1. The yield and composition of milk from twenty Border Leicester x Cheviot ewes offered dried grass cubes, dried grass cubes and hay, hay or grazing was determined over a lactation period lasting 10 weeks. Milk yield was estimated by weighing the lambs before and after each suckling on one day each week. Samples of milk for analysis were obtained at fortnightly intervals by hand milking the left side of each udder before the mid-day suckling by the lambs.

2. Ewes receiving dried grass cubes and suckling twins and those receiving dried grass cubes and hay reached mean peak milk yields of 3470 and 2680 g./day, respectively, at 2-3 weeks after parturition, whilst the yields of the remaining ewes declined continuously from the beginning of lactation. The mean milk yield over the lactation of ewes receiving dried grass cubes and suckling twins was 2785 g./day, of those receiving dried grass cubes and suckling singles 1821 g./day, of those receiving dried grass cubes and hay 2119 g./day and of those receiving hay 1177 g./day. The yield of milk energy was highest for all ewes during the first week after parturition.

In an experiment to investigate the interrelationships of genetics and nutrition in the growth of cattle up to 2 years of age, five monozygotic and six dizygotic Ayrshire twin heifers were reared under close nutritional control on an all cubed diet.

Two control systems were used. Some animals were fed similar amounts of food, and differences in growth rate and efficiency examined while others were made to grow alike and differences in food consumption and efficiency examined. Overall, similarly fed animals had similar growth rates and efficiencies and similarly grown animals similar food intakes and efficiencies. Variation in growth, food consumption and efficiency was much less than in an ad lib. feeding system.

1. The intake of grazing wethers was estimated from the in vitro organic matter digestibility of herbage samples collected from sheep with oesophageal fistulae, and total faecal collections.

2. Body water, estimated by isotope dilution, was used to estimate total body energy from estab-lished regressions relating body water to body composition.

3. Total body energy was then related to live weight by regression analysis, giving a value of 2044 kcal. per lb. over the range 68-90 lb. empty body weight. From this it was estimated that 2.41 lb. D.O.M. was required per lb. live-weight gain within this range.

4. Energy for maintenance was calculated by deducting D.O.M. required for gain from D.O.M. intake. These values were related to live weight by regression analysis to give a value of 1.31 lb. D.O.M./day for the maintenance of a 100 lb. sheep.

The primary growth of eight varieties of three species–white clover (3), red clover (4) and lucerne (1)–was sampled at fortnightly intervals and the percentage dry matter, in vitro digestibility, crude protein, water soluble carbohydrates, P, Ca, K, Na and Mg were determined.

Differences between species were nearly always significant and the general order of merit was white clover, red clover and lucerne. The exceptions were for dry-matter percentage where this order was reversed, and red clover had the lowest Na and highest Mg content.

1. The effects of age of ewe, and year, sex and type of birth of lambs on lamb weights between birth and weaning were measured and appropriate correction factors estimated in a flock of East African Blackheaded sheep maintained over an 11-year period in Western Uganda. These correction factors were then used to examine the effects of a long dry season at different stages of lamb growth.

2. On birth weights the effects of sex ranged from 0-25 lb. to 0-40 lb.; twinning 1-0 lb.; gimmer's lamb 0-5 lb. On 2-month weights the corresponding adjustments were 0-2 lb.-l-4 lb.; 5-1 lb.; 1-7 lb. On weaning weights 0-3 lb.-2-9 lb.; 6-0 lb.; 2-6 lb.

3. A long dry season during late pregnancy did not appear to affect lamb birth-weights and a dry season between 2 months and 5 months of age did not affect lamb weaning weights. However a dry season during the main suckling period from birth to 2 months of age significantly lowered lamb weights at 2 months of age.

1. Male-sterile plants were discovered in the progeny of an open-pollinated plant which had undergone a much higher level of natural crossing than any of a group of fifty plants drawn from the same population.

2. Some male-sterile plants produced a few viable pollen grains under some conditions but these rarely permitted self-fertilization. A few plants had both sterile and fertile tillers. Male sterility was not transferred by grafting. No effect on the proportion of fertile plants could be found, when progenies were observed early and late in the season, sown in the autumn and spring or grown at contrasting plant densities.

3. Inbred lines, unrelated to the male-sterile plants and their derivatives, varied greatly in their ability to restore male fertility. Some lines maintained the sterility almost completely, two consistently gave all male-fertile offspring, but the majority were partial restorers.

1. The feed intake of four dry and of twenty pregnant and lactating ewes has been measured. Hay and dried grass cubes alone or in combination were studied on indoor conditions by direct measurement of intake and digestibility while the intake on grazing was measured by the chromic oxide-faecal nitrogen method.

