ALBERT

Description: SummaryPlasma volume, haematocrit, and haemoglobin concentration were measured in 34 sows. Red cell volume and total blood volume were calculated from plasma volume and haematocrit.The method of back extrapolation of the logarith of Evans blue concentration to zero time possibly overestimated plasma volume. Haematocrit was found to be higher and more variable in the initial blood samples in each experiment, than in the blood samples taken 30 and 60 min later.In animals of the same parity, plasma and red cell volumes were closely related to live weight, but the relationship varied between parities.

Description: Summary1. An experiment consisting of two separate trials was carried out to study the utilization by beef cattle of high concentrate diets containing different amounts of milled barley straw and of protein. For each trial twenty-four Friesian steers, initially weighing about 270 kg, were divided into three groups and the animals within each group then allocated at random to eight dietary treatments. The treatments were based on an all-concentrate diet and three others containing 10, 20 and 30% of milled (1 in screen) barley straw. Four of the treatments consisted of giving the same concentrate mixture with each level of straw, and the other four involved giving concentrate mixtures with increasing levels of protein so that the percentage of protein in the diets was maintained. All the diets were fed ad libitum until slaughter.2. Performance in terms of live-weight gain was considered as the net result of a number of factors, notably the total intake of dry matter, the digestibility of the dry matter, the efficiency of utilization of the end products of fermentation in the rumen and the composition of the live-weight gain. The inclusions of 20 and 30% of straw in the diet were associated with lower rates of gain than on corresponding all-concentrate and 10% straw treatments but the differences obtained did not attain significance. Total intakes of dry matter were greater on treatments containing 10 and 20% of straw than on corresponding all-concentrate treatments, but then declined with further increase in level of straw to 30%. This trend was significantly curvilinear (P 〈 0·01), the equation for the relationship beingY = 5·881 + 0·131X - 0·004X2,with Y being the daily intake of dry matter (kg) and X the percentage of straw in the diet. The maximum intake of dry matter was calculated to occur with a level of 16·4% straw in the diet and represents an increase in total dry matter intake of 18·2% over that on an all-concentrate diet. Food conversion ratio, expressed as total dry matter consumed per kg live-weight gain, tended to increase with increasing proportion of straw in the diet.3. The mean digestibility of organic matter fell sharply with the inclusion of 10% straw in the ration, the decrease being 8·2% where the protein level was not maintained and 9·1% where it was maintained. Further reductions in digestibility occurred on the 20 and 30% straw diets, but the magnitude of the reductions were considerably less than those brought about by the initial introduction of straw into the ration.4. The molar percentage of acetic acid in the steam volatile acids of rumen liquor increased markedly, and that of propionic acid decreased sharply from the all-concentrate to the 10% straw treatment with a similar level of dietary protein. Increase in the level of straw to 30% gave rise to a further increase in the proportion of acetic acid and reduction in that of propionic acid. Analysis of samples taken at 3, 6, 9 and 12 h after feeding showed appreciable differences in pattern between treatments.5. Effects of treatment on killing-out percentage were different for each trial. In trial 1 the inclusion of straw in the diet did not cause any reduction in killing-out percentage, but the maintenance of protein level gave rise to a significantly higher killing-out percentage than was obtained with the lower protein groups. In trial 2 the killing-out percentages showed a significantly linear (P 〈 0·01) decrease with increasing proportion of straw in the ration, and maintenance of protein level did not give any improvement.

Description: SummaryFour perennial ryegrass varieties, S.24, S.321, S.23 and Vertas Hardgrazing, were grown in micro plots containing 30 plants each at a spacing of 5 cm apart. Monocultures and four of the possible six binary mixtures between the varieties were grown in a randomized block design with four replicates. The data recorded comprised dry-matter yields and tiller numbers, and the components of the mixtures were harvested separately. The data were based on both whole plots, to give total production of mixtures and monocultures, and half plots, to give the contribution of mixture components to total mixture production. Four harvests were obtained during 1968, and the data from these were analysed separately and summed to provide the annual total data.Mixtures and monocultures did not differ significantly for annual total dry-matter yield or for dry-matter yield at the separate harvests. However, differences in drymatter yields between monocultures and between mixtures were detected at some harvests. Within mixtures, significant differences between some of the respective components were found at certain harvests, but these were not obtained for the annual total data.The stability of monocultures and mixtures was investigated by a regression technique and considered in the context of the environments used. This technique revealed that there was a specific mixture effect whereby the mixture (S.24 + S.23) differed significantly from all other treatments.Significant differences between monocultures for fertile and sterile tiller numbers were detected. Between mixtures there were differences for fertile tiller numbers, and within mixtures certain of the components differed for fertile, sterile and total tiller numbers.The relationship between dry-matter yield and tiller numbers was investigated by regression analyses over all treatments and for monocultures and mixtures separately. Significant differences between the slopes of the regression lines and zero and between the slopes of the regression lines themselves were obtained.Possible reasons for the differences recorded both between and within monocultures and mixtures are considered and related to the competitive relations existing in the trial.

Description: SUMMARYIn a comparison involving 1467 births significantly more Dorset Horn than Merino ewes lambed during the period 08.00–18.00 h. The distribution of lambing during the day differed significantly between breeds. The daytime patterns averaged over breeds, and differences between breeds in patterns, did not change from year to year. At winter and spring lambings, 37% of Merino and 62% of Dorset Horn ewes lambed during the day (08.00–18.00 h) while during summer the corresponding percentages were 23 and 39.For both breeds, the percentages of primiparous and multiparous ewes lambing during the day period were approximately the same. For Dorset Horns, the proportions of single and multiple births occurring during the day were similar.

Description: SUMMARYStatistical analyses were carried out on the data obtained under very strict conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.The authors have calculated and studied the correlations between faecal and urinary losses of chloride, chloride excretion with the milk, digestible chloride and chloride balance and many other nutritive factors which were analysed for each of the 55 above mentioned experimental diets.The results show that the digestion and utilization of chloride is not influenced by the amount of ingested chloride at the time of the trial. The digestion is generally very high, negatively correlated with dry matter, energy, and pentosans intakes, and positively with nitrogen and potassium intakes. But the most important factor in the fate of dietary chloride seems to be the necessity for the cow to eliminate most of the time high amounts of potassium in the urines.

Description: SUMMARYStudies were carried out on the effect of source, time of lifting and post-harvest treatment of apparently virus-free Arran Pilot seed potatoes on subsequent crop growth. The experiments were carried out in 1961–2 and 1962–3 at Efford, Sutton Bonington and Edinburgh. Seed tubers from the more southern region, which were older and showed greater sprout development at planting, gave plants with a higher stem number at soil level, a higher tuber number and a greater percentage of the tuber yield as seed grade than northern-produced seed. High bulking rates were associated with early emergence, high tuber numbers and late apparent time of tuber initiation. In 1962 southern seed produced plants which initiated tubers early and had low bulking rates and low final yields. In 1963 seed source had little effect on the time of tuber initiation of resulting plants, and southern-produced seed gave plants with high bulking rates and high final yields. Early lifted and greened tubers gave rise to plants with the same pattern of response as seed produced at the southern centre. It is suggested that this variation in response between years was due to the climatic conditions at the time of tuber initiation in the field crop.Seed of a required state at planting can usually be obtained by growth at the centre of ware production provided disease can be controlled and the time between harvesting of seed and planting is longer than about 3 months.

Description: SUMMARYStatistical analyses were carried out on the data obtained under very strict conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.The correlations between faecal and urinary phosphorus losses, phosphorus in milk, digestible phosphorus and phosphorus balance and the other nutritive factors of the 55 above-mentioned experimental diets have been calculated.In dry and lactating cows, with very variable intakes of phosphorus, phosphorus faecal and urinary losses show very wide variations and may be important. They are not influenced by phosphorus intake, and are related, among the many other nutritional factors we analysed only to ingested water and to a lesser extent to the nitrogen of the diet.The phosphorus balance is thus also very much variable and not really related to the composition of the ration.This low influence of the diet on the apparent fate of phosphorus can be explained by the interference of unpredictable but certainly quite variable endogenous phosphorus excretion, which is also probably responsible for the effect we found of individual factors and of the previous nutritional status.In the lactating cows, the phosphorus requirements for milk production influence the utilization of phosphorus since a significant correlation exists between phosphorus secreted in the milk and urinary phosphorus.In our experimental conditions, the Ca: P ratio does not seem to influence the fate of dietary calcium and phosphorus.

Description: SUMMARYEighty-nine lactating sows, which had farrowed at least once before, were given 140 injections with 2000, 1800 or 1500 i.u. pregnant mare serum hormone. Seventy sows served as controls. 124 injections with 2000 i.u. P.M.S. were followed by 113 oestrus reactions and 88 pregnancies, and 16 injections with 1800 or 1500 i.u. by eleven instances of oestrus and six of pregnancy.Oestrus occurred in 69% of the positive reactors on the 5th day after injection, and in the rest either earlier or later. The interval between the P.M.S. injection and the onset of oestrus was similar to that between weaning and oestrus in the controls.The difference between the pregnancy rate of 71% following injection with 2000 i.u. P.M.S. and that of 83% in the control sows from the first oestrus after weaning was found to be statistically highly significant.Mean litter size and weight were not affected by different time intervals between farrowing and P.M.S. injection, nor were there any statistically significant differences in size and weight of litters at birth or at weaning at 8 weeks of age between those of hormonally treated sowsand the controls.The shortening of the farrowing interval by P.M.S. injection had no after-effect on the sizeand weight of litters subsequently obtained with or without hormone application.Injections with 1800 or 1500 i.u. P.M.S. were followed by a reduced pregnancy rate, but the few litters thus obtained were similar in mean size and weight to those obtained with 2000 i.u.or those of the controls.Sows that did not come on heat or become pregnant following P.M.S. injection came into heat at the same times after weaning of their litters as the control sows.The shortening of the farrowing interval by an average of 22 days was considered to be of sufficiently high economic value to warrant the introduction on the farm where the experiment wasconducted of the routine application of 2000 i.u. P.M.S. to all gilts and sows on the 28th day after farrowing.

Description: SUMMARYTwo field experiments have been conducted to investigate the pattern of tillering, ear emergence and survival of the component tillers of three barley varieties, representing old and new varieties. The varieties were grown under contrasting nitrogen fertilizer levels and plant spacings. The results reported are for the variety means and variety x nitrogen and variety x spacing interactions. After the main stem (M) the most frequently occurring tiller was the tiller appearing in the axil of the first true leaf (T2), followed by the coleoptile node tiller (T1) and the tiller in the axil of the second true leaf (T3). The T1 tiller occurred most frequently in the newest variety, Deba Abed, and least in the oldest one, Spratt Archer. Survival rates of the shoots were highest in M, followed by T2, T1 and T3. Higher-order tillers occurred relatively infrequently and had low survival rates. M contributed the largest percentage of the grain yield, followed by T2, T1 and T3. The 13% grain yield advantage of Deba Abed over Spratt Archer was mainly accounted for by the difference in production by the T1 tiller. The results are discussed in. relation to the only other known paper on component tillers in barley.

Description: SUMMARYThe effect of nitrogen fertilizer and irrigation treatments on the leaf-area index (L) and net assimilation rate (E) of a monthly cut sward of Italian ryegrass (Lolium multifolium) is considered.Response to nitrogen was due to increase in both L and E, whereas response to irrigation was largely due to increase in L.The data show little evidence of a seasonal decline in E. This may have been due to the mid-season replacement of old tillers by new, and by the encouragement to new leaf production caused by periodic harvesting.

Description: SUMMARYComplete diets were given ad libitum to dairy cows over a whole lactation in order to study the voluntary intake of food, lactation performance and efficiency of feed conversion. The effect of including four levels 16, 24, 32 and 40 % of coarsely milled barley straw in the loose mix was studied for diets based mainly on barley or on sugar beet pulp, using a double 4 × 4 Latin square design.The results confirmed that cows can perform normally when given complete diets for extended periods. Dry matter and digestible energy intake was depressed at the higher levels of straw inclusion and milk butterfat content at the lowest level. The net efficiency of conversion of metabolizable energy (M.E.) into milk was higher at the higher levels of straw. It is concluded that complete diets for the self-feeding of dairy cows should contain a minimum of about 24 % of coarsely milled straw and that estimated metabolizable energy intake and production were depressed by including straw at higher levels.

