Two uniformity trials were carried out, one using S. 22 and the other Irish Italian ryegrass. In both trials the plants were grown at 6 in spacing and were harvested in basic units of 1 yd. If no allowance was made for guard rows the smallest plots were the most efficient in that they required a smaller total area of ground and fewer plants to detect a specified difference. For comparative purposes, the size of trial required to detect a difference of 7% of the mean was used. Allowing for 1 guard row round each plot, 2 yd plots were as efficient as those of 1 yd and had the advantage of requiring fewer replications. The effects of plot and block shape were considerable. In general long narrow plots in short wide blocks were more efficient. The choice of plot and block shape is most important. For a given plot size a poor shape may be less than half as efficient as a good one.

Groups of Awassi lambs, aged 7–13 months at start of the trial, were fed for 100 days on four different rations. A ‘control’ ration contained ground barley: the others contained different proportions of dried sugar-beet pulp, and no barley.

Male lambs were initially heavier, and gave better weight gains than the females. Groups on beet pulp grew better than the ‘control’. The most economical weight gains were obtained in the group in which beet pulp constituted 40 % of the ‘concentrate’ portion of the diet.

Sulphur content, expressed as a percentage of clean dry wool weight, was measured at monthly intervals in two breeds of sheep, Cheviot and Merino x Cheviot backcross (¾ Merino, ¼ Cheviot), offered an equivalent annual amount of feed in three ways—constant level, natural grazing cycle and reversed grazing cycle. The relationships between S content and wool growth rate or nutrient intake differed with both breed and nutrient cycle, but all the results could be explained satisfactorily on the basis of a constant optimum composition for each individual with sulphur impoverishment related to lack of balance between follicle activity rate and high-S substrate availability.

The difference in mean maximum S content between breeds (3·87% and 3·81% for Cheviot and ‘Merino’ respectively) was much smaller than the difference between individuals within the breeds (4·05·3·72% and 3·92·3·66%). The seasonal depression within individuals varied with nutrition and wool growth rate, Cheviot sheep showing the greatest depression and lowest values (2·89 and 3·28% for Cheviot and 'Merino, respectively in the reversed cycle group). There was no consistent seasonal trend in the relationship between clean and unscoured wool weight.

Three years' data on a herd of Sudanese cattle were used to study the influence of sex and sire on their growth from birth to 1 year of age. The traits studied included body weights at birth, weaning and yearling ages, and body measurements at birth and weaning age. Analysis of variance indicated no significant sex by sire interactions. Male calves had significantly (P < 0.01) heavier birth, weaning and yearling weights and faster pre-weaning average daily gain than female calves. There were no statistically significant differences between sexes in post-weaning gain or body measurements. The sire effects were highly significant (P < 0.01) for birth and yearling weights and postweaning average daily gain, but not for weaning weight and pre-weaning average daily gain. Sire effects were also significant (P < 0.05) for height at withers and heart girth at birth and weaning age and for body length at weaning age. The heritability estimates of birth and yearling weights and post-weaning gain were relatively high, whereas the heritability estimates of weaning weight and pre-weaning gain were low.

Two experiments designed to provide data for the estimation of functional relationships, which may be used to determine economically optimum plant populations and planting patterns in Desire'e potatoes, are described. Functional relationships between the number of main stems per acre and yield per acre were estimated from the results of experiment (i). Experiment (ii) investigated the relationship between stem number per tuber and seed tuber weight. ‘Square root’ functions estimated for seed yield and ware yield from the results of Exp. (i) were used to calculate a total Financial Returns curve. This returns curve, together with the Cobb-Douglas function estimated from the results of Exp. (ii), was used to calculate the stem numbers per acre, which would give maximum returns per acre and economically optimum returns in different cost/price situations.

Three granular nitrophosphates containing 5, 26 and 50 % of their total phosphorus in a water-soluble form, granular potassium metaphosphate, Gafsa rock phosphate and basic slag (both as powders) were compared with granular superphosphate and powdered dicalcium phosphate as standards in two annual experiments with ryegrass and in three experiments with barley.

