equal in laying performance and health to those that had received animal supplements.2. The stimulation of early growth by feeding aureomycin did not affect the final weight of pullets, their egg production or the incidence of broodiness.3. The ‘animal protein factor(s)’ was of limited importance for egg production. There was a suggestive indication of an effect of a deficiency of the factor(s) when birds on an all-plant ration had been laying for 6 months without access to their droppings. Limited access to ‘unfermented’ droppings, which provided the only dietary source of the factor(s) during both rearing and laying periods, was sufficient to meet the need of the birds for sustained egg production.

Description: 1. The results of six trials have been examined in which pigs received rations with contrasting levels of crude fibre. The contents of crude fibre ranged from 3½ to 11½% and were related to a variety of basal diets.2. The main object of the trials was to study the effect of increased levels of dietary crude fibre on carcass conformation, under conditions where there was no disparity in rate of live -weight gain between the pigs receiving the higher and the lower level of fibre. Thus pigs on the high-fibre diets received extra food in order to equalize the intake of digestible nutrients.3. The results indicate that a rise in the level of dietary crude fibre was accompanied by a fall in the killing-out percentage, and hence by lower carcass weights. This effect was produced even by comparatively small changes, such as a rise from 3½% crude fibre to about 5% crude fibre. The results also show that carcass weight was positively correlated with back-fat thickness to a marked degree.4. It is evident that raising the level of crude fibre in the food caused a change in the distribution of live-weight gains, so that when at the same slaughter weights, the high-fibre pigs had lighter carcasses and heavier offal than their low-fibre counterparts. Consequently the high-fibre pigs also had thinner back-fats, and they would tend to grade better under carcass grading systems based on backfat measurements and biased towards thin back-fats.5. It is suggested that these effects are likely to be produced even in pigs considerably advanced in fattening, and that in younger pigs the drawback of retardation in rate of live-weight gain may also be encountered. Thus the use of high-fibre diets in self-feeding systems, as a corrective against over-fatness, may not normally be the best means of attaining this objective under commercial conditions.

Description: A two-row hand-dropping potato planter was modified by adding fertilizer equipment. The machine was used in thirty-three experiments in 1951 and 1952 to plant potatoes from flat land and compare broadcast dressings of granulated compound fertilizer with dressings placed near to the seed.Fertilizer placed either in one band at the side and below the level of the seed, or in contact with the seed, gave consistently higher yields than broadcast dressings. Broadcast fertilizer gave yields similar to those given by only one-half to two-thirds as much placed fertilizer. On the average of all the experiments, placing fertilizer gave about 1 ton/acre more potatoes than broadcasting. The advantages of placement were greatest when low rates of dressing were used.Broadcast fertilizer was cultivated deeply into the seed-beds in nineteen experiments in 1952 and gave slightly lower average yields than late dressings broadcast on the seed-beds.Fertilizer placed in bands on the soil surface immediately in front of the seed-shoes gave yields similar to those given by dressings broadcast over the seed-beds in fourteen experiments in 1951. In average planting conditions fertilizer broadcast on the seed-beds or placed in front of the seed-shoes was thrown to the middle of the ridges and concentrated above the seed.Fertilizer placed in contact with the seed gave higher average yields than dressings in a sideband at both rates of manuring in the 1951 experiments. In 1952 contact placement was slightly superior to sideband placement at low rates of fertilizer and slightly inferior at high rates. In most experiments in each year emergence was delayed by 10–14 days when the heavy dressing was placed in contact with the seed. Early growth was poor but at most centres the crops recovered later in the season and gave good yields. There is most risk of damage from contact placement on light soils, on badly prepared seed-beds and in dry years. Dressings of 10 to 12 cwt./acre of ordinary-strength compound fertilizers are likely to be quite safe when applied in contact with the seed. If heavier dressings are to be used, part should be applied in contact with the seed and part broadcast, such split applications were satisfactory in experiments in 1951.Farmers planting even moderate acreages of potatoes by machines will benefit by using a suitable fertilizer attachment. Equipment is needed to place fertilizer at the side of the seed so that heavy dressings can be used to secure maximum yields without risk.

Description: A study has been made of some of the nitrogen fractions of the pegasse soils of British Guiana in virgin and exhausted conditions, that is, before and after cropping.1. Preliminary field experiments on the virgin and exhausted soils adduced strong evidence in support of the complaints made by farmers that the productivity in yields of the pegasse soils after continuous cropping for a comparatively short period is considerably impaired.2. The virgin soil showed an appreciable amount of nitrate nitrogen, while the exhausted sample indicated no nitrate. The latter soil, on the other hand, contained a higher amount of ammonia nitrogen measured by KCl extraction than the former soil.3. Nitrification studies with added ammonium salts indicated that under optimum conditions the nitrifying power of the exhausted soil was extremely low. Additions of sodium nitrate indicated that the nitrate was partially reduced to ammonia by the worn-out pegasse soil. The virgin pegasse, on the other hand, showed an appreciable rate of nitrification.

Description: 1. The numbers of Streptococcus bovis in the rumen of a heifer and a steer, each having a permanent rumen fistula, were shown to remain relatively constant within the range 105 to 107 per ml. rumen liquid (strained rumen contents) over a period of more than 3 years.2. The numbers of Strep. bovis were little affected by the change in diet from stall-feeding (oats, beans, hay and straw) to grass or vice versa.3. There was a slight increase in the numbers of Strep. bovis following each meal when the animals were stall-fed, but no appreciable variation in numbers throughout the day when the animals were at grass.4. Strep. bovis has also been isolated from the rumen of freshly slaughtered cattle and sheep from different parts of the country, from the rumen of goats and calves and from the faeces of cattle, goats and in small numbers associated with Strep. equinus from horse dung.5. Strep. bovis was found in the contents of the omasum, large intestine and caecum of three cattle, but in the small intestine of only one of these animals. Very small numbers of Strep. bovis were detected in the abomasal contents of only four of twelve animals examined.6. The characteristics of these strains of Strep. bovis have been described. The synthesis of an iodophilic polysaccharide by Strep. bovis has been demonstrated.7. A possible role of Strep. bovis in the decomposition of starch and other carbohydrates in the rumen is discussed.

Description: 1. Twenty ejaculates were collected from the same boar at weekly intervals; the composition of semen was studied by microscopic and chemical methods. The total volume of ejaculates varied from 240 to 500 ml., and sperm concentration from 50,000 to 177,000 cells/μl. Chemical analysis revealed 2·4–12·6 mg./100ml. fructose, 5·9–23·1 mg./100 ml. ergothioneine, and 32–156 mg./100 ml. citric acid.2. The sequence with which the different parts of boar semen follow one another at ejaculation was studied by the method of fractionate collection. The earliest to be emitted was the ‘pre-sperm fraction’ from which sperm and seminal vesicle secretion were absent. The next was the ‘sperm-rich fraction’ which showed not only a high sperm content but contained also substantial quantities of substances derived from the seminal vesicles, i.e. fructose, ergothioneine and citric acid. The ‘post-sperm fraction’ consisted mainly of accessory gland secretions.3. The analysis of semen fractions collected at very brief intervals has shown that whereas the secretion of the seminal vesicles accompanies the spermatozoa at ejaculation, it attains its maximum immediately after the bulk of the sperm has been ejaculated.

Description: 1. Tests have been carried out to investigate the hydrolysis of phytate in wheat, bran, and oats.2. Oats showed practically no phytase activity.3. Wheat phytase had an optimum pH of 5·0–5·1 and functioned at pH values down to 3·0. When hydrolysis had been arrested by acidifying to pH 2·5 for 5 min. or longer, the phytase did not recover when the pH was raised to 5·0 by the addition of sodium bicarbonate.4. There was an almost uniform increase in the rate of hydrolysis between 15 and 50° C.5. The rate of phytate hydrolysis decreased as the reaction proceeded, but the reaction continued until only a very small amount of soluble substrate remained.6. The presence of calcium, under conditions in which it could form insoluble phytate, reduced phytate hydrolysis to a considerable degree.7. These reactions are considered in relation to phytate hydrolysis in the digestive tracts of animals.