Description: SUMMARYEight soil Mn tests, namely, CH3COONH4-, Mg(NO3)2-, H3PO4-, hydroquinone-, 3m-NH4H2PO4-,1·5m-NH4H2PO4- and EDTA-extractable Mn and total Mn were evaluated for their ability to predict Mn uptake by maize (Zea mays L.) on 63 soils of diverse origin. Regression equations were derived by comparing Mn uptake with each test in combination with pH. The best prediction of Mn uptake was provided by a combination of CH3COONH4-extractable Mn and pH; 52·9 % of the variability in Mn uptake was accounted for by these two variables. EDTA and H3PO4-extractable Mn were superior to the other soil Mn tests in predicting Mn uptake.The effect of soil properties on the extractability of soil Mn by each extractant was analysed statistically. Only with hydroquinone-extractable Mn did the soil variables investigated account for a major portion of the variability in the Mn test. The soil variables most often correlated significantly with the Mn test were pH and total Mn. Organic carbon and clay contents were significant only in determining EDTA- and Mg(NO3)2-extractable Mn, respectively.

Description: SUMMARYA method of establishing indwelling catheters in the jugular vein and carotid artery of the pig by way of the blood vessels of the ears is described. The methods used to maintain these catheters patent for long periods are also detailed.

Description: SUMMARYThe incidence of swayback among lambs in two flocks, previously reported, was reanalysed by a specially developed modification of the probit analysis technique in order to allow for the joint complications of an all-or-none trait and a large number of possible classifications for the animals in each flock. The form of analysis described yields predictions of the probability of swayback among lambs for the given circumstances.Breed and sire within breed each affected the probability appreciably even when allowance for live weight of ewe and lamb was made. The effects of live weight, though significant in each flock, were not consistent in direction between the flocks. Other significant factors affecting swayback incidence were the manner of rearing the lambs, week of birth, and, in one flock, the sex of the lamb.

Description: SUMMARYEffects of N as ‘Nitro-chalk’, P as superphosphate, and K as KCl and K2SO4 on ‘available’ P, K and Mg were examined over 14 years. The area was under grass/clover regularly cut 6 times a year.Soil pH was maintained by annual applications of ‘Nitro-chalk’ supplying an average of 4 cwt CaCO3 and 174 lb N per acre. Superphosphate supplying 43 lb P per acre per annum increased available P (modified Morgan method) appreciably even on plots where more than this quantity was taken off in herbage. Applied N also consistently increased available P. It was thought that this was because P in the root system was rapidly mineralized. Applied K consistently reduced available P because of increased uptake in cut herbage, with no apparent increase in root P for mineralization.The amount of available K in soils which received no added K was fairly constant over the period for a given N treatment. About 40 lb/acre/annum of K was released by weathering.There was a very marked interaction effect between rates of N and K fertilizers on available soil K, the large increase in available K where K fertilizer but no N was applied being considerably reduced with increasing N rates. These effects directly reflected uptake of K in cut herbage.Residual values of applied P, K and Mg on the respective ‘available’ nutrients were considerable and persistent.Available Mg was reduced by increasing rates of fertilizer N and by fertilizer K.

Description: SUMMARYThe objective of the investigations reported in this paper was to examine the possibility of using plasma free fatty acid concentrations as a means of estimating food requirements for maintenance purposes in sheep. Estimates derived in these investigations are considered to be less satisfactory than those based on live-weight change. It is concluded, however, that the technique merits further consideration, and that, with more precise knowledge of FFA concentrations in maintenance-fed sheep and of the FFA: food intake response curve, it could provide a useful alternative means of estimating maintenance requirements.

Description: SUMMARYThe digestibility of fats differing in glyceride structure has been investigated, the fats used being natural lard, interesterified lard and beef tallow. Natural lard was found to be better digested than interesterified lard which in turn was better digested than beef tallow, the differences being the result of differences in the digestibility of the saturated fatty acids. The digestibility of palmitic acid was found to be dependent upon its positioning within the glyceride molecule, absorption being greatest when it was esterified in the β-position. The positional distribution of stearic acid was thought not to be the factor limiting the extent of its absorption in the given circumstances. The fats did not differ in their effects upon growth performance or carcass composition and differences in the digestibility of the fats were not reflected in the quality of the carcass backfat. It was demonstrated that increasing the nutrient density of diets through the addition of fat, together with careful regulation of nutrient intake, resulted in improved growth performance and carcass composition.

Description: SUMMARYThe adaptation of the ruminal flora of sheep to the hydrolysis of biuret has been successfully demonstrated. Bi-weekly measurements of biuretolytic activity of ruminal ingesta were made before, during and after the supplementation of biuret to poor, medium and high-quality rations. Generally no activity was found prior to biuret feeding, but an almost immediate response to biuret feeding occurred which increased progressively with the number of days the animals were fed biuret. The time required to reach maximum activity on very low, medium and somewhat higher protein diets were found to be 15, 30 and 70 days approximately. The supplementation with starch in addition to biuret was found to increase biuretolytic activity. Since neither protein nor starch was found to have any direct effect on biuretolytic activity in vitro, a change in numbers of biuretolytic organisms in the ingesta is discussed as a likely mechanism for the adaptation and de-adaptation of the ruminal flora. A stoichiometric conversion of biuret-N to NH3-N by active ingesta was demonstrated in vitro but was not reflected by the nitrogen levels in vivo. The activity of the ingesta was greatly reduced by straining.

Description: SummaryThree experiments were conducted to investigate the influence on nitrogen retention of feeding protein supplements to early weaned lambs direct to the abomasum via the oesophageal groove. In Exp. 1 the lambs received a basal diet of barley and a protein mixture consisting of soyabean meal, sunflower meal and fish meal which was given either in a liquid suspension from a bottle or as dry feed incorporated with the barley. The results showed that the regression coefficients of nitrogen retention on intake were 0.48 and 0.33 with liquid and dry feeding respectively. The regressions of urinary nitrogen on intake were with liquid and dry feeding respectively 0.26 and 0.44.In Exp. 2, various sources of protein were compared isonitrogenously as substitute for part of a barley concentrate ration. The nitrogen intakes and retentions were 14·28 and 5·09, 20·16 and 9·39, 20·53 and 8·19, 19·00 and 7·80, and 18·87 and 7·86 g/day for the control diet and fish meal, yeast, soyabean meal and sunflower meal supplemented diets respectively.In Exp. 3 the fish meal supplement was compared with a high lysine, bloodmeal and with casein as liquid supplements to a basal diet of barley concentrate. The intake and retention of nitrogen were for bloodmeal, casein and fish meal respectively 23·41 and 7·48, 22·56 and 9·11, and 21·88 and 8·31 g/day. It appeared that the protein sources high in methionine resulted in the highest nitrogen retention. The implications of these findings in relation to the nutrition of young ruminants is discussed together with an evaluation of the experimental method as a technique to study postruminal digestion.

Description: SummaryRed clover florets are generally longer than a honey bee's tongue. Original data are submitted showing that honey bees can reach to a depth of 7 mm into the corolla tube of a red clover floret. The importance of this figure is discussed in relation to breeding bees with longer tongues and the breeding of red clover with shorter corolla tubes. Breeding a variety of red clover with more nectar so that honey bees can reach it is considered to be the best solution and would produce an increase in yield of both seed and honey.

Description: SummaryEstimates of endogenous loss of calcium have been obtained from balance studies with growing lambs and adult sheep given diets containing deficient and adequate amounts of calcium and phosphorus. The values were generally lower than those obtained for sheep by methods employing radioactive calcium and it was concluded that the endogenous loss by sheep is considerably less than the figure used by the Agricultural Research Council (1965) and is probably of the same order as that of cattle (16 mg/day kg live weight).

Description: SUMMARYDeterminations were made of the available-water capacities and moisture release characteristics of six soils of different texture from Rothamsted, Woburn and Saxmundham. The amount of available water retained in the surface foot of soil ranged from 1·59 in in a sandy loam to 2·75 in in a silt loam under permanent grass. With one exception soils which had received additions of farmyard manure had significantly higher available-water capacities than unmanured soils.

Description: SUMMARYOf eight experimental fertilizers (with %N; %P2O5; %K2O ratios of 2:1:1) obtained, four contained triple superphosphate and four mono-urea phosphate; all contained muriate of potash. In the first four, urea supplied either 100, 66, 33 or 0% of the total N (ammonium nitrate supplied the remainder); in the second four, urea and ammonium nitrate supplied only the balance of the N, but in the same proportions.For barley, each fertilizer was combine-drilled to give 0·5 or 1·0 cwt N/acre. In 1965, much rain fell after drilling, early growth was not harmed and yields from each fertilizer were the same. In 1966, dry weather followed sowing and all fertilizers checked growth; those containing urea killed many plants and diminished yields. Also, yields from the fertilizers containing urea phosphate were larger than from those containing superphosphate; thus urea phosphate was safer than urea alone. For kale, the fertilizers were broadcast in May to give 1·25 or 2·50 cwt N/acre. None seriously diminished plant number and yields from all were similar.Increasing the proportion of urea in the fertilizers greatly increased %N in the barley grain in 1966, but not in 1965. The crops recovered more N from ammonium nitrate than from urea.

Description: SUMMARYVariety, water and spacing were treatments in two experiments with cotton in 1963 and 1964 in which fruiting points, flowers and bolls were counted and the dry weights and leaf areas of plants were measured at intervals during the season.Until leaf-area index, L, started to decrease, the equation described how dry weight, W, changed. The equation gave smoothed estimates of crop growth rate, C, which were consistent with estimates of photosynthesis made with de Wit's (1965) model. The relationship between G and L conformed to , derived from Beer's Law, rather than C = aL — bL2 derived from the linear regression of E on L. When L 〉 3 the crop appeared to use most of the available light, so that C approached a maximum. Treatments initially affected dry-matter production through the numbers and types of branches and nodes, which in turn affected the sinks available and thus the proportion of dry matter reinvested in new leaf. This initial period, when growth was simple to describe in conventional terms, was denned as the vegetative phase of growth.The start of the reproductive phase of growth overlapped the vegetative phase. The change from one to the other was completed when the rate of dry weight increase of the bolls, CB, equalled C. This indicated that the sink formed by the bolls had increased sufficiently in size to use all the assimilates available for growth. Sink size increased as the crop flowered and was estimated from the product of the number of bolls and the growth rate of a single boll.When CB equalled C, bolls were shed which prevented the size of the sink to increase beyond the ability of the plant to supply it with assimilates. This agrees with Mason's nutritional theory of boll shedding. Because of the crop's morphology and because age decreased the photosynthesis of the crop, the size of the sink inevitably increased out of phase with the supply of assimilates. The extent to which this was so determined when CB equalled C. It is postulated that environment, genotype and agronomic practice affect yield according to whether they increase or decrease the extent to which the sink size and the supply of assimilates are out of phase.

Description: SUMMARYThe growth of ½ ⅝, and ¾ bred Dorset Horn lambs was examined in Western Uganda. These were produced by mating Dorset Horn rams with East African Blackheaded, ¼ bred Dorset and 1/2 bred Dorset females respectively.The influence of type of birth (single or twin) was maximum at the end of the main 2-month suckling period and progressively decreased to 11 months of age. The influence of maternal age did not decline as lambs grew older. Dorset ewes, ¼ and ½-bred, had superior milking capabilities, as measured by lamb growth at 2 months of age, to indigenous ewes. Lambs, ⅝ and ¾-bred, were 26 % heavier than ½-bred lambs at 2 months of age, and as all three types grew at the same rate from 2 to 11 months, ⅝- and ¾-bred lambs retained this initial advantage.

Description: SUMMARYThe potential digestibility of cellulose is defined as the maximum digestibility obtainable when the conditions and duration of digestion are not limiting factors. Techniques for measuring potential cellulose digestibility were examined and the relationship between potential cellulose digestibility and in vivo cellulose digestibility was explored for a range of grasses.Cellulose digestibility was found to reach a maximum value after 5 days incubation in vitro. No further cellulose was digested when the residues from an initial incubation for 6 days were incubated with a second rumen liquor inoculum. The values measured after a single incubation of 6 days duration were similar to cellulose digestibility coefficients measured by the suspension of ground forage samples in nylon bags in the rumen for 6 days. Plant factors appear to limit further digestion and the residue from prolonged digestion in vitro consisted only of lignified and cutinized tissue. Potential cellulose digestibility measured by either of the above techniques was higher than cellulose digestibility in vivo. The difference varied between forages and when the difference was large, the digestibility of cellulose in faeces was high.It is suggested that measurements of the potential digestibility of cellulose in feed and faeces may be of use in estimating the digestibility of grazed herbage.

