1. Embryonic mortality and reproductive performance were studied in 150 mature Merino ewes, groups of which were restricted to approximately 15% of their maintenance requirement from days 0to7 (group 1), 6to13 (group 3) and 13to20 (group 4) respectively. Groups 2and5 were controls. Ovulation point counts, returns to service, pregnancy test by laparotomy at day 40 and lambing performance were used to assess and apportion the embryonic loss.

1. Frequent soil sampling to 10 ft. depth was carried out on irrigated and unirrigated plots and, with the assistance of rainfall data, fairly accurate measurements of water uso were obtained unless the soil was at, or near to, field capacity. Evapotranspiration could then not bo distinguished from drainage beyond the root range.

2. A previous method of relating the water uso of unirrigated coffee to the readings of a sunken evaporation pan was shown to be reliable. The relationships between the water use of unirrigated coffee and meteorological factors (Penman's Eo, sunken pan evaporation or solar radiation) were shown to be dependent on soil-moisturo deficit, and on this basis a more precise method of predicting water use from sunken pan evaporation is proposed. When this method was applied to meteorological data from earlier years, good agreement was obtained between measured and estimated quantities of water in a 10 ft. profile.

Oats grown in a pot experiment on two sandy loams were sampled at four stages of growth. Neither KC1 nor MgSO4.7H2O had any effect on yield but % Mg and total Mg uptake were consistently decreased by applying K and increased by applying Mg.Ca(NO3)2 increased % Mg more than did (NH4)2SO4, but yield and total Mg uptake were higher where (NH4)2SO4 was applied. The effects of fertilizers were similar on both soils.

The effects of applying (NH4)2SO4 and NaNO3 to the soil on % Mg in barley were compared in a field experiment on an acid loam to which several rates of limestone had been applied. Treatments had no effect on the % Mg in grain or straw at maturity. At four earlier stages of growth (NH4)2SO4 increased % Mg in the plants more than did NaNO3. Limestone slightly increased % Mg. Nitrification of NH4 in the soil was rapid.

A study has been made of the effect of a progressive increase in the hours of light each day on the sexual activity of German Merino, Persian Blackhead and indigenous ‘Native’ ewes.

Incidence of oestrous tended to be greater in ewes subjected to extended daylight than in ewes subjected to the natural photoperiod. This was particularly true during the latter stages of the study. Duration of oestrus was unaffected by the extended daylight but varied temporarily in both groups of ewes. The effect of extended daylight on duration of the oestrous cycle and on the incidence of oestrous cycles of normal or abnormal duration was not marked and differed between breeds. Extension of daylight to 19 hr. each day apparently did not prevent reproduction since several light-treated ewes inadvertently conceived, gave birth to and reared a healthy lamb after a gestation period of normal length.

1. Balance experiments, in which urine was collected by a catheter inserted into the bladder, were carried out on four lactating ewes on two diets of fresh spring herbage and on one of hay plus cake, and the metabolism of magnesium, calcium, phosphorus, potassium and sodium were studied.

1. An experiment was carried out in 1961 and 1962 to test the effect of the application of high levels of fertilizer N to S 23 ryegrass swards on the health and performance of grazing calves. A uniform application of 47 kg. P and 75 kg. K/ha. was used in each year. Nitro-chalk was applied at monthly intervals from February to September, at rates equivalent to 22.4 kg. (Nl) and 112 kg. (N3) per hectare in 1961; in 1962 an intermediate rate (N2) of 67.2 kg./ha./month was also used. The total quantities of N applied per hectare in 1961 were 185 and 1042 kg. and in 1962, 192, 576 and 961 kg.

2. Male calves, 2-6 months old when introduced to the experiment, grazed in rotation round a series of four paddocks on each treatment. In 1961 Friesian, Aberdeen Angus cross and Shorthorn twin calves were used; in 1962 all the calves were unrelated Friesians.

Eight flushing experiments were conducted with grazing sheep over a 4-year period, the responses being measured at lambing. In the first 2 years mobs of 600-750 ewes were employed. Those experiments were designed to separate, identify and measure the two components postulated as comprising the flushing response—a static live-weight effect not specifically related in time to the mating period, and a dynamic effect of the rising or falling body condition which is specific to the mating period.

1. The object of the experiment was to determine the effects of varying the quantities of herbage available to cows on their diet and milk production.

2. Four groups of five Ayrshire cows were strip grazed for three periods of 3-4 weeks on areas calculated from sample cuts to supply (A) 25, (B) 35, (C) 45 or (D) 55 lb. dry matter per cow per day. These periods were interspersed between four standard periods of 2-3 weeks, in which all the cows were strip grazed on 50-60 lb. dry matter per head per day.

3. Measurements of milk production and of herbage consumption, by the chromic oxide-faecal nitrogen technique, were made for the last 12 or 16 days of experimental and last 8 days of standard periods. The observations made in the standard periods were used as covariates in the analyses of those made in the experimental periods.

The Awassi flock raised at the Abu-Ghraib Experiment Station over the years 1960-64 produced 923 single and 88 twin births. The environmental factors affecting birth weight, and the repeatability of birth weight were investigated.

Sex of lamb, type of birth, weight of dam, time and year of lambing were found to have significant effects on the birth weight of Awassi lambs. Male and single lambs were heavier at birth than female and twin lambs respectively. Ewes weighing between 126 and 135 lb. produced the heaviest lambs at birth. Lambs born earlier and later in the lambing season were heavier than lambs dropped in midseason.