Description: 1. The precipitation of calcium, magnesium, phytate phosphorus, and non-phytate (chiefly phosphate) phosphorus has been determined in ‘hydrolysed’ and ‘unhydrolysed’ bran, with varying amounts of added calcium as calcium carbonate.2. It was found that calcium phytate was precipitated before non-phytate (chiefly phosphate), whatever level of calcium carbonate was added.3. Precipitation began and was more complete under more acid conditions when calcium and Ca: P ratio were high.4. Similar experiments have been carried out using salt solutions containing calcium and phytate, calcium and phosphate, and calcium, phytate, and phosphate. The results were similar in most cases to those of corresponding bran mixtures.5. The above results have been considered in relation to the precipitations which are likely to occur in the small intestine, and the possible effects of these precipitations on absorption are discussed.

Description: 1. The solubilities of calcium, magnesium and phosphorus in bran, wheat, oats and certain mineral supplements have been determined at pH values between 6·5 and 1·0.2. The solubility of calcium in calcium carbonate varied with the cereal present, but it was always completely soluble at pH 3·0 and below.3. The calcium present in bran and wheat was not readily soluble; that in oats was fairly readily soluble.4. Magnesium dissolved more readily at higher pH values than calcium.5. Phosphorus in bran (with or without added calcium), and that present as pure salts, was almost completely dissolved at pH 3·0 and below, but very low phosphorus solubilities were found at these pH values in oats and, to a lesser extent, wheat.6. These results have been considered in relation to the acidification of food which occurs in the true stomach.

Description: This paper, which forms part of a series of investigations on the potato crop, presents evidence obtained from experiments reported in the literature on the relation between seed rate and yield of maincrop potatoes. The available experiments are sufficient to indicate what is the average relationship between seed rate and yield, but are insufficient to demonstrate any clear differences between different parts of the country, soil types or even different varieties.Using this average relationship, optimum seed rates are presented for a range of prices of seed and produce. These optimal rates are compared with estimates from surveys of the actual amounts planted by growers in different parts of the country.Provided the optimum seed rate is attained the precise combination of seed size and spacing distance appears to be of minor importance; that is, a grower should aim to plant at the optimum seed rate regardless of seed size. There is, however, an upper limit of spacing between sets which should not be exceeded however large the seed may be.The optimum rate of planting at 1952 prices of ‘A’ or ‘H’ certificate seed is estimated to be 16–17 cwt. in most of the main potato-growing areas of the country, though it may be a little higher where a grower has a market for once-grown seed. Surveys indicate, however, that the normal planting rate of certified seed is over a ton to the acre in these districts.For a grower's own once-grown seed, on the other hand, for which the cost is not more than the price received for ware, the optimum seed rate is at least one ton per acre, whilst the average weight of seed actually planted is only about 17 cwt. per acre. It is estimated that the average loss per acre due to this failure to plant at the optimum seed rate amounts to 20–25s. per acre planted with certified seed and 10–15s. per acre for once-grown seed.

Description: 1. Past work on muzzle patterns of individuals and of twins is reviewed.2. A technique of obtaining muzzle prints by making plaster casts is described.3. Using casts, muzzle patterns from one-egg and two-egg twin pairs were scored for similarity on a 1– 5 scale. Patterns of one-egg twins were significantly more similar than those of two-egg twins, and the largest part of the total variance was due to the difference between these two groups. The score distributions for monozygous and dizygous twins did not completely overlap, indicating that muzzle pattern is inherited. However, the extent of overlap observed confines the usefulness of muzzle pattern in twin diagnosis to confirmatory evidence at the extremes of the similarity scale.4. Parts of the muzzle pattern (central groove, cell length, and cell margins) were judged on an arbitrary scale. Two-egg twins were not found sufficiently less similar than one-egg twins for the characters to be useful in diagnosis. Twins were more alike than random pairs, but significantly so only for central groove and MZ cell length.

Description: 1. The seasonal variation of farm sales of milk was measured for each year from 1937– 8 to 1951– 2 for England and Wales, and for each of the eleven marketing regions into which the country is divided.2. The effect of changes between years in the amount of seasonal variation in milk values on the amount of seasonal variation in sales was examined and little direct connexion found.3. Despite the fact that high milk prices in winter do not make production at that time more profitable, farmers get their cows to calve when prices are rising or are at their highest.4. An inverse correlation was found between the number of calves born alive and sales of milk in the same month, but a positive correlation between the total number of cows in milk and the volume of sales in the same month.5. That part of seasonal variation in sales which cannot be explained by variations in the number of animals in milk was shown to be mainly due to variations in the shape of lactation curves of animals calving in different months.6. The importance of feeding, particularly the availability and condition of grass, in affecting the shape of the lactation curve is discussed.

Description: 1. Ruminal ammonia concentrations were measured in sheep receiving basal diets of hay and meals with various supplementary sources of protein. Ammonia production from groundnut meal was great and from maize products slight. Herring meal behaved in an intermediate way.2. The extent of ammonia production from a given amount of protein-rich material was decreased when the amount of starch or cereal meal fed at the same time was increased.

Description: 1. Herring-meal supplements fed to sheep on a basal diet low in protein were more effective than casein supplements in promoting nitrogen retention and growth.2. The herring-meal supplements caused less extensive formation of ammonia in the rumen than did the casein supplements. This is considered responsible for the differences found in the value of the proteins.3. Meat from the sheep fed herring meal was not tainted in flavour.4. The use of formaldehyde to preserve herring before making them into meal had no deleterious effects when the meal was fed to sheep.

Description: 1. Nitrogen-balance experiments showed that casein supplements fed to hill ewes on a low plane of nutrition in the later stages of pregnancy were used very ineffectively, despite the animals' need for protein.2. In confirmation of McDonald (1948a, b, 1952) extensive conversion of casein to ammonia was found to occur in the rumen, with absorption of ammonia into the blood stream.3. Casein administered to sheep by duodenal fistual was better utilized than when administered by ruminal fistula.4. The course of dissolution in the rumen of casein in the form of tough lumps was observed by a staining procedure.5. It was found possible to process casein in a way that led to better utilization as shown by nitrogenbalance experiments. This processed casein gave less ammonia in the rumen.6. It is concluded that the formation in the rumen of ammonia from proteins may be an important factor determining their usefulness to the animal. Processing may have effects on the value of a protein for ruminants quite different from those on the value for non-ruminants. The tendency to value proteins for ruminants solely in terms of their digestibility is criticized, and it is suggested that casein has disadvantages as a ‘standard protein’ in nutrition experiments with ruminants.

Description: A total of fifty buffaloes, thirty-five Shorthorn and Shorthorn grades and twenty-nine Egyptian (Baladi) cows of different ages were used to study the thermal reaction mechanism by exposing the animals to direct solar radiation followed by shade. The thickness of the skin was also measured in all animals as it is one of the main factors in heat regulation. The results were as follows:1. There were species and breed differences in the thermal reactions. Buffaloes were more hyperthermic when exposed to direct solar radiation than either Shorthorn or Egyptian cattle. The Shorthorns were more affected by ambient heat than Egyptian cattle.2. The skin thickness of the buffalo was double that of the cattle. In all animals the thickness of the skin increased with age.3. It is suggested that the adaptability of farm animals to tropical and subtropical zones is better assessed under shade and under normal husbandry conditions than by exposing them to direct sunlight.