Description: SUMMARYThree-hundred and thirty-four female sheep of the Blackface, Cheviot and Welsh Mountain breeds and the crosses among these breeds kept as one flock at pasture were bled in September 1966. Concentrations of Ca, Mg, K, Na and Cl were determined on plasma and P on whole blood. Mean concentrations (mg/100 ml) were: Ca 9·65; P 5·54; Mg 2·02; K 23·2; Na 345; Cl 365; and coefficients of variation (%) 11·1, 18·1, 29·0, 10·5 6·7 and 2·3 respectively.Breed was a highly significant (P 〈 0·01) source of variation for Ca, P, Mg and Cl, but except for Mg, the contribution to the total variance was small (〈 10 %). Average values for cross-bred ewes deviated significantly (P 〈 0–05) from those of pure-bred for Ca and P concentration. Live-weight, within class, had a small but significant effect on Ca and Mg concentration.The concentration of Ca and Mg declined very significantly with age of ewe, there was a similar trend for K, while P showed a slight but steady tendency to increase with age, and Cl showed a more erratic increase.For Ca, barren ewes had a lower concentration (– 0·44 mg/100 ml) than ewes with lambs whilst ewes with single lambs at birth had lower concentrations (– 0·35) than ewes with twins. Other factors with effects too large to be ignored (P 〈 0·1) were the interaction of breed x no. of lambs (K and Cl) and swayback history (Cl).

Description: SUMMARYThe effect of three centres of production, two times of lifting and two post-harvest treatments of apparently virus-free seed tubers on sprout development at planting was studied over two seasons. Sprout length and degree of development were determined mainly by the light and temperature conditions during storage. Under similar storage conditions tubers from the most southern region, lifted early and allowed to sprout from lifting produced longer sprouts than those from the more northerly regions, lifted late and sprouted from midwinter. At planting all tubers had sprouts longer than 2·5 cm. Desprouted tubers from the more southern regions had the highest number of sprouts at planting and tubers 'greened' immediately on lifting had the least.An index of sprout development at planting was defined. The conditions and duration of storage had most influence on the degree of development as measured by this index; sprouts were most developed on tubers sprouted over a long period and on those sprouted in a heated glasshouse. The effects of varying centres of production and times of lifting on sprout development at planting were small compared with those readily produced by varying the storage conditions.

Description: SummaryTwo greenhouse pot experiments were conducted to evaluate labelled concentrated superphosphate (CSP) and labelled dicalcium phosphate (DCP) alone and in mixtures for maize grown on soils low, high and very high in available P. On the low P soil yield of dry forage, total uptake of P and uptake of fertilizer P increased linearly with 0, 20, 40 and 80 ppm of P applied as the various fine and granular sources varying widely in P water solubility. Hence, all of these criteria were highly correlated and suitable for evaluating effectiveness of the P on the low P soil. On the soil high and very high in P, only uptake of fertilizer P, which also increased linearly with rate of application, was suitable for evaluating the sources. Total uptake of fertilizer P decreased with increase in soil P level, but relative differences among granular sources were similar at the three soil P levels. Effectiveness of the P fertilizers decreased markedly with decreasing water solubility of the granular sources on all soils; the same trend was true for the fine sources at high soil P levels.Actual uptake of fertilizer P or percentage recovery of labelled P applied was a better basis for source evaluation at high soil P levels than were calculated A values. There was little advantage in this study of labelling with 32P for P source evaluation at the low soil P level over use of multiple rates of the unlabelled fertilizers. However, labelling was essential at the higher soil P levels.

Description: SummaryAn experiment was carried out in which young beef cattle were given diets containing different levels of coarsely milled (1 in screen) barley straw. The proportions of straw used were 0, 10, 20, 30, 40 and 50 % and the performance of animals on these diets was compared with that of similar animals on an all concentrate diet. Each diet was given ad libitum to six animals. There was a significant linear decline in live-weight gain with increasing straw intake, the rate of decline being 0·62 ± 0·133 kg per week for each 10 % increase in the level of straw in the diet. The dry matter conversion ratio increased linearly with increasing straw intake, the rate of increase being 0·65 ± 0·186 units for each 10 % increase in straw in the diet. Dry matter intake was significantly (P 〈 0·001) affected by the proportion of straw in the diet. Although dry matter intake increased to a maximum at a level of 18·8% straw in the diet there was no significant increase in the intake of digestible organic matter (DOMI). There was a significant (P 〈 0·001) linear decline of 0·19 ± 0·04 kg DOMI with each 10% increase in straw in the diet. There was a significant linear decline in chilled carcase weight to the extent of 5·7 ± 0·096 kg for each 10% increase in straw. The killing-out percentage based on unfasted live weight declined significantly as the percentage of straw in the diet rose from 20 to 30%. However, when the killing-out percentage was calculated on the basis of live weight at slaughter less rumen contents there was no significant difference between treatments.

Description: SUMMARYTwo experiments were carried out to study the effect of the ad libitum feeding of whole-milk substitutes, either warm or cold, and the availability of drinking water, on the level of food intake and live-weight gain of calves. Freshly cut grass or pasture was the sole source of solid feed.In Exp. 1 forty Hereford x Friesian male calves were reared individually indoors in a 2x2x2 factorial design experiment. The treatments were full-cream milk powder υ milk substitute, temperature at which the milk was offered, and drinking water υ no drinking water available to the calves. Fresh grass was cut daily and fed ad libitum to all animals from the sixth day of treatment.In Exp. 2, twelve Hereford x Friesian male calves were reared at pasture on warm or cold full-cream milk during weeks 1–7, and on milk substitute during weeks 8–15.During both experiments calves receiving warm milk drank slightly more than calves receiving cold milk; this difference was significant in Exp. 1 only. There was a tendency for calves receiving cold milk to make higher live-weight gains (0·05 〈 P 〈 0·1) when drinking water was available than when it was not. In Exp. 1, the rates of live-weight gain of calves receiving warm or cold milk substitute with drinking water available were 0·99 and 0·89 kg/head/day, respectively: for calves receiving full-cream milk powder the corresponding rates were 0·86 and 0·80 kg/head/day. When drinking water was not available the rates of gain of calves on warm or cold milk substitute were respectively 0·93 and 0·82 kg/head/day, and on full-cream milk powder, 0·94 and 0·55 kg/head/day.In Exp. 2 the rate of live-weight gain measured during the first 7 weeks, whilst calves were receiving full-cream milk powder, was 0·88 kg/head/day irrespective of the temperature at which the milk was given. During weeks 8–14 milk substitute was given, which resulted in rates of live-weight gain of 1·05 kg/head/day for calves receiving warm milk and 0–92 kg/head/day for calves receiving cold.The rates of gain attained on cold milk are considered adequate for rearing calves intended for an intensive system of production. It is also suggested that the use of cold milk could facilitate a marked decrease in the daily labour requirements associated with the artificial rearing of calves.

Description: SUMMARYField experiments were conducted to study the differential responses of a wheat crop to water stress during different stages of its growth. Evidence was produced to show that both the flowering phase and the stage of grain filling and maturation were more sensitive to drought than the vegetative period of growth. Yield of wheat was not reduced when the crop suffered from cycles of water stress induced during the vegetative period, if the crop received favourable water regimes thereafter. Efficiency of water utilization from different water treatments was assessed. There was no relation between the protein and starch contents of the grain and the type of water treatment.The effects of different water treatments on crop development and on components of yield were studied.

Description: SUMMARYMutton Merino ewes, all of which had lambed in the preceding in-season, were divided into two groups some 30 days after lambing.The ‘light’ group was subjected, over 84 days, to a simulated decrease in daylength, achieved by first adding artificial light to the daylight and then stepping down the light at weekly intervals, from approximately 17 h, on 22 January, to natural daylength (13 ¾ h), on 20 April 1967. The control group was exposed to the normally increasing daylength.Starting on 1 March, the ewes in both groups were ‘teased’ and hand-service commenced on 20 April.The breeding activity (oestrus, ewes lambing, lambs born and twin births) as well as the length of gestation and birth weight appeared to be unaffected by the light.It would appear that the ‘short-day’ photoperiodic theory is not applicable to all breeds of sheep, and it is suggested that in sheep with a long sexual season genetic heterozygosity may be responsible for regulating the breeding season by allowing other environmental stimuli, besides light, to trigger-off sexual activity.

Description: SUMMARYThree gilts and three castrated males weighing 23 kg live weight were given four semi-synthetic diets containing increasing amounts of Ca and P. The Ca and P contents (% dry basis) and Ca:P ratios for the four diets were A, 0·30, 0·38, 1:1·27; B, 0·58, 0·68, 1:1·17; C, 0·94, 1·13, l:l·20; D, 1·16, 1·47, 1:1·27. Each animal was slaughtered at 41 kg live weight and the whole body contents of Ca and P determined. Six pigs were slaughtered at 23 kg live weight and their bodies also analysed for Ca and P contents. Dietary concentration of Ca and P did not influence rate or efficiency of live weight gain nor carcass characteristics. Net retention of Ca and P increased with increasing dietary concentration of these elements. Analyses of isolated femurs suggested that optimal mineralization of the bone was associated with a net retention of 8·2 g Ca/kg live weight gain. The data were used to calculate a value of 32·9 mg/kg live weight/day for the endogenous loss of Ca in pigs of 23–41 kg body weight. The values have been used to compute a mineral requirement of dietary calcium which is in excellent agreement with that derived from estimates in the literature.

Description: SUMMARYInternal and external follicle diameters of both primary and secondary follicles of Texel x Ossimi and Merino x Barki ewes were greater, at birth, than those in either respective parent breed; the density of primary follicles at birth was less in the cross-breds than in the parental breeds, for both crosses. There was a greater increase of follicle diameter with age in the Egyptian breeds, and mean follicle diameters of the crossbreds were intermediate between those of parent breeds at ages of 3–6 months and above.Grading up Ossimi sheep with the Caucasian Merino resulted in progressive decrease of mean internal follicle diameter. The F2, with more merino blood, had a greater frequency of the smallest diameter follicles than had the F1.

Description: In the course of an experiment designed to study the effects of calcium and phosphorus supplementation on the performance of Scottish Blackface hill ewes, with particular reference to the premature loss of permanent incisor teeth (Gunn, 1969), blood samples were taken from 40 ewes on ten occasions per year over a 4-year period. These were drawn equally from a control and three treatment groups. The control group followed the existing pattern of ewe management on the farm in question by utilizing improved pastures in the spring and early summer, and the treatment groups were a calcium dosed group (12 g calcium carbonate) and a phosphorus dosed group (13 g monosodium phosphate), both of which received the same management, and an undosed group run permanently on the hill. Details of the management and feeding are given in a previous paper (Gunn, 1969). It is sufficient to say here that mineral dosing took place three times per week between mid-February and the end of May and no minerals except salt were added to the concentrated ration fed to all groups at the rate of 10 oz (283 g)/head/day from mid-February to early May. Lambing commenced at about the end of the first week in April.

Description: Purified diets prepared from finely ground constituents such as starch, casein, gelatine, cellulose, etc., are not readily acceptable by poultry. This is probably due to their powdery nature, for Coates, Kon & Shepheard (1950) found that chicks grew faster when fed a granulated purified diet than when this was fed unprocessed. Granulation was accomplished by mixing the diet with about a third of its weight of water, pressing the resulting paste through a no. 8 sieve and drying the granules at 40 °C.

Description: SUMMARYThe environmental and genetic control of reproductive growth was studied in S. 170 a variety of Festuca arundinacea Schreb. The variety had induction requirements for short days and low temperatures before inflorescence production could occur, but some genotypes became induced with only short-day treatments. Low temperatures and short days in controlled environment rooms were less effective in bringing about induction than winter conditions in an unheated glasshouse. Only non-additive genetic effects could be shown to be significant in the control of induction requirements. Field studies showed that all inflorescence characters were subject to genetic and genetic x environmental control, and they also indicated that seed weight per inflorescence and seed fertility were most likely to show a response to selection. Diallel analysis under glasshouse conditions showed that the seed fertility and 1000 seed weight of the parental crosses were subject to maternal control, but these effects were not detectable in the next generation. Genetic control of seed fertility and 1000 seed weight in the diallel progeny was mainly additive.