Variations in the time of onset of the breeding season in Clun ewes have been studied during the four years 1962-65. Differences within seasons were studied in 1963 and 1964 by scattering the lambing over the first 7 months of the year. The date of first service then appears to be very highly dependent on the date of previous lambing. Time of previous weaning appears to be less important.

Very highly significant differences have been found between seasonal means and these differences have been shown to be significantly related to the mean ambient temperature during a limited period between mid-summer and the mean date for the resumption of cyclic activity in the ewes. The higher this temperature the later the onset of breeding activity. Over the years individual ewes have tended to breed consistently either early or late.

Nine Cheviot and nine ¾ Merino, ¼ Cheviot sheep were fed at similar annual maintenance levels. The annual ration was provided in three ways–in simulation of the ‘natural’ intake cycle, the reversed intake cycle or as a constant daily ration. Liveweight curves for both breeds corresponded fairly closely with the feed intake curves but considerable genotype/environment interaction was found in the response of unscoured wool growth to variation in feed intake.

After an extended period of adjustment, the between sheep variation in intake, in the Merino group, was reflected in variation in wool-growth rate at all times. In the Cheviot group, intake and wool growth were related in summer but not in winter. It is suggested that not only is the efficiency of wool growth subject to genetic control but that the modification of efficiency in response to variation in environmentally controlled metabolic processes is also a function of the genetic background.

1. Diallel crosses between six inbred lines of winter beans, the selfed parent lines and two commercial varieties were grown in a field trial in two years and records made of yield, number of steins, podded nodes, pods, weight of seed, plant height and width and flowering date. From these data four quotients representing components of yield were obtained.

Behaviour of lambs was studied in three separate physiological states resulting from planned exposure to cold, i.e. energy reserves depleted, discomfort during the experience of cold, and hypothermia.

When lambs were observed under mild conditions, prior depletion of about 20 % of the energy reserves, due to exposure to cold conditions for 4 hr., was without marked effect on teat-seeking activity. However, when the lambs were observed under cold, wet conditions, there was a marked depression of this activity. The activity in lambs which had been kept warm to conserve energy also tended to be depressed under conditions of discomfort due to cold.

1. The potassium, sodium, calcium, magnesium and phosphorus contents of the grass and clover fractions of a perennial rye-grass and white clover sward were determined at each of five cuts taken between May and October in 1962 and 1963.

1. Sorghum is capable of giving substantial yields under dry conditions where maize fails.

2. Sorghum can consistently out-yield maize in some areas under conditions of apparently adequate or excessive rainfall.

3. Low soil nutrient status, and/or poor soil water relations, interacting with the amount of rainfall were probably responsible for the low maize yields where precipitation in the growing season exceeded 15 in.

4. Some hybrids originating in the U.S.A. may be of immediate value in dry areas of East Africa. Such hybrids are generally susceptible to bird damage and are more susceptible to Atherigona indica infuscate than local material. Hazera 726 shows less susceptibility to both these pests and is recommended for dry areas.

1. Experiments were carried out in 1961 and 1962 to study the effect of high levels of nitrogenous fertilizer on the health and performance of early weaned lambs. The lambs were artificially reared and grazed in a ‘worm-free’ area. In 1961, levels of Nitro-chalk were applied at 22 and 110 kg. N/hectare/month and in 1962 an intermediate level of 66 kg. N/hectare/month was added; the actual totals applied per hectare were 220,660 and 1100 kg. to treatments N1, N2 and N3 respectively. All nitrogen treatments were carried out with and without irrigation (applied to maintain a soil moisture deficit of less than 2.5 cm.).

2. Lambs were introduced to the experimental plots when 8-10 weeks of age and grazed in rotation a series of four paddocks on each treatment; a low grazing pressure was maintained at all times.

Skin thickness was measured in Sahiwal and Jersey cows in early spring and early summer.

Differences between breeds were significant at each season, Sahiwals always having the thickest skins. Seasonal variation in skin thickness was also significant, animals of both breeds having thicker skins in early spring than early summer. No relationship was apparent between body weight and skin thickness.

1. A study of the suitability of rations of predominately sorghum grain for the intensive finishing of steers is reported. Six groups, each of ten steers, 18 months old and of an average body-weight of 544 lb., were fed, according to a set schedule, increasing quantities of grain in the ration until two groups were each consuming rations containing 80, 90 or 100% grain. One of the two groups, fed each grain-to-roughage ratio, received 60 g. urea per head daily. Individual steers were slaughtered when they attained 900 lb. body-weight. A seventh group of ten comparable steers was slaughtered at the commencement of feeding in order to measure changes in body composition due to the nutritional treatments.

A co-ordinated trial has been carried out with fattening pigs at nineteen centres to compare the effects of the following methods of preparing and presenting the feed: (1) meal fed in the trough; (2) cubes fed in the trough; (3) meal fed off the floor; (4) cubes fed off the floor.

Pigs fed meal off the floor had substantially worse growth rate and feed conversion than pigs on any of the other three treatments, probably because of feed wastage. With trough feeding, pigs fed cubes had slightly better growth rate and feed conversion than pigs fed meal. When the feed was given as cubes, there was little to choose between trough feeding and feeding off the floor. Faster growing pigs were slightly fatter and had slightly smaller eye muscles.

1. A method of conducting accurate walking trials with small numbers of cattle is described. Using the method, a comparative study has been made of the walking abilities of Hereford and Santa Gertrudis heifers during exposure to moderate heat stress in the field. During any one day, animals were subjected to enforced exercise for four sessions of 1 hr. each between 10 a.m. and 3 p.m. at either 1⅔ or 2⅔ m.p.h.