Description: 1. Certain characteristics of bull semen have been examined at four artificial insemination centres in England. One hundred and twenty-one samples of semen, comprising 168 ejaculates from seventysix bulls of seven breeds, were examined. The semen from 119 tested samples was subsequently used to inseminate 4604 cows.The following semen characteristics were studied: volume of ejaculate; concentration of spermatozoa; incidence of dead spermatozoa; incidence of morphologically abnormal spermatozoa; initial fructose concentration; resistance of spermatozoa to temporature shock; methylene-blue reduction; O2 uptake; fructose utilization; visual evaluation of motility; impedance change frequency; and fertilizing capacity (conception rate).A clinical examination was made of the reproductive organs of each bull.2. Variations in the concentration of living spermatozoa and in the incidence of dead spermatozoa were found to account for most of the variations in the metabolic activity of semon: they also largely explained differences in physical activity as assessed by visual estimation of motility or by impedance change frequency.3. Although the rates of methylene-blue reduction, O2 uptake and fructolysis showed a close correlation with the numbers of living spermatozoa present, O2 uptake and fructolysis per living cell decreased with increasing cell concentration.4. Variations in metabolic activity showed no correlation with variations in the morphological characteristics of the spermatozoa, except in the case of spermatozoa with bent tails. These forms occurred in some samples as a result of staining treatment, but their incidence was positively correlated with the O2 uptake and fructolysis per living cell.5. There was evidence that highly active spermatozoa are more resistant to temperature shock than less active spermatozoa.

Description: 1. The solubility of phytate in the presence of protein has been determined over a pH range 6·5 to 0·5.2. The fall in solubility of phytate in the region of pH 2·5 is shown to be due to a reaction with protein.3. The reaction could be reduced considerably by adding calcium.4. The mechanisms of these reactions are discussed.

Description: Short columns of air-dry soil crumbs were wetted at different rates and, after draining to a standard suction, the amount of water taken up by each column determined. It was found that this in the other under continuous grass. The extrapolated value of the cohesion of the grassland crumbs at zero rate of wetting was twice that of the arable, indicating an additional cohesive force in the grassland crumbs. The cohesion of the arable soil fell much more rapidly with increased rate of wetting than that of the grassland, probably because the roots in the grassland crumbs provide easy escape passages for the air.The increase, with rate of wetting, of the amount of water held by a soil sample against a given suction is important, at least up to 200 cm. of water. This dependence of the pF curve on rate of wetting is of particular significance for laboratory studies of water movement in soils.

Description: 1. An analysis has been made of the production records of over 1400 heifers got by A.I. bulls at five non-Board centres. The A.I. heifers, when compared with other heifers in the same herd in the same year, showed no significant increase in yield but a significant increase in fat content.2. The difference in yield between A.I. and contemporary non A.I. heifers was not significantly different in herds at all levels of production. This would suggest that only a small proportion of the differences in yield between the herds in the sample was genetic in origin. In fat percentage, there was some evidence, though not very conclusive, that rather more of the inter-herd variation was genetic.3. Significant differences were found between the progeny groups by different sires in both milk yield and fat content. The standard deviation of the variation due to the breeding value of the sire was 37 gal. and 0·13% fat respectively.4. Methods of interpreting progeny tests made under A.I. conditions are discussed theoretically. It is concluded that the comparison with heifer contemporaries in the same herd is most satisfactory for milk yield and the simple average is best for fat content.5. The relevance of these results to the genetic structure of breeds is discussed. They are in good agreement with the conclusions from pedigree analysis that the genetic differences between the dominant group of herds and the mass of commercial cattle in each breed is not great.

Description: A short account is given of 7 years' breeding for high and low brooder-house viability in a White Wyandotte flock, in which mortality, to 8 weeks of age in most years, varied from almost 50% in the early years to 10% in the last year (1947). When separate sections of the flock were established, the lowviability section showed consistently greater rearing losses than the high-viability section.Brooder house viability appeared to have a relatively low additive heritability, when estimated from such of the records as were suitable, the pooled estimate from differences amongst sires' progenies being only about 0·07. There was definite evidence that mortality was affected by the common maternal origin of full sibs, the heritability estimated from differences amongst full-sib progenies of dams mated to the same sire being significantly higher than that estimated from differences amongst the half-sib progenies of the sires.

Description: In order to form a basis for any improvements of cattle and pasture management in East Africa it was decided to observe the grazing habits of the local cattle. A review of the literature shows that animals' habits can be influenced by temperature, but no record could be found to indicate the effect on the animals of elevation and an equable climate.A summary is given of the results obtained during 720 cow-watching hours. Comparing these results with those obtained by other workers it is clear that Bos indicus cattle on a high-level plateau under tropical conditions have distinct and unique habits. On the average, during days with 12 hr. daylight 7·7 hr. were spent in grazing, 93% of this time being during daylight; 5·2 hr. were spent in ruminating, only 23% of this being during the hours of daylight.

Description: Between 1946 and 1950 multifactorial field experiments were carried out to determine the potentialities and effectiveness of chlorinated phenoxyacetic acids for the selective control of weeds in linseed (oil flax). The initial experiments of 1946 demonstrated that treatment with sodium 2-methyl-4-chlorophenoxyacetate led to considerable increases in the yield of seed through a reduction of the weed population and the consequent decrease in weed competition.The subsequent experiments were undertaken on relatively weed-free crops so that the direct effects on the crop of compound, formulation, and stage of growth at the time of application could be investigated along with differences in varietal response. Amongst the observations made were time of flowering, straw length, the yield of seed, capsule production, seeds per capsule and the weight, oil content, protein content and germination capacity of the seed.At similar dosages sodium methylchlorophenoxyacetate is less phytotoxic than sodium 2, 4-dichlorophenoxyacetate while the parent acid and particularly the ethyl ester of the dichloro - compound are much more injurious. With sodium methylchlorophenoxyacetate the tolerance is greatest between the post-cotyledon stage and a height of 20–25 cm.; within this range of plant development dosages up to 3·5 lb./acre have no adverse effects on the yield of seed. Treatment within 2–3 weeks of flowering delays flowering and reduces the seed weight. When dichloro-compounds are employed there are additional effects, such as the formation of abortive capsules or a reduction in the number of seeds per capsule. Under some conditions the oil content and the germination capacity of the seed is depressed but the protein content is increased.

Description: Detailed investigations on identification and classification of lucerne varieties and strains were conducted at Cambridge for four years, 1949–52, on lucerne sown in row plots and on twelve typical varieties planted out in replicated trials as single spaced plants, using 200 plants of each variety. A number of physiological and morphological characters were examined and the resulting data was analysed statistically.The characteristics used for classification are those which showed considerable variation between varieties, but at the same time these differences were maintained consistently from year to year. They proved to be unaffected by a different way of growing the plants or by small differences in soil fertility or season. The results are shown in Tables 1–17, and three basic classifications with distinguishing features of types and varieties are given. The correlations established between various characters on twelve varieties are given under the heading ‘Correlations’ at the end of the results.(a) The first classification into early, mid-season, late and extra-late types, based on the time of flowering, spring and autumn growth, gives a fair indication to the growers regarding earliness and productivity of various varieties.(b) The behaviour of certain varieties from South America, and in particular Saladina, an Argentine variety, which is vigorous and productive under native country conditions but has lost this ability under Cambridge conditions, indicates plainly that classification based on these three characters can be applied only to the country under whose conditions it was established. Therefore any variety especially obtained from a country of extremely different environmental conditions and management system should be checked in these respects even if a description is given.

Description: 1. Examination of the composition of hay grown in the east of Scotland during the 4-year period 1948–51 has confirmed earlier work indicating the low protein content of this material. In addition, the digestibility of the protein was found to be low, particularly in the case of the seeds-hays, most of which contained insufficient digestible protein to balance the starch equivalent in meeting the maintenance requirements of cattle.2. In nutritive value the seeds -hays were markedly inferior to samples from England and Wales examined by other workers, but very similar to mature ryegrass hay grown in Northern Ireland. The meadow hays examined were of similar starch equivalent but somewhat richer in protein, and this was associated with a higher digestibility of the protein; in consequence the ratio between digestible protein and starch equivalent was more nearly balanced for the maintenance feeding of cattle.3. Applications of sodium nitrate or ‘Nitrochalk’ about 10–20 days before mowing produced very variable responses in the unusually dry season of 1949, but in other years significant increases in protein content were almost invariably obtained. Low protein seeds-hays of the type commonly found in the Lothians were more responsive to this fertilizer treatment than timothy meadow hay, and while increases in protein content of 20–30% were commonly obtained, when relatively heavy dressings of fertilizer (3 cwt. or more per acre) were used, increases in the region of 50% were sometimes recorded. In most years treatment about 10 days before mowing was fully effective in improving the protein content of the hay. Earlier treatment may be preferable in a very dry season, but in more normal years this may increase the yield of the hay and so diminish the effect on protein percentage.