In 1960 total yields of ryegrass during a whole season were similar with all fertilizers. Nitrophosphate-5, Gafsa rock phosphate and basic slag acted more slowly than granular superphosphate and grass grew less well and took up less phosphorus during the first 12 weeks. Over the whole growing season more phosphorus was taken up by grass from powdered dicalcium phosphate and from granular potassium metaphosphate (0.5–2.0 mm) than from granular superphosphate (1.0–4.0 mm).

Powdered dicalcium phosphate was equivalent to about 60% as much phosphorus applied as superphosphate to barley. Rock phosphate was almost inert and percentage granular superphosphate equivalents of basic slag and potassium metaphosphate were 22 and 23% respectively. Percentage superphosphate equivalents of the granular nitrophosphates were 1, 25 and 53% and almost equal to the water-soluble phosphate they contained.

The residual value of three nitrophosphates, potassium metaphosphate, basic slag and rock phosphate was compared with that of superphosphate in two experiments with potatoes, barley and swedes grown in rotation. The residual value of the fertilizers was also compared with that of (a) six cumulative annual dressings of superphosphate supplying either one-half or the same total amounts of phosphate and (b) single fresh applications of superphosphate applied once in each rotation. Yields and phosphorus uptakes are discussed in relation to the amounts of soil phosphate soluble in 0·5 M-NaHCO3.

In the first rotation residues of rock phosphate produced about 1 ton/acre less potato tubers than residues of other fertilizers and cumulative annual applications of superphosphate produced 0·6–0·9 tons/acre less tubers than all residues except rock phosphate. In the second rotation residues of fertilizers increased tuber yields less than cumulative dressings of superphosphate. Over two rotations mean yields from residues and from cumulative dressings were the same. Mean yields of barley over two rotations were 1–3 cwt/acre greater from residues than from cumulative annual dressings; the residual value of the different phosphates was the same. For swedes residues from the alternative phosphates, including basic slag and rock phosphate, were equivalent to those from superphosphate and gave the same mean yields as six cumulative dressings of superphosphate broadcast at planting.

Average residual values of alternative phosphate fertilizers, calculated from (a) yield response, (b) P uptake, and (c) soil analysis were: superphosphate, 100; nitrophosphates, 100–102; potassium metaphosphate, 95; basic slag, 94; Gafsa rock phosphate, 92. Mean percentage ‘fresh’ superphosphate equivalents of residues from all fertilizers were 17 and 26% after the first rotation and 11 and 15% after the second rotation for potatoes and swedes respectively.

The percentage of the total variance in crop yields accounted for by linear regression on NaHCO3-soluble P ranged from 38 to 70% for potatoes, 9 to 28% for barley grain and 42 to 92% for swedes. Mean yields of the crops increased by 0·24 ± 0·037 tons/acre (potatoes), 0·22 ± 0·08 cwt/acre (barley) and 1·16 ±0·148 tons/acre (swedes) for each ppm NaHCO3-soluble phosphorus in the soil at harvest.

The biuretolytic activity of the ruminal flora which developed in the ingesta of Merino sheep in response to feeding biuret with practical rations was demonstrated. The activity was determined by measuring the rate of disappearance of biuret in an in vitro fermentation system. Biuret was determined by a specific, semi-micro, colorimetric method based on the formation of a yellow nickel-biuret complex and adapted for use with ruminal fluid. The activity was evoked only when biuret was included in diets of poor quality teff hay with or without maize meal. With ruminal ingesta from sheep fed teff hay and biuret the activity was low, but when maize meal was given in addition the activity was about three times as high, and sufficient to account for the disappearance of up to 16–4 g daily in Merino sheep with a volume of ruminal ingesta of 61. The course of development of biuretolytic activity is discussed in relation to retention of biuret-nitrogen.

The teat-length increases observed in wether lambs grazing pure legumes have been compared directly with the oestrogenic activity demonstrated in mice fed samples of these pastures.