Description: SUMMARYEmpty body weight and body measurements were made on 142 lambs from Border Leicester × Merino and Merino ewes mated to Dorset Horn rams, grazed at three stocking rates and slaughtered at approximately 32·3 kg full body weight (FBW). Carcass composition studies were made on 58 of these lambs. An approximate doubling of growth rate during the first 6 weeks of life occurred between stocking rates for lambs from Merino ewes. A smaller difference was found in lambs from Border Leicester × Merino ewes. Growth rates of lambs from Merinos were significantly lower at all times from birth to slaughter. Stocking rate, breed and sex effects on growth rate resulted in lambs reaching mean weight of 32·3 kg at 80–150 days.A three-way analysis of variance was performed on data for all parameters measured using FBW as a covariate. These parameters were of carcass measurements and composition, and of composition of the internal organs. There were no effects of stocking rate on empty body weight, carcass weight, or any carcass measurements. The weight of dry edible meat was depressed at the high stocking rate due to a higher moisture content. The fresh weight of internal organs was lower at the high stocking rate. A number of sex differences were found. Ewes had lighter carcasses and heavier cannon bones; their edible meat had a higher moisture content and higher ash content than wethers. Eye muscle width was less in ewes than in wethers. Internal organs of ewes had a lower EE % and higher CP % than those of wethers. The only breed type differences were in the weights of internal organs and eye muscle widths at the 9–10th and lOth–llth ribs, and age to slaughter.

Description: SUMMARYTwo experiments with sugar-beet seed crops at Dunholme Field Station Lincolnshire,1955–7, one at Broom's Barn, Suffolk, 1963–4, and two in Bedfordshire 1965–7, compared transplanting with various direct.drilling techniques. The early experiments were made with multigerm varieties and the 1965–7 experiments with genetic monogerm varieties.At Dunholme direct drilling under a barley cover crop controlled virus yellows and yielded more multigerm seed suitable for processing than did transplanting. In later experiments transplanting gave variable yields; pests damaged plots transplanted in autumn and those transplanted in spring were susceptible to drought. Many transplants lodged and ripened late and direct drillings produced seed that germinated better.Direct drilling during July with no cover crop consistently yielded better than undersowing or open drilling in August. To establish a regular, dense stand of plants, which is essential for large yields of seed of good germination was more difficult with than without cover crops. The time the cover crop was removed did not consistently affect yield. Crops sown in summer without cover yield most seed but are most susceptible to disease and are unsuitable for areas with a disease risk.

Description: SUMMARYThe components of yield were studied in a local strain of field beans (Baladi) and two Egyptian varieties (Rebaya 40 and Giza 1). Although no significant differences between varieties were detected in yield per plant, there were differences in components of yield. The Egyptian varieties produced heavier seeds but less pods and seeds than the local strain. The higherpod number in Baladi resulted from a capacity to produce more pods per stem rather than from anability to produce more stems per plant.Correlations between yield and other plant characters and between components of yield were computed. The path-coefficient analysis was employed to partition the correlation coefficients and to compare the relative importance of the primary yield components in predicting yield. Pods per plant showed the highest correlation with yield and selection for high yield can be based on it. Seed weight was negatively associated with pod number and seeds per pod but the r values were too low to be of predictive value. Multiple correlations indicated that 95–98% of the variability in yield was accounted for by the components pod number, seeds per pod and seed weight.

Description: SUMMARYThe competitive ability of two natural populations of Dactylis glomerata, one from Norway and the other from Portugal, was investigated by growing them in monoculture and together in a mixed sward under different temperature and light regimes. At 7 °C and 8 h photoperiod, the performance of the prostrate Norwegian population grown in mixture with the erect Portuguese population was suppressed as compared with its performance in monoculture. However, at 30 °C and 16 h photoperiod, when the growth habits of these two populations were reversed in comparison to those at 7 °C, the dry weight per plant of the erect Norwegian population was significantly greater in the mixed sward than in monoculture. The dry weight per plant of the Portuguese population did not differ significantly in the two types of sward at either temperature. The results are discussed in relation to competition for light.

Description: SUMMARYResults of grain analyses for the content of nitrogen, oil and husk are presented from trials in the F1 and F2 generations of four subject varieties, Condor (Avena sativa), Sierra, Avon and Anita (A. byzantina), nine tester varieties, mainly of north-west European origin and the 36 crosses between them.Yield of grain crude protein per unit area was positively correlated with grain yield, but nitrogen content of the grain, expressed as a percentage of dry matter, was inversely related to grain yield in both trials. Although the highest values for grain nitrogen content were invariably associated with low grain yields, the highest yielders had average or slightly better than average values for nitrogen content.Analysis of straw samples from the F2 trial revealed considerable differences between varieties and crosses in the proportion of the total shoot nitrogen (grain + straw) ultimately found in the grain. The proportion of total shoot nitrogen translocated to the grain was positively correlated with the ratio of grain yield to straw yield. High grain yielders took up more nitrogen per unit area from the soil and translocated relatively more nitrogen to the grain from the vegetative tissues than did varieties with low grain yields.Yields of grain oil were highly positively correlated with yields of grain per unit area but there was no significant regression of oil content on grain yield in either trial. In the F2 trial, oil yield per unit area was positively correlated with oil content of the grain. The variety Avon and its crosses had consistently high oil content.There was no correlation between yielding ability and husk content of the grain, and some of the highest grain yields were associated with low mean husk contents. High husk content of the grain tended to be associated with stiffer straw.The results are discussed in relation to improving grain quality in the breeding of new varieties of oats.

Description: SUMMARYRecords have been analysed from a small herd in which early weaning was practised. Piglets were weaned when average weight was 7–8 kg, at about 30 days old. Decreased feeding of sows, followed by a short period of fasting, was practised at weaning.Mean duration of suckling was 31·5 days and mean interval from weaning to oestrus 6·0 days. 93% of sows conceived to service at the first or second heat period. Mean farrowing interval for all sows was 159·7 days (151·9 days for those holding to the first service). Corresponding annual farrowing frequencies, calculated from these figures, are 2·29 and 2·40.Litter sizes at birth and at weaning were 10·7 and 9·3; corresponding weights of piglets were 1·74 and 7·99 kg. With increase of litter sequence there was a significant decrease of weaning weights; however, there was also an increase in size of litter weaned. Seasonal changes of piglet weight were also found. Early weaning can be considered a useful way to increase production.

Description: SUMMARYThe length of wool grown per day, on closely clipped patches of the skin of two sheep exposed to an ambient temperature of 2 °C for 4 days, was reduced to 30% of normal. For individual fibres, this decrease was directly proportional to their normal growth. Fibre diameter was not affected. Growth in a warm 4-day period succeeding the cold period returned to normal and remained normal thereafter.

Description: SUMMARYThe percentage of the total buds produced that dropped before reaching the mature pod stage was estimated as 86·7% in Baladi, a local strain of field beans, and 93·7% in Giza 1, a variety introduced from Egypt. The drop was appreciable both before and after fertilization. There were indications that both inadequate insect pollination and inter-ovary competition contributed to the reduction of pod yield.Self pollen was detected on the stigma in the bud stage 2–3 days before the flower was open. Estimates of natural cross-fertilization ranged from 35·8 to 42·1%, indicating that self-pollination did not lead to complete self fertilization. Hand manipulation of the flowers increased pod set in most of the cases but the line 1W did not respond to this treatment and proved to be highly autofertile.

Description: SUMMARYExperiments to determine the net availabilities of the metabolizable energy (NAME) of a cereal-based diet and a maize-oil diet for maintenance and lipogenesis and the effect of environmental temperature on the NAME of the cereal-based diet are described. Four 1- to 2-year-old Light Sussex cockerels were used.The relationship between ME intake and energy retention was linear for each diet. The NAME'S of the cereal-based diet given at 22° and 28 °C (70.6 ± 1.83 % and 73.6 ± 3.54%, respectively) were significantly (P 〈 0.05) lower than the NAME of the maize-oil diet (84.1 ± 1.85%). It is concluded that the beneficial effect of maize oil on the efficiency of energy utilization is due to a reduced heat increment rather than a reduction in the basal component of the heat production. The higher efficiency from the maize-oil diet led to an increase in the energy retained as fat.The mean fasting heat production at 28 °C was 15 % lower than at 22 °C (43.2 ± 1.45 and 51.2 ± 1.09 kcal/kg/day, respectively). The NAME of the cereal-based diet was not significantly different when the birds were kept at 22° or 28 °C. The lower metabolic rate at 28 °C was reflected in a lower maintenance requirement and in an increase in the deposition of body fat.

Description: SUMMARYCalcium metabolism in dairy cows has been studied at three periods, namely 2 weeks before and 2 weeks after parturition, and also at peak lactation. Of the four parameters studied—percentage absorption from the diet, endogenous excretion, exchangeable pool size and bone accretion rate—only the last showed significant changes, falling at parturition and rising to pre-calving levels subsequently. There was no increase in the percentage absorption of calcium from the diet after calving but total calcium absorption rose because of increased dietary intake.

Description: SUMMARYYields of maize and cotton given N, and sometimes K but no P, were related to equilibrium values of the monocalcium phosphate potential (½pCa+pH2PO4)eq', at which P is neither lost nor gained by the soil. The responses to phosphate fertilizer were not clearly related to phosphate potentials though small responses at large values of (½pCa+pH2PO4)eq were sometimes explained by very small values of δI/δQ (the rate of change of ½pCa+pH2PO4with change in the amount of P on the soil) or by soil reaction. In only one set of maize experiments, response to P was related to δI/δQ. (½pCa+pH2PO4)0 and (pH2PO4)0', determined without adding P to the solution, were equally useful and both were just as well related to yields without P as (½pCa+pH2PO4)eq' (pH2PO4)0 appeared more useful than the logarithm of the total P concentration measured without added P. It wa not necessary to find the equilibrium phosphate potential, or to measure Ca concentration, but correcting the phosphate concentration for pH (so that only H2PO4-ions were taken into account)was worth while.

Description: SUMMARYNineteen experiments were made between 1964 and 1967 on fields where previous sugar beet crops showed symptoms of magnesium deficiency. None, 2·5 or 5 cwt/acre kieserite or 20 cwt/acre dolomitic limestone were tested in a factorial design with none or 3 cwt/acre agricultural salt (crude sodium chloride), and 0.8 or 1.2 cwt/acre nitrogen as ‘Nitro-Chalk’. Additional plots tested kainit (7 cwt/acre) and a large dressing of potash (2 cwt/acre) as muriate of potash.Kieserite and dolomitic limestone increased sugar yield and the most effective dressing was 5 cwt/acre kieserite, which gave 3·1 cwt/acre more sugar than the crop without magnesium fertilizer. Agricultural salt and the larger dressing of nitrogen were profitable, and neither interacted with magnesium on average; the large dressing of potash also increased yield. The magnesium in the kainit increased yield slightly, but the dressing tested supplied too little to satisfy the crop's requirement of magnesium.Each year in late summer the percentage of plants showing magnesium-deficiency symptoms was recorded, and a sample of twenty-four plants harvested from each of the magnesium treatments and analysed. All the magnesium fertilizers increased the concentration of magnesium in leaves, petioles and roots, and also decreased the number of plants showing deficiency symptoms.The magnesium concentrations in plants grown without magnesium differed widely and were related both to the yield response to magnesium fertilizer and to the percentage of plants with deficiency symptoms. Both relationships showed a similar ‘transition zone’ from deficiency to adequate supply, for leaves this was 0·2–0·4% Mg, for petioles 0·1–0·2 Mg and for roots 0·075–0·125 % Mg in the dry matter.

Description: SUMMARYVarious rates of nitrogen fertilizer were applied in early and late spring to two densities of winter wheat to examine their effects on grain yield and its components. A severe attack of ‘sharp eyespot’ (Rhizoctonia solani) allowed an assessment of the effects of the treatments on the incidence of this disease.The disease level was much higher where nitrogen was applied early and increased with increase in nitrogen up to 120 units applied; it was slightly higher at the higher density. Grain yield was slightly greater where nitrogen was applied late; early application gave more, but smaller, ears. Main shoots produced at least 70% of the grain in the high-density plots but less than 50% at the low density. Tillers appearing after early March contributed little to grain yield at the higher density but substantially at the lower one. Tillers produced after early April died without heading. In general, the chances of survival of a tiller diminished with delay in the time of its appearance, but some early tillers died while later ones survived and produced ears. The chances of survival of later tillers were greater at low density and high rates of nitrogen.