Description: 1. A study has been made of the cause of urine burn in pasture.2. It has been shown that urine burn could occur under dry soil conditions due to the osmotic pressure effects of the urine.3. All seeds present in the urine-affected soil are killed.4. An inhibitor of root growth, to which clover roots are especially sensitive, is present in the urine of cows and sheep.5. This inhibitor, which is not heteroauxin, is acid in character and is destroyed in soil in a few days.6. It is suggested that the inhibitor is an inhibitor-auxin complex, of which the auxin portion might be heteroauxin. The possibility that the inhibitor is an auxin precursor is discussed.7. It is contended that the reduction of clover growth relative to grass growth in a urine patch is not simply the result of shading due to increased grass growth.8. The root inhibitor, the temporarily high pH, the presence of free ammonia, and the high concentration of ammonium ions may be important factors in the reduction of clover growth.

Description: 1. Thirty-one buffalo-cows of different ages were tested for the symptoms and duration of oestrus, and the incidence of post-partum oestrus and conception. Clinical examinations of the vagina were also carried out.2. The symptoms of heat were less intense than in cattle and there was no homosexual activity.3. Pro-oestrus occurred in 43% of the cases with an average duration of 21.20 hr. whilst metoestrus occurred in 67% of the cases with an average duration of 19.20 hr. The average duration of oestrus was 28.47 hr.4. The onset and cessation of oestrus were either abrupt or gradual. The phenomenon ‘split oestrus’ was observed intervening normal cycles. This was not characteristic of the individuals.5. The average interval to post-partum oestrus was 43.80 days. The average number of silent heats per individual was 0.86. Conception took place after an average of 1.71 services whilst the breeding efficiency was 93% in the calving buffaloes.6. Normal clinical changes in the vagina (temperature; nature and amount of secretion; picture of smear) were not reliable indicators of oestrus.7. Further problems concerning reproduction in the buffalo are suggested.

Description: 1. The amounts of amino sugar-N present in acid hydrolysates of six soils with nitrogen contents ranging from 0·17 to 2·82% have been estimated by colorimetric and alkaline decomposition methods.2. Recovery of amino sugar-N after hydrolysis of chitin or glucosamine was found to be unaffected by the presence of soil during hydrolysis.3. Substances known to interfere with the methods of amino sugar analysis employed were not detectable in the soil hydrolysates.4. From the amounts of amino sugar-N liberated by acid hydrolysis it is deduced that 5·10% of the total-nitrogen of the soils examined was in the form of amino sugars.5. The decomposition of amino sugars in soil has been studied by comparing the rates of decomposition of chitin, glucosamine, casein and yeast nucleic acid when incubated with soil under conditions found to produce rapid nitrification of ammonium sulphate.6. Glucosamine and chitin are readily decomposed by soil micro-organisms but not so rapidly as casein or yeast nucleic acid.

Description: 1. Two sample cockerels from each plane of nutrition treatment were killed and dissected at 0, 4, 10, 15 and 24 weeks of age. Details of the dissection technique are given.2. All organs and tissues were weighed both wet and oven-dried. The total dry-matter content of the birds increased from 21% at hatching to 32% at 24 weeks.3. The chief age changes in the proportions of the major joints of the bird consist of a marked increase in relative mass of wing, and a lesser increase in the leg joints. The early maturing head and neck joints decrease in relative mass by approximately onehalf. There are no treatment differences in the gross proportions of the birds calculated on the basis of weights of the major joints.4. The advantages and disadvantages of the various methods of presenting quantitative growth analysis data are discussed. Reasons are given for employing several different methods in this work.5. The amount of fat in the carcasses analysed varies considerably between individual birds. There are no consistent age or treatment effects on the fat contents of the cockerels. The interpretation of McMeekan's dissection analysis data is discussed, and reasons are advanced for conducting future experiments of similar nature on the basis of a fatfree carcass. It is argued that adipose deposits should not be considered in the same category as body organs and tissues.

Description: 1. Ten local Zebu cows representative of Africanowned cattle in Central Tanganyika, maintained under good African husbandry conditions, were temperatured twice daily over a period of 134 days from 23 July to 3 December, whilst the general meteorological environment was recorded.2. The period of observations was divided into four parts, during two of which differential planes of nutrition were maintained between two groups of animals, the first and last parts being control periods when the plane of nutrition was common to all animals.3. The diurnal variation in rectal temperature wasapproximately 99·0–102·5° F., arange of 3·5° F., whilst the atmospheric shade temperature varied about 12° F., from 64 to 76° F. at commencement of observations, and from 71 to 83° F. at the warmest period of the observations.4. The variation within morning rectal temperatures was greater than that within afternoon rectal temperatures.5. The low rectal temperatures in the mornings reflected inadequate nutritional level to maintain body temperature, as they were significantly increased by a moderate supplementary ration.6. Supplementary feeding did not affect the afternoon temperatures.7. Daily mean rectal temperature of the cows in the morning was verysignificantly negatively correlated with atmospheric temperature.8. Rectal temperatures of ten cows' temperatures at 2 hr. intervals from 07.00 to 21.00 hr., over a period of 7 days, was positively correlated with direct sun temperatures taken 4 hr. before rectal temperatures.9. Rectal temperatures were positively correlated with the dew-point in the morning, but were unrelated with the lower dew-point in the afternoon.10. It is suggested that afternoon temperaturing of experimental animals of local Zebu type under African husbandry conditions might be more informative for clinical purposes than the customary morning temperaturing, owing to the lower variation.11. It is tentatively suggested that the thermoregulatory system of local Zebu cattle may be regarded as operating a micro-adjustment mechanism to compensate for immediate variations in micro-climate, superimposed on a macroadjustment mechanism to extend the limits of operation of the micro-adjustment in accordance with seasonal trends of the macro-climate.12. Further data are being collected to clarify these tentative conclusions.

Description: The investigation shows that when water-logged soils were treated with nitrogenous manures and fertilizers like oil cake, water hyacinth, ammonium sulphate and sodium nitrate, a large volume of nitrogen evolved as gas. This loss began 7–12 days after application of different treatments and was quicker from inorganic fertilizers than from organic manures. Besides loss as gas, a large amount of nitrogen was also lost in the drainage. The results suggest that if fertilizers like ammonium sulphate and sodium nitrate are applied to rice-fields by top dressing during the active vegetative growth of the crop, the loss nitrogen as gas will probably be greatly minimized.

Description: 1. During the period May 1948 to May 1952, a study was made of the influence of seasonal fluctuations in the nutritive value of the natural pastures in the Bankenveld region of the Transvaal, on the growth, reproduction and production of cattle. The paired method of investigation was adopted, each heifer maintained on grazing alone having a related counterpart of the same age which received supplementary feeding during the winter months. The former treatment was termed ‘Low plane’, and the latter referred to as the ‘High plane’. Four breeds were included in the investigation, viz. Friesians and Jerseys, and Shorthorns and Afrikaners, thus representative of both dairy and beef types. The latter breed also represented the stock indigenous to South Africa. Initially five pairs per breed were studied, but deaths and other causes depleted the numbers to twenty-eight head after 4 years of investigation.2. Since the investigation formed part of a series of studies which have been in progress at the University of Pretoria and Agricultural Research Institute during the past two decades, the results of which hitherto remained unpublished, a review is provided in the early chapters. To furnish some indication of the natural conditions ruling in the Bankenveld region, the agro-ecological background is discussed, particular attention being paid to physical and nutritional factors. It is shown that for at least 6 months of the year the climate tends to be subtropical, whilst the results of digestion trials on pasture samples, indicated serious nutritional depressions in the natural grazing during winter.