2. For dry sheep, hay (61% O.M. digestibility) limited intake to 780 g. D.O.M./day and with added grass cubes there was a steady increase so that intake with cubes alone (although their apparent O.M. digestibility was 56%) was 1140 g. B.O.M./day. Pregnant ewes showed similar intakes and only with ewes carrying twins and triplets was there a slight decline in intake with advancing pregnancy.

3. The digestibilities of the diets were similar for pregnant, and lactating ewes.

1. The mean daily live weight gains of lambs were used to estimate the milk production of ewes and gimmers during the first 8 weeks of lactation. Records of 1178 lambings of East African Blackheaded sheep between the years 1952 and 1962 were available.

2. Gimmers had significantly lower production than second and subsequent lamb ewes. Ewes rearing twins had a significantly higher yield than ewes rearing singles. There appeared to be no difference in yield between ewes producing twins but rearing singles, and ewes rearing natural singles.

3. A long dry season with resultant lowered plane of nutrition significantly reduced the live-weight gain of lambs.

1. A method of producing hybrid beans with the aid of a cytoplasmic male-sterile is described.

2. Most of the requirements of large scale production of hybrid seed can be met: use of genetic markers showed that the male sterility allowed 100% cross fertilization; there was no evidence of a deficiency of insect pollinators near Cambridge; and fertility restoring lines are available.

3. The importance of being able to maintain a high level of sterility in the female parent line is emphasized. Methods of improving the proportion of sterile plants in the sterile phase of an inbred are discussed. The tolerable level of fertility in progenies of sterile parents depends on the level of sterility necessary in the female parent of the final cross. Five inbreds are being handled with less than 2% of fertile plants in their sterile phase.

1. Seed plots of five perennial rye-grass varieties, S23, S24, S321, Melle Pasture and an experimental type, Ba6280, were established in 18 in. rows.

2. Each variety was subjected to hard grazing by sheep in September, at ear initiation in spring, and 3 weeks following ear initiation; one series of plots was left ungrazed. Three levels of spring nitrogen, 2, 4 and 6 cwt./acre ‘Nitro-chalk’ (21%N), were applied to subplots.

3. S321 produced significantly more seed heads and Ba6280 gave significantly fewer heads than S23, S24 and Melle. September grazing increased head production by 15%, whilst the two spring grazings gave fewer heads than the ungrazed plots. An increase in the rate of nitrogen application in spring favoured head production.

1. Four mature, fistulated Africander steers were used to study the effect of four different high concentrate diets on the concentration and rate of production of steam V.F.A., and on concentrations of certain constituents found in the blood, rumen digesta and urine of these animals. Each steer received each diet for 4 weeks in a Latin square design and samples of blood, rumen digesta and urine wore taken in the last week of each monthly period. The diets were based on maize grain with a protein-mineral-vitamin A supplement and contained varying proportions of roughage, namely, 0, 10, 20 and 30% of the quantity of concentrate.

1. A series of three field experiments, concerning the effects on growth, development and yield of sugar beet of extension of the growing season by transplantation, were carried out in 1962, 1963 and 1964. The first two experiments were subject to sequential sampling programmes for growthanalysis purposes, but in the third only yield data were recorded.

2. Root yield increased with advance in planting date and increase in plant population in all 3 years. Nitrogen had no effect on root yield in any year. There was no consistent interaction between time of planting and plant population in their effects on root yield. The advantage for transplanting over field sowing ranged from 4 tons washed beet per acre in the case of an early field sowing (20 March) to 10 tons in a late one (23 April). There were no treatment effects on the concentration of sugar in the roots. The roots of transplants were more globular in shape and fanged than were those of field-sown beet.

1. The effects of birth weight, sex, twinning, parity of dam and dry season on mortality rates of lambs were studied between birth and weaning at 20 weeks in a flock of East African Blackheaded sheep.

2. The mean birth weights of non-surviving lambs were lower than those of surviving lambs. Singles from gimmers and twins from ewes were 0.5 and 1.0 lb., respectively, lighter at birth, and had higher mortality rates than singles from ewes. The overall mortality rate of singles from ewes was 16%, singles from gimmers 20% and twins from ewes 28%. Male and female lambs born alive had similar mortality rates (18%).

1. The effects of cutting herbage to either 1 in. or 2½ in. from ground level were studied at varying cutting frequencies in two experiments on a perennial rye-grass/white-clover sward. In one of the experiments the frequency of cutting was decided by the stage of growth of the herbage, and in the other it was decided on a time basis where cutting was carried out at intervals of 2, 4 or 6 weeks throughout the growing season.