Description: SUMMARYThe utilization of different levels of protein, supplied mainly as soybean meal, was examined by a feeding experiment with sheep. Measurements of the concentrations of N-containing rumen metabolites and of blood urea showed that protein degradation in the rumen and removal of urea by the kidneys were limited when highly increased amounts of protein were ingested.

Description: SUMMARYSuppressed development of edible portion in carcasses from cattle fed hay during the early feeding period (216–340 kg live weight) was followed by compensatory growth during the intermediate (341–409 kg live weight) and final (410–454 kg live weight) periods. However, when silage in the early feeding period was followed by corn concentrate in the intermediate period, no increased ‘edible portion’ development was achieved beyond that produced by continuous silage. The final feeding period (corn concentrate) resulted in a decline in ‘edible portion’ percentage in cattle that previously received concentrate in the intermediate period whereas those that previously received silage remained at about the same percentage.Cattle fed hay during the early period had less (P 〉 0·01) carcass weight, less (P 〉 0·01) fat cover, and more (P 〉 0·01) reticulo-rumen weight than those fed corn silage for the same period, regardless of slaughter weight.In the heavy (409 and 454 kg) slaughter groups, cattle fed silage in the early period had higher (P 〉 0〉05) marbling scores than those fed hay. Feeding silage in the intermediate period resulted in lower colour (P 〉 0·01) and firmness (P 〉 0·01) scores in the longissimus dorsi muscle than feeding concentrate at that time. The dietary regimes used in these studies resulted in widely varying growth rates among treatments with consequential differences in the average age of the animal groups at slaughter. Therefore, the treatment effects observed seem to be easily explicable on the basis of age differences.

Description: SUMMARYAdult Merino wethers were fed for 16 weeks on diets of oat straw mixed with urea and pelleted (A); oat straw pellets, with access to a salt block (B); oat straw pellets, with access to a salt-urea block (C); Phalaris straw mixed with urea and pelleted (D); and Phalaris straw pellets (E). A commercial mineral supplement was given during the first 8 weeks, and a laboratory-prepared complete mineral supplement supplied during the second 8 weeks. During the fifth to eighth weeks (period I), and the thirteenth to sixteenth weeks (period II), digestibility and balance studies were conducted on sheep from each treatment.Digestibilities of organic matter (O.M.) and cellulose were generally increased by the addition of urea, but only in one comparison, between diets A and B, was the difference significant. Urea did not significantly affect water intake in relation to food intake.Urea increased nitrogen (N) intake, faecal and urinary N excretion, and N balance, these effects being more pronounced in period II. All sheep were in negative N status in period I; five of the 12 urea-fed sheep were in positive N status in period II. In diets B and C water intake and urine output were positively related to salt intake, but in no diet was there a significant relation between urinary N excretion and total output of urine.Sulphur balances (excluding wool) were generally positive and did not improve significantly in period II despite higher sulphur intakes. However, a corresponding increase in the intake of phosphorus, from 0·5 g/day to about 2·0 g/day, brought nearly all sheep from negative to positive phosphorus balance. With the urea diets there was a significant, negative relation between urinary N excretion and phosphorus balance.Intakes of sodium, potassium, calcium and magnesium appeared to be sufficient in both periods.It seems likely that the improved response to urea which occurred during the experiment was due to the change in mineral supplementation rather than to adaptation to urea.

Description: SUMMARYAn experiment was done to see if three varieties of wheat (Jufy I, Yeoman and Cappelle) of widely different tillering propensities differed in their response to early spring application of nitrogen; and, concurrently and conjointly, to assess the effects of unproductive tillers on the growth of productive shoots.None of the varieties responded to the higher of two levels of nitrogen. The presence of a large number of unproductive tillers appeared to have only a transitory effect on the growth of productive shoots; the latter were able to grow rapidly after the death of tillers and caught up with productive shoots which had been subjected to much less inter-tiller competition.

Description: SUMMARYThree varieties of Avena byzantina C. Koch., Sierra, Avon and Anita, originating respectively in California, Australia and South Africa, together with the Dutch variety Condor (A. sativa L.) were used as ‘subject’ varieties in crosses with a range of nine tester varieties of mainly north-west European origin. The results of a yield trial of spaced F1 transplants and a drilled F2 trial are presented.In the F1 trial there was marked heterosis for grain yield, the thirty-six crosses yielding, on average, 109 % of the higher yielding parent, with individual cross values ranging from 68 to 139%. Heterosis was more marked in sativa × byzantina crosses than in sativa × sativa crosses and the variety Sierra showed particularly high general combining ability. In the F2 trial, heterosis was considerably reduced and the thirty-six crosses yielded, on average, only 96% of the higher yielding parent. In some F1 crosses, heterosis for grain yield was accompanied by transgression of the higher yielding parent in number of panicles per unit area. The number of grains per panicle was positively correlated with grain yield in the F2 trial but no heterosis was observed for this component. Grain size was negatively correlated with yield in the F2 trial and heterosis for this component was observed in a few crosses in which yield heterosis occurred.Straw height was positively correlated with grain yield in the F1 trial but negatively correlated in the F2 trial. Crosses showing heterosis for yield exceeded the mid-parent but not the taller parent in straw height. The ratio of grain yield to straw yield was higher for the progenies of the byzantina varieties Sierra and Avon than for the progenies of the sativa subject Condor. Grain yield was positively correlated with number of days to 50% panicle emergence in both trials.It is concluded that the A. byzantina varieties Sierra and Avon could, with advantage, be used for hybridization with adapted genotypes of A. sativa, thereby enlarging the gene pool available to oat breeders in north-west Europe.

Description: SummaryStatistical analyses were carried out on the data obtained under strictly controlled conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.The authors have calculated and studied the correlations between faecal and urinary potassium losses, potassium excretion in the milk, digestible potassium and potassium balance, and the 75 other nutritive factors which were analysed for each of the 55 above mentioned experimental diets.The results show that three nutritional factors, potassium, dry-matter and nitrogen intakes, influence the fate of dietary potassium. The apparent digestibility of potassium is hyperbolically related to potassium content of the diet since the true digestibility of potassium is very high, unrelated to potassium intake and rather constant and since about 2·2 g of endogenous potassium are excreted in the faeces per kg of ingested dry matter.The quantities of digestible potassium strongly influence both the potassium urinary outputs and potassium balance. An increase in digestible dry matter enhances too the urinary potassium excretion as well as faecal output and lower potassium balance twice as much.But the most interesting feature in the potassium metabolism is that at any level, ingestion, digestion, excretion, there is a very close correlation between potassium and nitrogen.

Description: SummaryResults are presented from freezing tests on five varieties of winter oats from diverse origins, on their crosses in the F1 and F2 generations and on selected F3 lines from six of the crosses.Analysis of the F1 results indicated that frost resistance was mainly determined by recessive genes, additive in their effect, but in the F2 experiment there was evidence of non-allelic gene interaction. Significant general combining ability (GCA) effects were obtained in both the F1 and F2 experiments but specific combining ability (SCA) effects were significant only in the F2 crosses. The variety Novosadsky II displayed consistently high general combining ability.Tests on F3 lines derived from selected F2 plants revealed considerable transgression for frost resistance in all six crosses studied. The results are discussed in relation to breeding for improved frost resistance in oats.

Description: SummarySixteen field experiments made between 1963 and 1967 on direct-drilled sugar-beet seed crops compared the effects of cultural practices on the yield and quality of seed. Sowing in July gave earlier flowering and ripening than sowing in August and usually increased yields, cluster size and percentage germination. Downy mildew was sometimes more prevalent in late sowings.Seed yields increased as the crop changed colour from green to yellow and percentage germination increased greatly as more clusters contained ‘mealy’ rather than ‘milky’ perisperm. Because of natural shedding and bird damage, seed yields then decreased and losses of 0·6 cwt/acre/day were recorded for early ripening treatments. Cluster size and percentage germination continued to increase while yield was decreasing. Crops ripened a month earlier in 1967, the ‘earliest’ year, than in 1965, the latest year.Crops grown in rows 10 in apart lodged less than those sown 20 in apart, ripened earlier and produced, on average, 3 cwt/acre more seed, which was slightly smaller. In one experiment rows 5 in apart gave similar yields but smaller clusters than rows 10 in apart. Row width had little effect on percentage germination. Increasing the distance between plants in the row gave smaller yields with wider spaced rows, but with narrow rows plants 6 in and 12 in apart yielded more than those 2 in apart. Yields from a plant population of 52,200 plants/acre were 4 cwt/acre greater when plants were 12 in apart in narrow (10 in) rows rather than 6 in apart in wide (20 in) rows. Spacing further apart in narrow rows increased seed size. In wide rows many plants 12 in apart lodged, made secondary growth and produced small, late maturing clusters, of which few germinated.Response to fertilizer nitrogen applied in spring was less, and less was needed for maximum yield on the thin Cotswold soils than on the silty clay loam in Lincolnshire, where it doubled yield in 1966. Phosphate and potash applied in spring had little effect on yield. Usually fertilizers had no effect on cluster size or germination percentages, but 1·6 cwt/acre N given to a late-ripening crop in 1965 decreased seed size and germination.Ramularia leaf spot, which defoliated crops in the Cotswolds, was worst on early sown and closely spaced plants, and was unaffected by fertilizer.

Description: SUMMARYEleven forages of known digestible energy/kg dry matter (Naga & el-Shazly, 1963) were used in in vitro fermentation experiments. Direct determinations of digestible energy (D.E./kg D.M.) using the bomb calorimeter were also included, and the values were corrected for gas losses.In vitro fermentations were interrupted every 12, 8 and 6 h, the medium was renewed and volatile fatty acid (VFA) production and cellulose digestion were estimated. Volatile fatty acid production from legumes was high early in the fermentation periods and became lower in later periods. Non-legumes behaved in an opposite manner.Significant negative correlation coefficients between VFA production and D.E./kg D.M. were found for legumes at later intervals of fermentation, while correlation coefficients for non-legumes lost their significance at later periods of fermentation.Digestible energy/kg dry matter could best be predicted for legumes from the volatile fatty acids produced in the second 12 h fermentation period or from the sum of the VFA produced in second, third and fourth 6 h periods of fermentation.

Description: SummaryAn experiment was carried out in which the performance of cattle given diets containing 20 and 40% of coarsely chopped straw (1–3 in lengths) was compared with that of similar cattle given an all-concentrate diet. Each diet was offered ad libitum and twelve Hereford cross steers and twelve Friesian steers were used in the experiment. The live-weight gains and food conversion ratios were significantly better for the Hereford cross animals but there was no significant difference in over-all dry matter intakes. When the combined response of both breed types was considered there was a significantly linear decrease in live-weight gain with increasing straw intake, to the extent of 0.95 kg per week for each 10% increase in straw intake up to 40% in the diet. Similarly there was a significant increase in the conversion ratios of dry matter (P 〈 0·01) and organic matter (P 〈 0·01) with increasing straw intake. The effect on the dry matter conversion ratio was an increase of 1·67 units for each 10% increase in straw intake.Two digestibility trials were carried out, one with coarsely chopped straw and one with coarsely milled straw, the levels of straw in the diets being the same. There was a slight decline in the digestibility of most constituents associated with milling but reductions were not very pronounced. A treatment was included in the second trial in which milled straw was included at 20% of the diet without maintaining the over-all crude protein content of the diet. The apparent digestibility of the organic matter was 5 percentage units lower with this treatment than with that containing the same level of straw in which the level of protein had been maintained.

Description: SummaryThe results of three cotton irrigation experiments in the western Negev region indicate that by increasing the intervals between irrigations and by applying the first irrigation at the beginning of flowering, maximum yields of 1700–2100 kg/ha can be obtained with three irrigations. In all treatments except the one with four irrigations, about 0·31 kg of lint was produced for each 1 m3 of irrigation water. In the three driest treatments, where cotton suffered from moisture stress during various periods of growth, no differences in lint quality could be detected in comparison with wetter treatments. As long as there were clear drought symptoms, such as in the three driest treatments, additional irrigation increased the number of bolls/plant, while the average boll weight remained unaffected. Additional irrigation in treatments where there were no clear water stress symptoms did not increase the number of bolls/plant, but increased the average boll weight.