Description: Investigations have been carried out in this department in recent years with the object of establishing the minimum protein requirements of the bacon pig. The results were recently summarized in this Journal (Woodman & Evans, 1948). The minimum protein standards recorded in that communication are consistent with the attainment of the maximum rate of growth compatible with the net energy content of the diet. The basal foods employed consisted throughout of 2 parts of barley meal and 1 part of middlings (fine bran), together with a little lucerne meal and minerals. Briefly, it was found that such a diet, when supplemented with 7% of white-fish meal, supplied the minimum amount of digestible protein required for the quickest possible rate of growth between weaning and 90 lb. live weight, when the level of feeding was such as is shown in the feeding chart (see Table 7). It was also found unnecessary to include any protein concentrate in the diet beyond 90 lb. live weight to ensure the maximum rate of growth over this later period. The requirements were based on the results of statistically designed growth trials, and were confirmed by nitrogen-balance determinations carried out in metabolism crates. It was found that nitrogen retention was just as favourable on the basal diet supplemented with 7% of white-fish meal as when the protein level was increased by feeding higher amounts offish meal.

Description: 1. A method of perfusing the skin of the flanks and the backs of Ayrshire calves and embryos with indian ink is described.2. The distribution of blood vessels in the perfused skins has been studied.3. Three plexuses of blood vessels have been observed in the skins. The first lies below the corium; the second is at a level between that of the ‘sweat glands’ and the sebaceous glands; and the third extends from beneath the epidermis to above the second plexus and is a deep network of many fine blood vessels.4. The presence of venae comites in the skin is discussed.5. The ‘sweat glands’ appear to have a very poor blood supply, while the hair follicles and papillae are richly supplied.6. Both the ‘sweat glands’ and the hair follicles are supplied with blood from the second plexus.7. The vessels of the third plexus appear to enmesh the individual hair follicles at different levels.8. Blood vessels supplying the skin in the back and flanks of the animals originate from the intercostal arteries and so pass through the heat generating intercostal muscles.

Description: Observations were made on four Suffolk lambs from birth to 14 months of age, wool and skin samples being taken periodically. The lambs were on a high nutritional plane and grew well throughout the experiment.1. There is good agreement between estimates of growth based on body weight, calculated surface area, and expansion of tattooed squares.2. Fibre Type Arrays were Valley or Plain.3. Benzene tests showed considerable medullation in the fleeces of all the lambs, mainly in the posterior parts. There were practically none on the shoulder.4. The weight of keratin produced daily per unit area of skin reached or exceeded the figure given as maximal by Galpin (1948) in only six samples, of which four were grown prior to 1 month old.5. The follicle population completes its development early, only a few secondary follicles being added after birth. The definitive S/P ratio is 5/, which is similar to the Leicester, and lower than in the Romney breed. The follicle density, although high at birth, is lower than in the Romney or Leicester, after 9 months old. Both S/P ratio and follicle density are higher than in the Blackface breed.6. The transitory black colour of the birth-coat of Suffolk lambs is due to pigmentation of the tips of many fibres; this may affect any type of fibre from haloes and sickles to histerotrichs. With very few exceptions all follicles cease to produce pigmented fibre at or shortly after birth of the lamb. Large amoebic melanoblasts are present in the skin.

Description: 1. A survey of the trade in fat cattle, calves and sheep through the collecting centres of the Ministry of Food has been made for the counties of Anglesey and Caernarvon.2. The results show that the Anglesey stock are invariably heavier and in better condition and marketed slightly earlier in the year, than those of Caernarvon.3. The imported fat cattle were heavier and more uniform than the home-bred.4. A check has been made of the variations in live-weight of fat cattle according to colour. Invariably the Black cattle (Welsh) have been lighter, and the Red/White (Hereford) heavier than the average live weight of all cattle of both sexes.5. The bulk of the meat produced in the two counties is delivered during the autumn months, confirming the experience that the winter fattening of cattle is not now widely practised.6. In sheep husbandry the two counties are complementary. The small draft mountain ewe, crossed with a heavier type ram, is capable of rearing a fat lamb practically equal to her own body weight in less than 6 months.7. Losses in mature ewes and rams are suspected to be high because of the small proportions of them, in relation to the population figures, that are delivered to the collecting centres.

Description: The follicle population of the Blackface breed (‘double-coated’) was followed in skin samples taken from four lambs at eight intervals between 3 days and 43 weeks of age. The follicle population differs greatly from that of the Romney and Leicester breeds previously studied (Burns, 1949).1. At 1 month old the secondary/primary follicle ratio (S/P) was slightly lower than the Leicester and much lower than the Romney, and the difference became accentuated with age.2. Fewer secondary follicles are developed after birth than in the Leicester or Romney, although the period during which they can be developed is longer, extending at least to 12 and possibly to 17 weeks after birth.3. The follicle density is less than half that of the Leicester, but the difference in S/P ratio is not sufficiently large to account for this, which is mainly due to the Blackface having a much lower density of primary follicles at birth.4. The possibility is suggested that the secondary follicles arise as a result of ‘induction’ by ‘follicle organizer’ coming from primary follicles in a quantity which decreases with advancing age. It may be that when the primary density is high the areas affected by organizer from each primary overlap, providing sufficient organizer to permit of numerous secondary follicles developing at a late post-natal stage, as reported in the Merino.5. The Blackface contrast with the other breeds in that its primary follicles are conspicuously larger than its largest secondary follicles. All primary fibres are medullated except when about to shed, but many secondary fibres are free of medulla. Kemps are produced only by primary follicles, some of which however produce long ‘hair’ fibres.6. Many fibres which grow strongly medullated fibres during summer change to the production of non-medullated fibres in winter. The shedding of the kemps in spring should probably be looked upon as physiologically an autumn moult, since the fibres cease growth and produce ‘brushes’ during the autumn.

Description: Records for milk, fat, solids-not-fat and fat percentage over forty-eight complete lactations were used as uniformity data to determine the relative efficiencies of a variety of experimental designs used in dairy husbandry experiments.In general, it was found that:1. Experiments conducted during the earlier part of the lactation are more efficient than those conducted during the later part.2. Three-weekly periods are generally more efficient than 5-weekly periods.3. If 3-weekly periods are used, then extending the time of the experiment over four such periods instead of three reduces the error. The converse is the case with 5-weekly periods since the experiment is carried over into the highly variable later part of the lactation.4. Grouping the animals according to the yields recorded during the first 40 days of lactation does not appear to reduce the error.An analysis of covariance using the pro-experimental records of the performance of the animals has been carried out on ordinary group trials and it is hoped to publish the results at a later date, but investigations on the data have shown that both reversal and Latin square designs are more efficient than ordinary group trials even when such an analysis is performed.

Description: The weight, length and quality (fineness) of wool produced at different times of the year and under different nutritional conditions has been determined over a period of three years by clipping at monthly intervals the wool grown on delineated skin areas of sheep. The treatments consisted of(a) wet ewes, grazing on pasture all the year, subjected to high and low levels of feeding during the ‘dry’, pregnancy and lactation periods;(b) dry ewes and lambs fed differentially on grazing during the winter and spring;(c) wet ewes fed in stalls on a diet of constant composition at rates sufficient to maintain constant effective body weight (i.e. making allowance for pregnancy increase and fleece weight increase). A small number of these ewes was also subjected to increased environmental temperature during the winter.The experiments have shown the existence of a marked seasonal rhythm in wool growth having a maximum in January (midsummer) and a minimum in July (midwinter). Changes in weight of wool grown are caused by sympathetic changes in both length and diameter. At the same level of feeding the rate of wool growth in midwinter is about onethird of that in midsummer.The nutritional demands of pregnancy reduce the rate of wool growth in winter and those of lactation delay the rise in production in spring. Nutrition also plays an important part in determining the time of the maximum and minimum. In dry sheep the maximum tends to occur before midsummer when pasture growth is at its best, but lactation in wet sheep prevents the expression of a maximum early in the summer, so that in these ewes it generally occurs after weaning, and therefore after midsummer. The level of nutrition also determines within limits the magnitude of the maximum and minimum.The fundamental cause of the seasonal rhythm of wool growth remains obscure. Nutrition, pregnancy and lactation can modify the rhythm, but it exists strongly even when variations due to these are eliminated. The seasonal rhythm of solar radiation has recently been shown to influence rate of wool growth, particularly during winter, and though this is undoubtedly one factor it is not the only one. Temperature has been suggested elsewhere as a possible cause, but the experiments described do not support the theory that environmental temperature has any direct effect on wool growth. It is suggested, however, that the seasonal rhythm of temperature may be a second factor.