In the case of red clover, the mouse assay gives a good indication of the oestrogenic effect to be expected in the wethers. There was no such correlation when samples of clover and lucerne were tested. These were much more active in the wethers than would have been anticipated from the mouse assay, where lucerne and white clover appeared almost entirely lacking in oestrogenic activity.

In an experiment on nine Kumaoni bullocks, the effect of supplementing paddy straw rations with calcium carbonate or lime was studied. The digestion coefficients of dry matter, crude protein, ether extract and total carbohydrates and balances of nitrogen and phosphorus were not significantly affected by such supplementation; the calcium balances were significantly improved. It is concluded that supplementation of paddy straw rations with calcium carbonate (which is cheap and easier to handle), or with slaked lime, can be used with advantage in combating the problem of negative calcium balances frequently encountered on paddy straw rations. Incorporation of a small quantity of wheat bran (about 4 oz) helps in meeting the phosphorus requirement of adult animals.

Five non-pregnant ewes and seventeen ewes at various stages of pregnancy were fed on a medium quality hay for several weeks before being slaughtered and frozen. Each ewe was sawn into 5 cm cross-sections.

The sections were photographed. The uterus was extracted from the sections and its volume measured. Volumes of reticulo-rumen contents, intestinal contents and abdominal fat were estimated from the photographs.

Models of the uterus and rumen were constructed and examples of these and of the photographs are shown.

The volume of the uterus increased steadily as pregnancy progressed, but rumen volume was not reciprocally depressed until the last 5 weeks of pregnancy. Volume of digesta was inversely related to volume of incompressible abdominal content (uterus and fat). Abdominal fat was a particularly important factor in the depression of rumen capacity in pregnancy when there was great competition for space in the abdomen.

Eighty-nine cattle were treated to induce high superovulation with 3000 i.u. PMSG on day 16 of the cycle and slaughtered shortly after breeding and injection of 2000 i.u. HCG. In the 79 cattle that came in oestrus, the mean number of ovulations was 9.0. The percentage of follicles ovulating and the mean ovulation rate increased markedly as the interval between PMSG and oestrus increased from 2 to 5 days. Seventy-one percent of eggs shed were recovered; 68% of eggs recovered were cleaved. Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.

Culture studies were conducted with eggs recovered from cattle following super-ovulation treatment. Transfer of eggs to pseudo-pregnant rabbits led to continued cleavage in 71 of 138 attempts. Culture of eggs in vitro met with limited success in 58 of 189 attempts. The maximum cleavage stage reached in the in vivo studies was 64 cells; in the in vitro work it was 24 cells.

Ewo milk yield data obtained by the lamb suckling technique from nutritional experiments were analysed statistically to obtain estimates of the several components of variation. Diurnal variation was studied. The fitting of a sinusoidal curve removed a significant amount of variation.

There was a highly significant correlation between successive milk yields obtained at 4 h intervals. Number of lambs suckled and body weight of ewe at parturition had a significant effect on total daily milk yield.

The variation within ewes after the removal of diurnal variation and between ewes after the removal of the effects of number of lambs suckled and body weight at parturition were computed. These sources of variation were combined in a general equation which enabled the prediction of the standard errors associated with daily milk production for a given sampling technique. The practical application of the predicted standard errors is discussed.

The effects of annual applications of up to 300 lb/acre of N, 100 lb/acre of P2O5 and 200 lb/acre of K2O on cut swards of S. 24 ryegrass, S. 37 cocksfoot and S. 215 meadow fescue were measured in an experiment lasting 3 years.

There were some differences between species in their dry-matter and nutrient yield response to nitrogen and potash applications, but not to phosphate. These differences were inconsistent and over the 3-year period were negligible.

A large response to nitrogen was only fully maintained when phosphate and potash were also applied. There was no response above 50 lb/acre of P2O5 in any year. In the second year, 100 lb/acre of K2O was sufficient, but more than this was necessary in the other years. Symptoms of phosphate and potash deficiency were seen where high rates of nitrogen were applied without phosphate and potash respectively.