Description: SummaryA total of 512 pigs were given from 50 lb live weight one of 16 diets (four lysine levels at each of 12, 14, 16 and 18% protein), at one of four levels of intake. They were killed at 100, 150, 200 or 250 lb live weight and the carcasses jointed in a standard manner and right sides dissected into lean meat, fat, skin and bone.Mean percentage proportion of shoulder, middle and ham joints in the dressed sides at the four weights was 36·3, 36·4 and 27·3; 35·4, 37·9 and 26·7; 34·5, 39·6 and 25·9; and 33·8, 40·7 and 25·5, respectively. Mean percentage lean meat at the four live weights was 61·5, 59·9, 56·7 and 54·2 and the mean percentage fat was 20·7, 24·4, 29·4 and 32·8.Carcass quality was influenced significantly by dietary treatment and sex. Increasing the level of protein in the diet up to 16, 16, 14–16 and 14%, respectively, for the four live weight groups gave a significant increase in carcass leanness. Increasing the level of lysine in the diet did not have a very marked effect on carcass composition, while increasing feed intake to the highest level produced fatter carcasses at all weights. Carcasses of males were fatter and with a lower proportion of ham than those of females. Interactions involving dietary treatments and sex were described.Chemical composition of the m. longissimus dorsi was not altered markedly by dietary treatment or sex but dry matter and intramuscular fat content rose with increasing weight. Protein content of the dry matter remained fairly constant at all weights, while colour and shear value rose with increasing weight but were not significantly influenced by dietary treatment or sex.The pH values of the m. multifidus dorsi just after slaughter or on the day following were not markedly affected by dietary treatment, sex or weight.

Description: SUMMARYTwo sets of correlations among blood mineral concentrations were calculated (1) those attributable to the effects of various factors (breed, age, lambing performance, etc.) and (2) those remaining (residual) when the effects of such factors had been removed as sources of variation in mineral concentration (the equivalent of correlations within subclasses).Correlations arising from breed differences in mineral concentrations were highest for Ca.P (– 0·81), Ca.Cu (0·83) and P.Cu (–0·95). Correlations consequent on changes with the age of the sheep were most marked for Ca.Mg (0·97, P 〈 0·01) and Cu.K (–0·92, P 〈 0·05) and approximately 0·8 (P 〈 0·1) for Ca.K, P.Mg, P.K and K.C1.Residual correlations were all below 0–2 (although seven of the twenty-one were statistically significant, P 〈 0·05) suggesting that within subclasses most of the variation in the concentration of anyjone mineral was independent of that in the other minerals. Simple and partial correlations were very similar in magnitude suggesting that the associations found between pairs of minerals were not attributable to joint co-variance with any of the other five minerals.As the sheep grew older, changes in the concentrations of Ca, P and Mg were significantly correlated with the increases in live weight. Within subclasses, differences among the sheep in live weight were significantly (P 〈 0·05) and positively correlated with differences in the concentrations of Ca (r, 0·11), Mg (0·13) and Cu (0·11).

Description: SUMMARYA method of preparation of the whole bodies of pigs, suitable for the analyses of their mineral contents, has been described. Two litters of pigs were slaughtered at birth and another two at 8 weeks of age and each pig was analysed for whole body content, of Ca, P, Mg, Na, K and Cl. From another litter of pigs a gilt and castrated male were slaughtered at 23, 41, 54 and 90 kg live weight and their bodies analysed for the same elements. The data were used to derive a series of regression equations relating mineral contents to empty body weight for pigs at birth, 8 weeks of age and from 23 kg to 90 kg live weight. The regression coefficients, which provide a measure of the amount of a particular mineral retained in g/kg increase in empty body weight were, for pigs at birth Ca, 7·9; P, 6·3; Mg, 0·3; Na, 1·5; K, 1·9; Cl, 4·8; for pigs at eight weeks of age, Ca, 13·3; P, 7·4; Mg, 0·5; Na, 1·6; K, 2·3; Cl, 1·7; and for pigs from 23–90 kg live weight Mg, 0·4; Na, 1·3; K, 2·0; Cl, 1·1. For the older pigs Ca and P retentions (g/kg increase in empty body weight) ranged from 13·5 (Ca) and 7·6 (P) at 23 kg empty body weight to 4·3 (Ca) and 1·0 (P) at 90 kg empty body weight.

Description: SummaryTwo experiments are described in which the potential production of genotypes selected from within S. 321 perennial ryegrass for differing leaf length was assessed (a) in micro-swards composed of populations of similar genotypes and (b) in micro-swards of individual genotypes. In Experiment 1 the long- and short-leaved populations were also compared with the base population of S. 321 and with several other natural populations and bred varieties.Under infrequent cutting the population of long-leaved genotypes was more productive than the short-leaved and base populations. Under frequent cutting, however, the population of short-leaved genotypes was most productive. Similarly, whilst Ba 6280 ryegrass was highly productive and the natural Ynyslas population unproductive under infrequent cutting the situation was reversed under frequent cutting. The population of long-leaved genotypes and Ba 6280 had a higher leaf area index (L) than other populations and varieties at complete light interception.Considerable differences in productivity existed between individual genotypes, and there was also an interaction between genotypes and cutting frequencies. The relationships between yield and both leaf length and chlorophyll content are presented and the physiological basis of inter-genotypic and inter-population differences in production are discussed.

Description: SUMMARYBlood potassium and haemoglobin types were investigated in three breeds of sheep in India. Both high and low blood potassium types and all three haemoglobin types—A, B, and AB—were found to be present in two of the breeds examined, namely Bikaneri and Corriedale x Bikaneri. Mandia sheep had both potassium types but only two haemoglobin types—B and AB. Haemoglobin B and high potassium types predominated in all the three breeds; this would clearly point to the comparative suitability of these animals for relatively drier parts of India.

Description: SUMMARYThe experiment described here is the second of a series of experiments investigating the effect of the time of application of certain plant nutrients on the growth of the potato crop. In this experiment all combinations of three rates of nitrogen (0, 0·75 and 1·50 cwts nitrogen per acre), two times of application (at planting and at the time of tuber initiation) and two rates of application of CCC (0 and 4 lb/acre applied twice, shortly after emergence) were tested and studied by the technique of growth analysis.There was a linear relationship between leaf area duration (D)and tuber dry matter yield, D accounting for 95 % of the variation in the latter. The maximum amount of nitrogen accumulated in the leaves (Nmax) was linearly related to D, and accounted for 86 % of the variation in D. This relationship was improved if separate regressions were calculated according to whether CCC had been applied or not. Calculated in this way, the regressions indicated that more nitrogen was required for a given value of D when plants were treated with CCC.Delaying the application of nitrogen resulted in a considerable improvement in the recovery of fertilizer nitrogen (ammonium nitrate). A heavy dressing of nitrogen at the time of planting did not enable the crop to take up sufficient nitrogen for maximum yield. Because of these factors, delaying the application of nitrogen significantly increased tuber yield at both rates of nitrogen tested.Increasing the rate of nitrogen and delaying its application tended to increase the proportion of stem in the total dry matter; CCC had the opposite tendency. CCC, however, reduced leaf area and the mean effect of CCC was to reduce tuber yields. While there wore no significant interactions between CCC and nitrogen treatments on final tuber yield, it was observed that CCC slightly increased yield when the highest rate of nitrogen was applied late. Ways are suggested in which CCC may be more effectively used.

Description: SUMMARY1. Three methods, based on treatment with neutral detergent or acid detergent, or involving ultrasonic disintegration, are described and compared for the direct estimation of undigested dietary nitrogen in individual samples of sheep faeces. Estimates of the true digestibility of the nitrogen in several sheep diets derived from analyses performed with these methods agreed well with each other, and were in accord with published estimates, derived by extrapolation techniques. Two other methods, based on treatment with phenol–acetic acid–water, and lysozyme–trypsin, respectively, were found to be unsuitable for such estimates.2. The quantitative distribution of nitrogen between undigested dietary residues, bacterial residues, endogenous debris residues and the water soluble fraction was determined chemically. It was concluded that 57–81% of the non-dietary faecal nitrogen was associated with bacterial material.3. Indirect evidence suggested that most of the bacterial nitrogen in faeces originated in the rumen.

Description: SUMMARYThe intensive finishing of steers on simple rations of 10% sorghum stubble and 90% sorghum grain plus urea was investigated. Fine grinding of the grain resulted in a lower mean daily intake, but a significantly greater efficiency of conversion of feed to carcass weight gain (P 〈 0·01) than coarse grinding the grain. Coarse chaffing of the stubble significantly reduced the intake of the stubble in comparison with hammer milling, but had no significant effect on rate of body weight gain, total feed intake or efficiency of feed conversion.The addition to the ration of either 1 mg of selenium, or 200 mg vitamin E, 200 mg vitamin E and 100 mg vitamin K per day had no significant effect on rate or efficiency of body or carcass weight gain. Seven out of 32 steers which were not injected with 3 million i.u. of vitamin A at the start of the experiment exhibited nyctalopia. None of the 32 steers which received the vitamin A injection had hepatic vitamin A concentrations less than 33 μg/g. Vitamin A injection did not have a significant effect on the rate of body weight gain (mean ±S.E. 1·3 ± 0·03 kg per day), efficiency of feed conversion (10·4 ± 0·16 kg D.M. per kg carcass weight gain), or time to attain slaughter weight (133 ± 3 days). Drenching twice with thiabendazole had no significant effect on rate of body weight gain.

Description: SUMMARYA simple and rapid technique for estimating changes in fibre brush-end formation rate is described. The technique was used to give a quantitative estimate of the extent of brush-end formation induced by exogenous hormonal treatment of normal sheep and to establish the time relationship between treatment, fibre brush-end formation and the subsequent casting of the fleece.

Description: SUMMARYSubjectively assessed body condition scores, determined on the live animal, were related to the percentages of chemical fat in the fleece-free empty bodies of 30 adult Scottish Blackface ewes. The results show that body condition scores can provide an acceptable and useful estimate of the proportion of fat in the live animal, and that the level of prediction is superior to that afforded by live weight.

Description: SUMMARYIn an experiment to investigate growth in relation to nitrogen concentration and nitrogen uptake, Proctor was compared with four other varieties of barley at two levels of irrigation and two levels of nitrogen fertilizer by means of weekly samples throughout the growing season. The varieties were Deba Abed, a new variety recommended for high fertility conditions where feeding quality grain is required, and three exotic varieties, chosen for their high concentration of nitrogen in the grain.Irrigation stimulated tillering, although certain varieties responded more strongly than others; irrigation also led to a higher specific growth rate. Certain of the exotic varieties had high growth rates early in the season but growth fell off earlier due to earlier ear emergence. Maximum leaf area index was greater in the irrigated treatment at the high nitrogen fertilizer level. The adapted varieties had higher maximum leaf area indices than the exotic varieties, although some of the exotics had higher rates of leaf area growth early in the season; there were also differences in the way in which the varieties responded to irrigation. Irrigation and variety both affected the rate at which the percentage nitrogen in the shoot fell with time.Analysis of these data indicates that nitrogen uptake early in the season was an important factor determining the total amount of nitrogen taken up by the plant. It was also shown that the relative rate of decline of the specific growth rate and the specific rate of nitrogen uptake differed between varieties. Analysis of the specific growth rate indicated that differences in leaf growth, rather than net assimilation rate, led to the varietal differences. The differential response to irrigation is discussed with reference to drought resistance.

Description: SUMMARYFifty-nine Mutton Merino and cross-bred 2-year-old and older ewes were allotted to two groups according to age, weight and breeding performance in the preceding 1966/67 in-season. In the experimental ewes the treatment started on 22 March 1967 and consisted of vaginal sponges (Syncro-Mate) inserted for 17 days and 750 i.u./ewe of P.M.S. injected on the day of the removal of the sponges.As from 1 March, all the ewes were ‘teased’ daily but hand service commenced on 20 April, to coincide with the 13th day after the removal of the sponges.At the time of sponge insertion, approximately a third of the ewes, in each group, were already cycling. The treatment advanced the average post-treatment oestrus by 8 days, out of a possible 15 days, synchronized it in 70% of ewes and shortened the tupping season in 97% of treated ewes to 9 days (23 days in controls), but otherwise the performance of the treated ewes (and their offspring) did not differ from that of the controls. In both groups forty ewes lambed (68%) and fifty lambs were born (85%). Out of nineteen dry ewes, five were in anoestrus and in at least nine, an early death of the embryo could be suspected. Among the reproductive activities during the preceding in-season, date of weaning, days of suckling and barrenness may be implicated in the failure to breed in the spring.