Description: The survey shows that objective estimates of the yield of maincrop potatoes can be obtained from small samples carefully selected and dug by hand. Samples taken from about 1000 fields gave estimates of the mean yield of all counties sampled with a standard error due to sampling of less than ± 0·2 ton/acre. The precision of the estimate could have been improved by a better distribution of samples among counties.The results point to underestimation on the part of the official estimates, in each of the 3 years, especially in the case of high yields in particular counties, and in particular years. The discrepancy between the official and the survey yields is of the order of 1¾ tons/acre, after all necessary corrections have been applied to the survey yields.The experience gained in the survey indicates that the method of sampling adopted provides an accurate and reliable method of estimating the yields of potatoes which could supplement, and, possibly, ultimately replace the present official estimates if more accurate estimates are required. A national scheme, properly designed, which would include all the potato-growing areas in due proportion should not be unduly expensive to operate. Estimates so obtained would not only be generally more accurate than those obtained by the present official method, but, perhaps more important, would indicate far more closely the fluctuation in yield from year to year.

Description: 1. Unlike many other mammals, the calf is capable of responding to pituitary injections almost from birth. Age has little effect on the ability of the follicles to develop during a series of a.p.h. injections, the follicular response generally being as good 3 weeks after birth as in calves 6–8 months old.2. Ovulation can occur spontaneously in the a.p.h. treated calf before the end of the first month of post-natal life.3. Ova obtained from such ovulations are capable of fertilization, although the percentage becoming fertilized is very low. This is thought to be due to the infantile state of the Fallopian tube and the difficulty in inseminating into the uterus, rather than faulty maturation of ova.4. Although many follicles (10–60) can develop during a series of a.p.h. injections, superovulation was not consistently obtained either by intravenous injections of a.p.h., l.h. or p.u., or combinations of any of these three.5. Superovulation can generally be obtained, with the formation of many corpora lutea, if the a.p.h. treatment is repeated a second time after a period of luteal activity.6. The inhibitory effect of a corpus luteum on ovulation in cattle can be overridden in tho a.p.h. treated animal if suitable quantities of a.p.h., l.h. or p.u. are intravenously injected when the newly formed follicles are approaching maturity.7. Ovulation in the calf at all ages up to 8 or 9 months of age, either in the presence or absence of luteal tissue, is unaccompanied by oestrus. Oestrus, when occurring during a series of a.p.h. injections, commenced after 90–100 hr. of treatment. In such cases slaughter has always revealed the presence of luteal tissue, indicating that ovulation during a ‘silent heat’ had occurred before the commencement of pituitary treatment.8. Great individual variation exists in the ability of the ovary to respond to pituitary injections. This insensitivity to gonadotropins is not confined to young calves and has been observed in calves 4–6 months of age.

Description: 1. An EEL mains-operated colorimeter has been calibrated to obtain rapid estimates of the concentration of spermatozoa in bull semen.2. A general linear calibration relationship has been calculated giving h, the estimated concentration of spermatozoa per ml. of the original semen, aswhere d is the dilution factor and Pd is the absorptiometer reading.3. Under the circumstances of the experiments described, the accuracy of estimates from the above relation was about 1%, and it is considered that the instrument may be effectively used in semen determinations for artificial insemination and in most cases where a rapid determination is required.4. Attention is drawn to the desirability of using standards and occasional check calibrations, and to the possibility that in routine use results may be slightly less accurate than those given above, which were obtained with laboratory determinations.

Description: 1. The resting heart rate of cocks and hens was measured in varying degrees of heat stress, and during acclimatization to heat.2. When the rectal temperature was below 110°F. (43·3° C), the heart rate varied inversely with the severity of the climate up to an air temperature around 99° F. (37·2° C).3. At air temperatures of 99° F. (37·2° C.) and above the heart rate was nearly constant over a wide range of rectal temperatures below 110° F. (43·3° C). It averaged about 50 beats/min. less than in an equable climate.4. Above 110° F. (43·3° C.) there was an increase of about 30 beats/min./° F. (17 beats/min./° C.) rise in rectal temperature. The rate equalled that found in an equable climate, when the rectal temperature reached 111–112° F. (43·9–44·4° C). Over this zone of body temperature the fowls were often agitated.5. In severe heat stress there was a slight fall in the heart rate on acclimatization, but this was small compared with the effect of climate.6. In severe heat stress the heart rate during the day was slightly higher than that at night.7. The relation of these findings to the mechanism of temperature regulation is discussed.

Description: 1. The extraction of leaf protein from autumn-grown perennial ryegrass is described.2. The composition, chemical analysis and rate of feeding of two mashes compared in the experiment are given. The same basal cereal mixture was used in each ration, with fish meal added to one and leaf protein and minerals to the other.3. Two groups of three birds were kept on each ration. Nine-month-old Brown Leghorn × Light Sussex pullets, in full lay, were used.4. The birds were given a 6 weeks' preliminary period on a uniform ration to accustom them to the experimental conditions and to ascertain their potential egg production.5. In a 10-week feeding trial no difference occurred in the number of eggs or the total weight of eggs laid by the birds fed on either ration.6. A small loss of body weight occurred in the birds in both treatments.7. Egg-quality determinations indicated that the specific gravity of the eggs was not affected by the differential feeding. Yolk height was greater in eggs from birds fed on the ration containing fish meal. This ration also resulted in a higher number of eggs with rough shells and containing a higher content of foreign bodies.8. The eggs from both treatments had low ‘Yolk-colour indices’, showing that the leaf xanthophylls were not present in quantities in the leaf-protein extract.

Description: A uniformity trial on groundnuts has been analysed and the results discussed. Plant number is less variable than yield and less sensitive to shape of plot and of block. For yield, long narrow plots are more efficient than shorter and wider plots, in all shapes and sizes of blocks and in Latin squares. The plots should not be arranged end to end along the contours, but side by side, either singly or in pairs, forming compact blocks.The regression of the plot variance of the mean yield per unit area on size of plot approximately follows a linear logarithmic relationship. A similar relationship holds for plant number. The value of the regression coefficient b′ is low and it has been shown that, as expected, there is considerable gain from the use of small blocks. The efficiencies of various confounded and incomplete block designs relative to designs in larger blocks have been determined for some particular layouts, and values for other layouts, ignoring shape of plots and of blocks, have been obtained by interpolation.The field used for this uniformity trial appears equally variable in all directions.

Description: A simple method to determine the expectation of selected minimum rainfall has been developed on the assumption that monthly or seasonal rainfall is normally distributed over a period of years. Although it is realized that a perfectly normal distribution cannot be obtained, practical experience has shown that the assumption leads to no serious discrepancies and the advantage of simplicity is considerable. A detailed example of its use to forecast the agricultural potentialities of dry lands is given.

Description: 1. A digestibility trial is described using sheep fed on the product remaining after herbage leaf-protein extraction.2. The material gave an analysis of 25.7% dry matter, 16.2% crude protein, 0.26% phosphorus, 1.26% potassium and 1.13% calcium.3. The animals showed no loss in body weight during the feeding period.4. The material was of low palatability, and the sheep consumed a maximum of 2½ lb. of dry matter per head daily.5. The average digestibility coefficient of the dry matter was 52.1% and that of the crude protein 67.6%.6. Nitrogen balance determinations indicated a sufficiency of protein in the feed.7. The material barely supplied sufficient potassium and was inadequate in its supply of phosphorus and calcium.

Description: As part of the overall programme of research directed towards an understanding of fertilizer needs of crop plants in East Africa a study of the nutrition of maize in sand culture has been made.The purpose of the work was to study growth and yield in relation to changes in the proportion and concentration of the major nutrients, nitrogen, phosphorus and potassium, and if possible to relate the results to the field behaviour of the crop in fertilizer trials conducted by another section of this organization. Simultaneously studies of the uptake of nitrogen and phosphorus were also undertaken. These latter are discussed in the second paper of this series.This first paper deals only with growth, yield and nutrient content in relation to the nitrogen phosphorus balance, though the methods now to be described were common to all experiments.