Using Persian Blackhead ewes, milk composition and the effect of diet on content of milk fat and milk yield were investigated. Analysis of the milk of nine ewes for fat, protein, ash and lactose (by difference) throughout a twelve-week lactation gave results which were compared with those in the literature. Average values were 5·9, 5·6, 1·0 and 4·8 % respectively. The milk of nine ewes fed on a high plane of nutrition contained significantly more fat than that of ewes fed on a low plane of nutrition; values were 8·8 and 8·3 % respectively. High plane ewes gave significantly more milk than low plane ewes. Ewes suckling twins gave significantly more milk than those suckling singles. Lambs suckling high plane ewes gained significantly more weight than those suckling low plane ewes both from birth to 3 weeks as well as from birth to 12 weeks. Male lambs gained significantly more weight than females.

Highly significant correlation coefficients were obtained between milk consumed by the lamb and its gain in weight. Conversion efficiencies of milk to gain in weight were calculated and compared with literature values.

Results of 132 maize fertilizer experiments (NP and NPK) carried out over 3 years in Western Tanzania have been grouped to give sixteen ‘response areas’. Responses to N and P were very large in the south-western half of the research zone, where rainfall is fairly well distributed. On granitic soils around Lake Victoria, responses were mainly to N alone. In the drier areas, notably Shinyanga district, responses to both N and P were on average very small. No significant positive responses to K were found, except for one trial in Karagwe district.

It was found that all observed responses to N and P could be accounted for in terms of a generalized two-factor Mitscherlich-Baule yield equation, with constant curvature terms, cn and cv.

Using this equation it is possible to define ‘maximum economic requirements’ of the nutrients N and P for various maize and fertilizer prices and potential yields. The difference between this maximum requirement and the amounts of these nutrients supplied by the soil (given by the Mitscherlich-Baule parameters bn and bp',)represents the optimum rate of fertilizer application, where profit per acre is at a maximum.

Empirical equations are presented for estimating b from soil analysis results for areas not adequately covered by these experiments, but such estimates may not always be accurate.

Twelve Friesian heifers were given four dietary treatments from 2 months before first calving to the end of the first lactation. Two of the treatments involved the ad libitum feeding of a complete diet consisting of a basal concentrate meal of rolled barley with supplements, incorporated into a mixture with either hay or barley straw both coarsely ground and included at a level of 25 % of the complete mix. In the other two treatments either the hay or the straw was given ad libitum in the long form and the concentrate mix fed ad libitum from a separate self-feeder.

Full records were kept of the intake of food and water, the output and quality of the milk and of live weight. Detailed measurements were made of various aspects of rumen function using one cow on each treatment fitted with a cannula. Rumen samples were also obtained from non-fistulated cows by stomach tube.

The intake of long roughage, particularly straw, by the cow, when offered in conjunction with a separate supply of the concentrate mix, was very low and led to serious falls in milk butterfat content. Where the roughage was incorporated into the complete diet normal butterfat levels were maintained. However, apart from the depressed butterfat levels on the two long roughage treatments the health and condition of the cows remained good.

The very low intake of long straw was associated with a smaller volume of liquid in the rumen, a reduced rate of flow of liquid leaving the rumen, a lower proportion of acetic and butyric acids and a greater proportion of propionic acid in the rumen liquor and finally with a higher blood glucose content. The inclusion of milled roughage resulted in values within the normal range for volume of liquid in the rumen, flow rate of liquid from the rumen, V.F.A. proportions in the rumen liquor and blood glucose.

The intake of both food and water over the productive cycle showed a consistent pattern for all cows. Food intake reached its lowest point around calving followed by a sharp rise to a peak in the 4th month after calving and then a gradual but increasing decline. Water intake followed a similar pattern but the fluctuation was greater and the peak consumption occurred in the 3rd month of lactation. Water intake was more closely associated with D.M. intake than with milk output.

The efficiency of utilization of the complete diets containing the milled roughages is discussed in relation to comparable data from cattle fed conventionally.