Description: SUMMARYA total of 512 pigs were given from 50 lb live weight one of 16 diets, i.e. with 4 lysine levels at each of 12, 14, 16 and 18% protein, at one of 4 levels of intake. They were killed at 100, 150, 200 or 250 lb live weight.Live-weight gain was not improved significantly by increasing the protein level above 16, 14, 12and 12%, respectively, for the 50–100, 100–150, 150–200and200–2501bstages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the protein to 18%. Gain in lean meat and in the efficiency of conversion of feed to lean meat were improved by increasing the above protein levels slightly.Live-weight gain was not improved significantly by increasing the lysine level above 1·04, 0·74, 0·70 and 0·59%, respectively, for the 50–100, 100–150, 150–200 and 200–250 lb stages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the lysine level to 1·22%. Raising the lysine level at each level of protein had no significant effect on the rate and efficiency of lean meat gain.Live-weight gain was significantly improved by increasing the level of feed intake almost to ad libitum levels for the 50–100, 100–150 and 150–200 lb stages. There was a suggestion of a similar effect in the 200–250 lb pigs although it was not statistically significant. Conversion of feed to live-weight gain was improved in the 50–100 lb pigs only by increasing the level of feed intake: in the older pigs increasing the level of feed intake caused a worsening in feed conversion ratio. Increasing the level of feed intake gave a significant improvement in rate of lean meat gain but a significant worsening in the efficiency of conversion of feed to lean meat during all stages up to 200 lb.Interaction effects of these factors and sex, on growth performance, are described.

Description: SUMMARYIncreases in nitrite in ten gamma-irradiated soils have been investigated under aerobic conditions up to 7 days after treatment over the range 0·25–2·5 Mrad. The formation of nitrite showed significant correlations with the percentage of soil inorganic carbon and incubation time, and over 100 ppm nitrite-N accumulated within 3 days in Broadmoor series, which contained the most inorganic carbon. Only the very acid series failed to produce nitrite, but formation and persistence was poor in all soils below pH 7.Leaching with ammonium or nitrate ions after irradiation suggested that microbial reduction of nitrate was the mechanism responsible for nitrite accumulation, rather than inhibition of nitrite oxidation.

Description: SUMMARYThe biological and economic performance of a cotton crop are examined. The effects of variety, water, sowing date and spacing on crop performance are considered in relation to their effects on crop growth, which had been studied previously, or noted in the literature. Suitable varieties and agronomic practices are discussed. An empirical relationship between available water, dry matter production and yield of seed cotton is evaluated physically and biologically on the basis of Penman's and de Wit's work, and practically in the light of commercial yields and rates of watering.

Description: SUMMARYThe effect of maturity on the nutritional quality of hay from two alfalfa varieties and four grass species was studied. Each hay was harvested at six different stages of growth, chopped in 4–6 cm lengths, and fed to sheep in quantities of 10% in excess of voluntary intake. The relationship between intake (Y) and digestibility (X) of dry matter was best expressed by regressions of the form: Y = a + b1X + b2X2. The rate of intake declined 1·5 g daily per kg0·75 of body weight per unit decrease in digestibility percentage, and was the same for both alfalfa and grass hays. However, the intake of alfalfa hay was about 10% higher than that of the grass hays of similar digestibility. No differences in the relationship between intake and digestibility (P 〈 0·05) were observed between the two alfalfa varieties or between the four grass species. When the nutritional quality was expressed as voluntary intake of digestible organic matter daily per kg0·75 of body weight, and time of harvest as day-number of the year, the difference in quality between the six kinds of hay was very small or absent at the beginning of the season (immature to prebloom) and increased toward maturity (dough stage to seed ripe). The decline in quality of alfalfa hay was slower than that of grass hay, and ceased at the mature to overripe stage. On the average, voluntary intake of digestible organic matter declined 0·29 g daily for each day delay in harvest time; this decline varied from 1·2% of the daily intake of digestible organic matter in the beginning of the season to 0·6% at the mature stage. Time of harvest ‘accounted for’ 77–89% of the variation in the quality of the hays. The confounded effect of maturity and leanness on the nutritional quality of the hays was expressed best by concave, second degree polynomial regressions. On the average a unit decline in percent leaves corresponded to a decline of 0·58 g and 0·73 g respectively in the daily intake of digestible organic matter from alfalfa and grass hay. This varied from over 1 g early in the season to less than one tenth of a gram late in the season. The confounded effect of leafiness and growth stage ‘accounted for’ over 75% of the variability in nutritional quality. The relationship between intake and digestibility of the alfalfa and grass hays was used to illustrate how voluntary intake of metabolizable energy (percent of requirement for maintenance) from hay of pure or mixed species may be predicted from in vitro digestibility.

Description: SUMMARYColchicine induced 64-chromosome white clover was compared at a number of centres with control material (2n = 32), as spaced plants and in broadcast plots with and without companion grasses.The chromosome-doubled material generally conformed to the well-known reaction of polyploids; the plants were later flowering, had thicker petioles and stolons, broader leaflets and spread less vigorously. Yield of green matter of spaced plants was much less, and in broadcast plots the gross yield (grass + clover) and that of the clover fraction was 7% less than in comparable S. 100 plots. The Finlay-Wilkinson analysis indicated that the chromosome-doubled form did not respond to improved conditions to the same extent as did the control varieties. The presence of grass in the mixture partly compensated for low clover yield, but was insufficient to increase total yields to that of S. 100 controls.

Description: SUMMARYA subclinical calcium or phosphorus dietary deficiency on many hill pastures and a relationship between this and the premature loss of permanent incisor teeth are postulated. The effects of small individual supplements of calcium (12 g calcium carbonate suspended in water) or phosphorus (13 g monosodium phosphate in solution) supplied three times a week between mid-February and the end of May to Scottish Blackface ewes which grazed reseeded pasture in April and May were compared with those of no mineral supplement and with those of no mineral supplementon hill pastures throughout.Neither supplement had any significant effect on the number or weights of lambs born or reared on reseeded pastures. Both resulted in significantly greater ewe live-weight gain during the treatment period, in a significant improvement in the firmness and permanence of the incisor teeth, and in significantly higher serum Ca levels during lactation. All effects increased with advancing age.The use of hill pastures during late pregnancy and early lactation without any mineral supplement could result in significantly poorer ewe live-weight gain during the treatment period depending on season. This was also associated with significantly lighter single lambs at 6 weeks and with slower deterioration of the incisor teeth.It is suggested that minerals lost from the body during lactation on reseeded pastures are not replaced during the autumn recovery period on hill pastures and that a gradual depletion occurs throughout life, leading possibly to demineralization of the alveolar bone and premature loss of the incisor teeth. It is suggested that this is indicative of a higher mineral requirement for maintenance of the permanent dentition than is necessary for normal acceptable growth andreproductive performance. Mineral content of hill herbage may therefore be too low to supply requirements at the levels of OM intake normal on hill pastures.

Description: SUMMARYInvestigations into the non-protein nitrogen composition of grass silages using the 50 cm strong cation-exchange column of Spackman, Stein & Moore (1958) to determine the basic amino acids led to difficulties in the determination of ethanolamine in the presence of high concentrations of ammonia, and of histidine in the presence of δ amino-n-valeric acid. An alternative technique for the ion exchange chromatography and estimation of histidine, lysine, ornithine, ethanolamine, arginine and ammonia on a weak cation-exchange resin has been developed. This method enables small amounts of ethanolamine to be determined in the presence of large amounts of ammonia and values for the ethanolamine content of a number of silage samples are presented. When used in conjunction with the technique of Spackman et al. (1958) the δ-amino-n-valeric acid content of grass silages could also be determined in the presence of histidine.The estimation of amines produced by the microbial decomposition of herbage proteins during ensiling has previously involved their initial separation from the amino acids followed by quantitative partition chromatography. An alternative method for the estimation of these amines by ion-exchange chromatography on a weak cation-exchange resin is described. This method permits the colorimetric determination of β-phenylethylamine, tyramine, tryptamine, 5-hydroxytryptamine, putrescine, cadaverine and histamine without interference from the amino acids. The efficiency of this technique has been investigated using standard solutions of the naturally occurring amines and samples of good quality and of high pH spoilt silages.

Description: SUMMARYTwo-hundred-and-seventy-three Scottish Blackface ewes in three ages (5, 4 and 2 years) were differentially group fed over 6 weeks in such a manner that at 6 weeks before mating there were approximately equal numbers in each of six subjectively assessed body condition groups ranging from score 1 (lean) to score 3½ (moderately fat). Over the 6 weeks prior to mating these groups were either well fed, fed at about maintenance, or underfed so that at mating the maj ority of ewes were in either condition 1½ or 3.A predetermined random sample of mature ewes from each of the six original condition groups was killed 2–3 days post-mating for ovulation counts. Surviving ewes were fed above maintenance post-mating and the number of lambs recorded at birth. Condition at mating had a significant, positive effect on both ovulation and lambing rates but had no effect on infertility measured as the difference between them.The level of food intake prior to and at mating had no effect on either ovulation or lambing rates of moderately fat ewes (condition 3) but the results can be interpreted as indicating that the level of food intake had a positive effect on both ovulation and lambing rates of lean ewes (condition 1½).

Description: SUMMARYForty-two Persian Blackhead ewes were used to investigate the effect of three prenatal planes of nutrition 6 weeks before lambing on birth weights and weights at 4 and 12 weeks after birth of their progeny. Nutritional regimes were: good grazing with concentrate supplement (high), good grazing without supplement (medium) and poor grazing without supplement (low). Pastures used were rotationally grazed Pangola grass. High-plane ewes gained significantly more weight during the last 6 weeks of gestation than ewes of the other two groups. Ewes nursing twin lambs lost significantly more weight than ewes nursing singles during the first 4 weeks of lactation. Birth weights of male single lambs and lambs from mature ewes were significantly affected by the prenatal plane of nutrition of the ewe. Lambs from mature ewes weighed significantly more than lambs from maiden ewes and male lambs weighed significantly more than females. Live-weight gains to 4 weeks were significantly affected by prenatal plane of nutrition in all cases. Type of birth was an important factor affecting growth rate and maturity of the ewe less so. Male lambs gained more weight than females during this period. Similar tendencies were apparent during the growth period of 4–12 weeks after birth although rate of gain was lower.

Description: SUMMARYThe effects of several dietary regimens on the fat-free mass and the dry-matter, ash and potassium-40 content of selected bovine muscles were estimated. Muscle data from 104 half-sib Angus steers were secured at several stages of growth and after several feeding regimens. The results indicated that a hay diet, by comparison to a higher energy silage diet in the early feeding period (216–340 kg live weight), suppressed the fat-free weight, reduced the dry-matter content and increased the ash content of several muscles. These effects of early diet were reversed, however, when the animals were subsequently fed higher-energy rations and slaughtered at heavier weights (409 and 454 kg live weight). Data on potassium-40 gamma emissions by composite muscle samples confirmed the existence of age- or weight-associated decreases and suggested possible dietary influences on potassium levels in bovine muscles. The trends in these data indicated that low dietary energy (hay feeding) in the early feeding period delayed the decline in muscle potassium that normally accompanies maturation.

Description: SUMMARYResults of genetical tests in the Sudan are consistent with those of Arnold (1963), who was unable in Tanzania to transfer the bacterial blight intensifier gene, B6, as a separate entity to local cotton. Confirmation was obtained of the presence of B2 in Mwanza Local. The high resistance of UKBR selections from Mwanza Local was found to result from the interaction of B2 with a gene, or complex of genes, occupying the same locus as B6, or closely linked to it. This B6-type gene was obtained by exerting steady selection pressure over a number of years and gradually increasing resistance; it therefore reveals that during the last 50 years blight resistance in African Uplands has evolved per se. Whether all of Knight's (1957) B genes have arisen in such a way, or by point mutation, is conjectural.