2. Greater yields of herbage dry matter were obtained by cutting to 1 in. rather than to 2½ in. at all cutting frequencies in both experiments. This effect did not vary significantly with frequency of cutting where cutting dates were decided by the stage of growth of the herbage. However, where the cutting frequency was decided on a time basis, close cutting gave a relatively greater yield increase compared with lax cutting where the herbage was cut every 2 weeks instead of every 4 or 6 weeks.

3. The results suggest that the practice of cutting at an average stage of growth in previous experiments probably had little or no influence on the effects recorded for the contrasting closeness of cutting treatments.

1. Growth and development in relation to yield were studied in the two maincrop varieties King Edward and Majestic in 1959 and 1960. The effects of seed size and spacing were also investigated.

2. The total tuber yield, and more particularly the ware yield, of Majestic was greater in both years. This was associated with a longer period of tuber bulking in this variety, due, in 1959, to earlier tuber initiation, and in 1960, to earlier tuber initiation and greater persistence of tuber bulking. Large seed outyielded small seed, although the difference, particularly in ware yield, was relatively small. The seed size effect was associated with a difference in the length of the bulking period, in consequence of a difference in the time of tuber initiation. Total yield tended to increase with decrease in spacing distance; ware yield increased as spacing distance decreased from 24 to 18 in., but there was little difference between 12 and 18 in. spacing. In general, low seed rates performed better than might be expected.

1. The metabolism of 137Cs in dairy cows has been studied after single oral and intravenous doses and during twice daily oral dosing for 28 days.

2. Gastrointestinal absorption of 137Cs was about 70-80% of the oral doses.

3. After 28 days continuous feeding the mean concentration of 137Cs in milk was 0.84% daily dose/1. and the body burden of the isotope varied between 5.7 and 8.2 times the daily intake.

4. When feeding of 137Cs stopped the concentration of the isotope in milk fell by a factor of five in 8 days, by a factor of ten in 16 days, by a factor of twenty in 32 days, and thereafter exponentially with a half-life of 30 days. The concentrations of the isotope in muscle decreased at first rather slowly but finally also exponentially with a half-life of approximately 30 days.

1. Broad bean plants caged with bees produced more seeds per pod, more seeds per plant, heavier seeds and a greater weight of seeds per plant than plants caged without bees. They also had more mature pods at the first harvest but the total number of pods picked was about the same for cages with and without bees. The flowering season of plants caged without bees was extended.

2. Field bean plants caged with bees had more seeds per pod and more seeds per plant than plants without bees.

3. For both crops, plants in the open had about double the number of pods, beans and weight of beans as plants in cages.

1. A factori al experiment involving four varieties (Ulster Chieftain, Arran Pilot, Craig's Royal and Ulster Torch) and three times of planting (28 March, 13 April and 2 May) was undertaken with a view to investigating the effects on growth development and yield of these factors. Only a limited amount of data was obtained in respect of Craig's Royal, because of its extreme variability in the first two times of planting. In addition, data in respect of King Edward and Majestic planted on the second date in an adjacent experiment are discussed.

2. In general, yields from Ulster Torch were about twice as great as those from Ulster Chieftain, with the other varieties occupying intermediate positions. The total yield of Ulster Chieftain increased with delay in planting, while in Arran Pilot, Craig's Royal and Ulster Torch, yield was greatest at the intermediate planting date, slightly lower than this at the first, and lowest at the third. Ware yield as a proportion of the total increased with delay in planting.

1. In a grazing trial with sheep, cocksfoot, ryegrass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems, and also white clover.

2. Live weights were recorded every 2-3 weeks, and wool production was estimated by clipping midside patches every month.

3. Sheep on grass plus clover plots were significantly superior to sheep on grass plots in terms of live-weight gain, final live weight and clean-wool production.

4. Sheep on ‘long’ pastures were significantly heavier than sheep on ‘short’ pastures for a month in the early part of the trial. Thereafter, differences in live weight were not significant.

1. In a grazing experiment with sheep, cocksfoot, rye-grass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems.

2. One sheep on each plot was fitted with an oesophageal fistula, from which herbage samples were collected at fortnightly intervals. The botanical composition of samples from the mixed swards was estimated by an optical point quadrat method. Samples were analysed for crude protein and cellulose, and digestibility was estimated in vitro.

3. Treatment difference within the mixed swards were not significant in terms of botanical composition. The mean proportions selected were 73% grass, 9% clover and 18% dead matter. The proportion of clover selected did not differ significantly between sample collections.