Description: 1. Pregnancy and lactation had no effect on the digestibility of the dry matter and nitrogen-containing constituents of the ration of Cheviot ewes fed at a constant level.2. The water consumption of the pregnant ewe was almost doubled during gestation.3. The digestibility coefficients of dry matter and nitrogen in both pregnant and barren ewes fell considerably from November until the beginning of the following April.4. The average nitrogen content of a normal fullterm Cheviot foetus was approximately 99 g.

Description: 1. Earlier work on the digestibility of Calluna vulgaris has been briefly reviewed.2. Determination of the digestibility of heather has been made by two methods, viz. (a) the conventional procedure involving the use of metabolism crates and (b) the lignin-ratio technique applied to tethered sheep.3. A diet consisting of heather alone, and fed in metabolism crates, proved unsatisfactory as a result of low feed intake. Agreement between duplicate sheep in respect of digestive capacity was also poor.4. Satisfactory feed intakes were attained when heather was admixed at levels of 40 and 70% with hay. At both levels the digestibility of the organic matter was approximately the same, and agreement between sheep was good except for crude protein.5. The lignin-ratio technique applied to tethered sheep gave digestibility coefficients for organic matter which were consistent with those obtained by the conventional method; the values for crude protein were somewhat higher. While the organic matter of 10-year-old heather was digested to about the same extent as that of 4-year-old heather, its crude protein digestibility was rather less.6. The advantages and disadvantages of both methods have been discussed; it has been concluded that the lignin-ratio technique is likely to play a useful part in future work of this kind.7. These preliminary results suggest that heather has a higher nutritive value than earlier work would indicate, and that even the winter foliage may compare favourably with hay of moderate to poor quality.

Description: 1. A semi-lethal gene combination has been found in hexaploid species hybrids involving some strains of Triticum macha, but not in comparable hybrids involving other strains of T. macha. The production of these semi-lethal hybrids can be explained by the interaction of two genes designated as ma and mb.2. The gene ma is carried in some strains of T. macha. The gene mb is carried in the third chromosome set of all other hexaploid species of Triticum, in Aegilops squarrosa and in Aeg. cylindrica.3. The semi-lethal gene combination has been found between species which would otherwise produce fertile hybrids and between species which would otherwise produce sterile hybrids. The semilethal gene combination occurs between species which do not overlap geographically.4. The distribution of the genes ma and mb shows that the gene ma originated in T. macha and that the gene mb originated in Aeg. squarrosa and was introduced from there, during the course of evolution, into the hexaploid species of Triticum (probably excluding T. macha) and into Aeg. cylindrica.5. Meiosis in semi-lethal plants was comparable to meiosis in normal plants. But the semi-lethal plants showed a reduction in fertility, probably as a result of their poor vegetative growth.6. The chromosomes of T. macha and T. vavilovi have been no more structurally differentiated than the chromosomes of the other hexaploid species of Triticum.7. The present study has confirmed that the third chromosome set of the genus Triticum has been phylogenetically derived from Aeg. squarrosa.

Description: 1. Piglets reared in a cold building but in pens provided with electrically warmed or wooden beds weighed considerably more at 8 weeks old than piglets reared in pens with solid concrete floors covered with thin permeable cork-tar bricks. At 3 days and 3 weeks old there were no differences in live weight between the three groups.2. Before weaning at 8 weeks old the piglets reared on concrete floors had very much poorer appetites for solid food than had those from the other two groups.3. Although the blood haemoglobin concentrations of piglets on warmed and wooden floors rose between 3 and 8 weeks of age, the haemoglobin concentrations in the group on concrete floors fell. The differences in concentrations between groups at weaning just failed to be statistically significant at P = 0·05.4. Under the conditions of this experiment the provision of electrically warmed or wooden floors diminished but did not eliminate the incidence of a pathological liver condition in pigs which has been attributed to poor housing conditions.5. The low weaning weights, poor appetites, low haemoglobin concentrations at weaning and the presence of the liver disease in piglets born on concrete floors were probably interdependent, but the mechanism and direction of this interdependence could not be explained from the data collected.

Description: 1. The rectal temperature of piglets was determined (a) at intervals from birth up to 18 days, (b) at the same time daily until the piglets appeared to be fully thermoregulated.2. The rectal temperature of a vigorous piglet during parturition may be as high as 104–105° F.3. During the first few minutes after birth the temperature falls to about 100° F., partly as a result of the lower temperature of the external environment and partly as a result of rapid evaporation of amniotic fluid with which the young pig is covered. The fall in temperature is greater with lighter pigs than with heavier pigs.4. The temperature falls until the young pig finds its way round to the teats and starts to suckle. This struggle and activity of suckling together with the warmth in the sow's nest causes a temporary rise in temperature. During the first rest the temperature falls again to about 100° F., but vigorous pigs have a normal temperature within 12 hr.5. Piglets deprived of milk after 5 hr. and 16 hr. suckling experienced a more or less steady fall in temperature to about 98° F. in 2–3 days, when the pigs were comatose and were killed. In the case of a pig which had suckled for 7–8 days the temperature remained more or less normal for 2 days and then declined to 95° F. during 5–6 days. The length of survival depends largely on the initial weight, i.e. on the reserves accummulated during the suckling period, and possibly on the thickness of the insulating layer of subcutaneous fat.

Description: 1. A feeding trial is described including four groups of cattle fed on grades I, II and III silages and on swedes, straw and oats respectively.2. The live-weight gains made are recorded, together with the rate of dry-matter intake.3. The efficiency of the dry matter of the diets was calculated.4. All three grades of silage produced a significantly greater rate of fattening than swedes plus straw and oats. There was no significant difference between the fattening values of the three grades of silage.5. The dressing percentages found for 100 silagefed and 71 swede-fed cattle are given. The swedefed cattle yielded a greater average dressing percentage.6. It is suggested that the higher dressing percentage found for root-fed cattle as compared with silage-fed cattle can be attributed to the more rapid elimination of dietary water from the body in rootfed cattle.7. An animal behaviour study is described, the time spent by cattle on the four diets, eating, cudding and lying down, being determined.8. Cattle fed on grass silage spent longer on feeding plus cudding than swede-fed cattle.9. An experiment is described designed to determine the effect of the dry-matter percentage of the diet on the dry-matter intake of ruminants.10. The results indicate that when ruminants are subsisting on a diet consisting solely of succulents, the dry-matter intake is depressed when the dry-matter percentage of the diet falls.

Description: Ayrshire Cattle Herd Books for the years 1927, 1946 and 1947 were examined to study the breed structure. Extended pedigrees of a sample of registered females showed that more than half their genes had come from eight herds. Most of the genetic contribution of these herds comes through the bulls they breed.Herds were divided into: breeders' herds (a), breeders' herds (b), multipliers' herds (i), multipliers' herds (ii), and herds registering males only. The function and numerical importance of each group is shown. The position of any one herd in the breed hierarchy is unstable. Changes in the extent of specialization of herd function between 1927 and 1946 are described.The Ayrshire breed structure is discussed in the light of its implications on the effective size (N) of the population and on the selection of bulls for breeding.

Description: A study has been made of the relationships of sterile Friesian bulls manifesting ‘knobbed’ spermatozoa, and the conclusion drawn that the characteristic defect of the acrosome is due to an autosomal sexlimited recessive gene (kn).