Description: SUMMARYThe use of tritiated water to estimate total body-water content of animals experiencing recovery from under-nutrition was studied.The time for equilibration of tritiated water (TOH), given intraperitoneally, with total body water (TBW) was determined in rabbits and in rats. As judged by the specific activity of blood water, equilibration had occurred by 76–125 min in the rabbit and did not appear to be affected by the plane of nutrition. However, between slaughter groups the specific activity of water obtained from the liver 180 min after injection of TOH was significantly different from the specific activity of water simultaneously obtained from the blood plasma. It is concluded that the liver is not a suitable tissue to use for testing achievement of equilibration.As judged by the specific activity of blood water compared to that of water from the whole body macerate, equilibration in mature rats either in stable body condition or undergoing rapid compensatory growth occurred in less than 60 min.A trial comparing TOH-space (corrected by 3% body weight) and actual TBW (by desiccation) was conducted on thirty rabbits which experienced under-nutrition followed by compensatory growth.Prior to under-nutrition the agreement between actual and estimated TBW was satisfactory and within 2·3%. During compensatory growth the agreement was poor— the TOH values over-estimating actual TBW by about 12%.A trial with mature rats confirmed the findings with rabbits. For rats in stable body weight the mean estimated TOH-space for fourteen animals was within 1·2% of the actual TBW. For fourteen rats undergoing compensatory growth the mean estimated TOH-space (corrected by 3% body weight) overestimated actual TBW by 6·2%.

Description: SUMMARYEight feeding trials on cattle showed that the response in live-weight gain was curvilinear when protein or energy level was varied independently in rations based on poor quality roughages to which cereals and groundnut were variously added to give a range of protein and energy intakes. Live-weight gain was increased by 0·12 lb/day for each 0·1 lb additional digestible crude protein/day at levels of intake below 0·7 lb/day and by 0·03 lb/day at higher levels. It was increased by 0·4 lb/day for each additional 0·1 lb starch equivalent daily/100 lb live weight at total intakes below 0·9 lb daily/ 100 lb and by 0·2 lb/day at higher levels. Over the range 0·5–2·0 lb digestible crude protein daily and 0·7–1·2 lb starch equivalent daily/100 lb live weight the effects of these nutrients were additive.A Latin square nitrogen balance trial demonstrated that a portion of the nitrogen from a protein supplement was retained in the body despite the excretion of the greater part of it in the urine and a further part in the faeces. Nitrogen retention was increased by a supplement of readily available energy through a decrease in urinary nitrogen loss. Nitrogen balance was not increased by a supplement of a fibrous energy source because this induced an increase in faecal nitrogen loss.In a further feeding trial milk yield was found to be affected in a similar manner to growth. At a yield of 30 lb/day the response per lb starch equivalent added to the diet was 0·5 lb milk including 0·05 lb solids not fat and to an increase of 0·1 lb digestible crude protein daily it was 0·25 lb milk including 0·025 lb solids not fat.

Description: SummaryAn experiment was conducted with 32 spring-born Friesian heifer calves, purchased at an average age of 10 days and fed on cold reconstituted milk substitute at pasture.The milk feeding treatments were 4, 4½, 6½ and 9½ weeks in length, during which time calves consumed an average of 17, 23, 43 and 70 kg dry matter/head of milk substitute respectively. The differences between treatment mean live-weight gains for 10½ weeks of the experiment were highly significant (P 〈 O·OOl): the gains were 0·49, 0·43, 0·64 and 0·78 kg/head/day. There was no significant difference between mean rates of live-weight gain after the tenth week so that the overall treatment—mean live-weight gains for the first 23 weeks, which were 0·65, 0·61, 0·72 and 0·74 kg/head/day, strongly reflected the length of the milk-feeding period and demonstrated no significant compensatory growth by the calves.Twenty of these animals were housed for the subsequent winter period and were returned to pasture for a second grazing season. These were artificially inseminated as their individual live weights reached approximately 320 kg. Animals weaned after only 4 weeks of milk feeding took an average of 9½ weeks longer to reach live weights of 320 kg than these receiving milk for 9½ weeks. There were no marked indications of compensatory growth during this extended period of observations.

Description: SUMMARYA comparison was made of six different methods of inoculation with Cercosporella herpotrichoidesFron on field plots of the spring barley variety Impala. All inoculation treatments produced significant differences in terms of disease incidence and grain yield compared with the uninoculated controls. Significant differences were found between treatments in terms of disease incidence, disease severity, mean yield/head and 1000 grain weights. The time of inoculation was also found to be significant. The earlier inoculation caused a reduction in yield of approximately 66 % compared with 50 % at the later inoculation. The application of these methods is discussed.

Description: SummaryThree dry cows, each fitted with a permanent rumen fistula, were fed hay and flaked maize or hay and rolled barley in widely different proportions. All rations were offered at 7 kg dry matter daily for 3 weeks following hay alone. The cows refused all cereal 3 or 4 days after introduction of rations including 80 and 100% flaked maize; recovery of intake occurred in most instances within a further 3–10 days. On the 100% flaked maize ration, the refusals were associated with very low pH and high concentrations of lactic acid in the rumen.Refusalsof rolled barley were small and showed no clear pattern.Rumen fermentation was reasonably stable during the last week of each period except with the 100% barley rations. On the rations containing flaked maize, molar proportions of volatile fatty acids (VFA) varied widely but on only one occasion did the proportion of acetic acid fall below 55% and in two cows that consumed flaked maize alone, the proportion of acetic acid in the rumen exceeded 60%. On the rations containing rolled barley, increasing proportions of barley were associated with large decreases in the proportion of acetic acid and increases in the proportion of propionic acid. The maximum proportion of n-butyric acid was found on the rations containing 50% cereal.It is suggested that, when large proportions of cereals are fed, the proportions of VFA bear no clear relationship to the crude fibre content of the ration but that an association with rumen pH may exist.

Description: SummaryA traditional type score card for ten carcass characteristics was tested against an experimental reorganization of this card on a simplified 7 point scaling system. Results showed that both experienced judges and novices were more consistently discriminating when using the revised system. This was most evident when the concept of an optimum was eliminated from the judgements. It was also evident when complex judgements which do not involve an optimum were simplified. The scale of marks and the diversity in maximum marks for different characteristics appeared to have less influence upon consistency and discrimination. However, it is probable that, with traditional cards, the maximum marks are often too high and that the diversity in total possible marks adds a further difficulty for judges.

Description: SummaryTwenty-four sugar-beet plants were cut into quarters, planted and allowed to produce fruit under varying fertilizer and irrigation treatments. Studies on the germination rates of these clusters showed that there were marked genetic differences between the clones. Wetting the seeds continually by overhead irrigation, to simulate heavy rainfalls markedly decreased the rate of germination, apparently by delaying the onset of maturity. Immature clusters from early harvests of plants which were not irrigated also showed a decreased germination capacity. The fertilizer treatments in this experiment were less important as a source of variation than the clonal and irrigation components. The results may be related to the presence of germination inhibitors in the clusters but there may be important changes in the embryos of the seeds themselves.

Description: SUMMARYStatistical analyses were carried out on the data obtained under strictly controlled conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.The authors have calculated and studied the correlations between faecal and urinary sodium losses, sodium excretion in the milk, digestible sodium and sodium balance and the 75 other nutritive factors which were analysedfor each of the 55 above mentioned experimental diets.The most important factor in the fate of sodium is the amount of dietary sodium. Sodium digestibility is neither total nor constant: faecal losses and digestible amounts are enhanced when sodium intake is increased and faecal losses are also positively correlated with dry matter and nitrogen intakes. An increase in digestible sodium benefits both urinary excretion and balance, the latter being reduced by an increase in dry matter and nitrogen intake.Sodium balance is always negative when sodium content of the diet is lower than 0.1% in the dry cows and 0.2% in the lactating cows. In our experimental conditions, the sodium requirements for milk production do not influence sodium digestibility, but are met above all to the detriment of urinary losses.

Description: SUMMARYVariety, sowing date, irrigation water and plant spacing were the variables in five experiments over three seasons in southern Arabia. The results are used to develop the idea that morphological change and increase in dry weight—two aspects of the growth of cotton which are often studied separately—must be linked to explain or predict crop performance.A straight line related the number of flower buds counted at any time to the number of mainstem nodes on a plant. The mainstem was therefore a simple parameter for the effect of age, temperature and water on the development of plant structure. The relationship was explained by a model in which fruiting branches compete with one another. The structure of the crop plants, as measured by the types and number of nodes, developed along a course in time determined by variety and spacing at a rate dependent on temperature. The rate decreased with age, but was independent of the quantity of water available, until a critical amount had been used, when development stopped abruptly.Accumulated day degrees accounted for the differences between dates of sowing in the subsequent production of nodes. This relationship was consistent with work on temperature elsewhere. Date of sowing effected the position of the first fruiting branch in the variety Bar XL 1 but not in Wild's Early. The position of the first fruiting branch and spacing affected the number of vegetative branches. Wider spaced plants produced flower buds faster only because they had more fruiting branches, a result in turn of more vegetative branches. The ratio between the mean rates of production of nodes on vegetative branches, and on fruiting branches were varietal constants and agreed with results elsewhere in contrasting conditions.

Description: SUMMARYOn the College of Agriculture farm in Abu-Ghraib 147 ejaculates were collected from three docked and four normal Awassi rams born during November 1962. The work covered a period from 1 April 1967 to 31 March 1968.Nine semen characters, namely, volume, mass activity, individual motility, sperm concentration, sperm number, pH, methylene blue reduction time and the percentages of abnormal and dead sperms, were studied. The effect of season and docking on these characters was investigated.Seasonal variation was observed in all traits studied. On the whole, semen quality was poorest during winter and best during summer. The effect of docking was more pronounced on sperm concentration, sperm number and percentage of abnormal sperms. Docking appeared to increase sperm production and reduce sperm abnormality.

Description: SUMMARYIn a factorial experiment the effect of two protein intakes and three patterns of feeding in the second pregnancy of 48 Large White x Wessex Saddleback sows was examined. The high protein (HP) diet (19·5% crude protein) contained 15% white fish meal. The low protein (LP) diet (10·5% crude protein) contained cereal protein only. Nutrient components of the diets differed in protein only. The pattern treatments involved allowances of 1·8 kg (L), 2·7 kg (C) and 3·6 kg (H) per day, the three pregnancy patterns being HL, C and LH with the changeovers made from the 49th to the 63rd day post coitum (p.c). Sows on the three pattern treatments received the same total amount of feed from 0–112 days p.c. and were treated alike at farrowing and during lactation.Fertility and parturition results were similar for all treatments, but the number of piglets alive after birth (when weighed) was least for LP sows on the HL pattern. At 3 weeks of age the size and weight of litters on HP sows were significantly greater than those on LP sows (P 〈 0·05 and 〈 0·001 respectively). More piglets were weaned by HP sows than LP sows (P 〈 0·05). HP sows gained more weight in pregnancy (P 〈 0·001) which was slightly longer, and lost more weight in lactation (P 〈 0·05) than LP sows.The HL pattern of feeding was associated with smaller live weight gains in pregnancy than the LH pattern (P 〈 0·001) and the total birth weight of HL litters was lighter than LH (P 〈 0·05), mean piglet weights being similar. Lactation performance was unaffected by pattern treatment.The main conclusion is that a low intake, particularly during the latter half of pregnancy, of protein which is of vegetable origin, is associated with decreased viability of the piglets at birth and in early suckling life, and with lower capacity of the sows for milk production.

Description: SummaryA series of three large-scale field trials, involving 3500 ewes over a 3-year-period, was conducted to study the effect of restricted nutrition of breeding ewes in early pregnancy. Control or non-restricted ewes were fed at approximately maintenance level and restricted ewes at approximately half-maintenance. The majority of ewes fell into two categories—those 2–3 weeks pregnant at the time restriction was commenced and those 5–7 weeks pregnant. Restriction was applied for from 5 to 8 weeks, live-weight differences of approximately 10 1b were achieved.Differences in performance in individual trials were invariably very small, and nonsignificant. The main effect of restricted nutrition over all trials was to decrease twinning by 0·5% and decrease the number of barren ewes by 0·8%. These differences are considered to be negligible. Only one statistically significant effect was observed within one of the trials—this was a depression in twinning in ewes 18–24 days pregnant at the time of applying the treatment, but this effect could not be confirmed in the other two trials. However, the fleece grown was affected by treatment—the fleece weight being depressed by approximately ½ lb, and grade reduced slightly.It is concluded that restricted nutrition at the level and time applied has no effect on reproductive performances of ewes and therefore the practice of restriction in early pregnancy to conserve feed for late pregnancy is a sound policy.