Description: 1. Chromosome pairing has been studied in twenty-two different sterile F1 hybrids involving the genera Aegilops, Agropyron and Triticum, together with their colchicine derived amphidiploids having chromosome numbers of 2n = 42, 56 and 70. Cytological evidence has been correlated with male and female fertility, while chromosome pairing in the parents has been studied in relation to their amphidiploids.2. Some of the sterile F1 hybrids showed little or no pairing, while in others the pairing was appreciable. There was an association of the amount of pairing with the parental combinations used in the production of the hybrids in that the interspecific hybrids were characterized by a relatively high degree of pairing, particularly those with 28 chromosomes, while the intergeneric hybrids either lacked pairing or showed a low incidence.3. In the A1 amphidiploid generation, chromosome pairing was in all cases high, and in some cases almost complete. In all cases multivalent formation in the amphidiploid was lower than bivalent formation in its undoubted F1 hybrid. Different amphidiploids showed various degrees of differential affinity. Univalent formation occurred in some amphidiploids, while bivalent formation in some was increased by a loss of chromosomes.4. In all cases there was a reduction in chiasmata per nucleus and chiasmata per bivalent in the amphidiploid compared with its parent species. Reduction values were not directly associated with any increase in chromosome number of the amphidiploid, nor with the presence of multivalents.5. No confirmation could be obtained of the view that multivalent formation in amphidiploids is a more generally sensitive index of chromosome homology than bivalent formation in the undoubted F1 hybrid. The absence of multivalents in an amphidiploid does not disprove the existence of structural chromosome homologies between the two parents.

Description: Six Romney Marsh ewes exposed daily in a hot-room to temperatures averaging 105° F. dry bulb and 87° F. wet bulb for 2 months prior to the start of the breeding season all experienced oestrus and, as a group, at the same time of year as non-heated controls.However, when maintained under daily hot-room treatment throughout the pregnancy period only one ewe lambed, suggesting an adverse effect of high temperature on gestation.In a further experiment to confirm this, eight control ewes all lambed, average birth weight of lambs being 9 lb. 5 oz. Of six experimental ewes exposed to temperatures of 107° F. (dry bulb) and 92° F. (wet bulb) for 7 hr. daily during the last third of pregnancy, one failed to lamb and the lambs averaged 7 lb. 15 oz. A further six experimental ewes exposed to similar room conditions for the last two-thirds of pregnancy produced still smaller lambs, averaging 6 lb. 11 oz. at birth, and three ewes failed to lamb.The yield of lamb per ewe was 9 lb. 5 oz. for controls, 7 lb. 13 oz. and 4 lb. 1 oz. for ewes exposed to heat during the final third and two-thirds of pregnancy respectively and, in the previous year's experiment, 1 lb. 2 oz. for those exposed throughout the pre-mating, mating and post-mating period.It is concluded that although high temperature is apparently without effect on the incidence of oestrus in sheep, it is inimical to satisfactory gestation.

Description: 1. A report is given of an experiment to investigate the extent of genotype-environment interaction in the growth rate and reproductive phenomena of certain strains of mice when kept in two food and two temperature environments. Evidence of interaction was found in both characters.2. The results are considered to be of sufficient interest to justify further work along these lines.This might either take the form of extensive studies involving many strains and environments chosen more or less at random, or in more limited investigations where the genotypes and environments are especially chosen because of marked differences.

Description: 1. Observations made on growing a series of crops in rotation over a range of static ground water-levels in a Fen peat soil are recorded.2. The crops used show differences in their reaction to ground water conditions, and the seasonal incidence of rain has an overriding influence on their performance.3. The effects of ground water-level may operate directly on the growth and development of a crop or may influence it indirectly through factors such as weed infestation, difficulties of cultivation, or the incidence of disease.

Description: After it had become evident that vitamin B12 can be considered as a part of the so-called ‘Animal Protein Factor’, several experiments with young fattening pigs have been carried out in the Netherlands. The purpose of these experiments was to gain experience as to the value of products rich in vitamin B12 for pig feeding. In these trials 312 animals were used.The results can be summarized as follows:1. Substitution to a large extent of animal protein by vegetable protein in rations containing tho same total percentage of protein resulted in a retardation of growth.2. Addition of vitamin B12 supplements to feed mixtures low in animal protein in this series of experiments generally gave better results than could be obtained without this addition. In the majority of cases, however, the results did not equal those of the groups which received rations containing the usual amount of animal protein.3. Vitamin B12 can be considered as a component of the animal protein factor, but besides this there probably exist other factors which contribute to the special value of animal protein for young pigs.4. In circumstances such as prevail in the Netherlands, little benefit can be derived for pig fattening from the use of products rich in vitamin B12.

Description: 1. The partition of riboflavin into free vitamin, flavinmononucleotide and flavin-adenine-dinucleotide in the livers and magnums of laying hens fed a diet rich in riboflavin has been determined.2. Free riboflavin in the liver amounted to 4·3% of the total vitamin, and it is concluded that this tissue does not play any part in the day-to-day metabolism of riboflavin secretion in the albumen.3. The average amount of free riboflavin in the magnum is 45% of the total vitamin. As an egg passes through the organ, the amount decreases; this decrease is equal to the amount secreted in the albumen of the egg.4. It is suggested that riboflavin accumulates in the blood while an egg is in the magnum, and in the magnum in the intervals between the passage of eggs, and that the riboflavin in the albumen is secreted at the same time as the albumen.

Description: The composition and weight of young cotton leaves at a fixed age are given for 3 years which had different rainfall before the sowing of the cotton, and for which the final yields of the cotton are also known. These yields are inversely related to the early growth and percentage composition of the crop. It is not possible to explain this, but the differences in early growth and nutrient absorption are in accord with expectation. In a year of heavy rainfall before sowing, surface soil nitrates are low, which accords with the smaller amounts of nitrogen taken up by the plants. Furthermore, there is evidence to suggest that in such a year the physical condition of the soil would be poor, which is consistent with poor growth and the low uptake of nutrients other than nitrogen.In the Sudan Gezira the yields of irrigated cotton are positively correlated with the amount of rainfall in the 6 weeks before sowing. This is not due to increased nitrate in the top foot of soil nor is it due to increased efficiency of absorption of nutrients in years of high rainfall.

Description: The partition of carotenoids and vitamin A in the colostrum of nine cows and six goats and in the milk of three cows and two goats was determined using chromatographic and spectrophotometric methods. The following were the main results:1. The content of β-carotene and vitamin A in the colostrum decreased rapidly during the first nine milkings in both the cow and the goat. The rates of decline were logarithmic. Logarithmic regressions also showed that the decreases in β-carotene were more rapid than those of vitamin A.2. The heifers secreted more vitamin A in their colostral fat than did cows on the same ration. The vitamin A content of the colostral fat of goats was greater during the first lactation than in later lactations. There was no difference in the rates of decrease of the vitamin A content of heifer and cow colostrum, but the difference between the rates of decreases of colostral vitamin A of first and later lactation goats was significant.3. The colostral fat of cows at pasture contained more vitamin A than that of cows on winter rations. There was no difference between the logarithmic rates of decrease in the two groups during the first nine milkings. The colostral fat of four goats receiving winter rations was richer in vitamin A than that of three cows treated similarly, and this superiority of the goat over the cow persisted throughout lactation.4. There was no difference between the carotene content of the colostral fat of the first and later lactation cows. The yield of fat and β-carotene of the heifers was smaller than that of the cows. Cows at pasture secreted more β-carotene in their colostrum than the cows on winter rations. The presence of β-carotene was demonstrated in goat colostrum, although mature goat milk was free from any measurable quantity of carotenoids.

Description: The extent to which early environment affects wool production of Romney sheep was studied by means of measurement of skin growth, and of fibre numbers and dimensions, of lambs reared to 52 weeks on contrasting planes of nutrition.Measurement of skin growth revealed a series of gradients which generally conformed with growth and development principles. A great degree of individuality among animals in skin growth on various regions was expressed, and it was not possible to prove that plane of nutrition caused differential skin growth among regions.An initial low plane of nutrition had a retarding effect on fleece development and fibre growth, but it could not be decided whether there was a permanent effect on fibre numbers. It seems that this is of little practical importance, since a low plane of nutrition during the major part of the follicle development phase does not appear to impair subsequent unit area production, providing immediate nutrition is good.Examination of fibre attributes, and quantitative fibre growth characteristics on various regions of the body, showed a series of orderly gradients. Large differences existed between the body regions for quantitative production per unit area and this suggests a widely differing nutrient supply of various skin regions.The importance of immediate nutrition is emphasized. It appears that permanent effects of early environment on future productivity take the form of a lesser area on which wool is produced. The efficiency of the processes, apparently, is not affected.