The 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.

Eight 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.

The 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%.

Results 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.

The 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.

Flocks of 9-month-old Merino and Border Leicester & Merino sheep were sampled over the full range of body weights present within flocks. Six pairs of ewes and wethers of equal body weight were taken. The sheep were weighed and slaughtered after a 36 h fast. Total weights of blood, skin, head, feet, internal organs and carcasses were obtained for each animal. Each component was analysed for ash, crude protein, ether extract and total energy. Half of each carcass was dissected into bone, muscle, fat and waste.

The compositions of the sheep were compared by regression analyses of weights of body components on empty body weight (EBW) between the four groups and by means of percentages of EBW. There were highly significant linear relationships between both fresh and dry weights of body components, carcass components, and chemical components with EBW; moisture content was not related to EBW. Rates of change with EBW in weights of body components, or in amounts of ash, crude protein, ether extract and energy were the same for all groups of sheep with the exceptions of bone and skin ether extract (EE) weight. However, intercepts of regression lines frequently differed, indicating that body composition differed between groups at the same EBW.

All groups had the same dry weight of blood, internal organs and muscle, weight of ether extract, and total energy in the whole body at the same EBW. Border Leicester × Merinos had lighter skins with less wool, but their carcass weights were higher than Merinos. There were other differences between breeds in the chemical composition of individual components. Wethers had heavier head + feet weights and carcass bone than had ewes. There were also some sex differences in chemical composition of body components. In general, there were fewer sex than breed differences in body composition. The breed differences cannot be explained on the basis of early and later maturing types.

Empty 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.

Three 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.

The concentration of copper in the blood of more than 300 sheep of a grassland flock was determined on each of five occasions between May 1965 and June 1966. Six breed classes, Scottish Blackface, Cheviot and Welsh Mountain, and the three crosses among these breeds, were involved.

Breeds differed significantly in blood copper concentration with the Blackface having consistently the lowest and the Welsh the highest values. Crossbred sheep showed marked heterosis. Their levels were mostly at or near to the concentration of the parental breed with the higher value. Within breeds there was a positive regression of blood copper level on live weight of ewe.

Ewes which had produced lambs affected by swayback in 1964 had lower levels of copper in their blood than ewes which had produced normal lambs. The difference was significant and most marked in winter.

Ewes which were barren had, subsequently, higher blood copper concentrations than ewes with lambs. Ewes with single lambs had on average slightly higher levels than those with twins (but not significantly so), however, the effect differed among the breeds. Blood copper levels differed significantly on most occasions with the week in which ewes lambed in relation to the date of bleeding. Age of ewe had significant effects on copper concentration only at one bleeding (January 1966).

There was an indication that classes low in copper concentration, notably Blackfaces and mothers of swayback lambs, showed a relatively steeper decline in copper levels during the winter than did other sheep.

Milk yield data obtained by the lamb-suckling technique on twenty-four ewes over a period of 5 consecutive days in the second and third week of their lactation have been related to lamb body weights and lamb body-weight changes over the same period. The regression equation obtained was

The equation was used to estimate the milk consumption of lambs over the range of lamb body weights and lamb body-weight changes studied. The standard errors of these estimates have been computed for comparison with those obtained directly from the lamb suckling technique.

The role of the prediction equation in estimating daily milk consumption of lambs is discussed.

Two 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.

Twenty-seven ewes in various states of fatness, and either non-pregnant or between 72 and 144 days pregnant, were slaughtered and the volumes of digesta and abdominal organs were measured. There was a significant negative relationship between the volume of rumen contents and the volume of uterus plus abdominal fat plus other abdominal organs.

A radiographic study was made of the skeleton of eighty-three foetuses from twenty-four litters killed between the 37th and 112th day of gestation. Measurements were taken, from radiographs, of the length and depth of the skull and the length of the diaphyses of the humerus, radius, ulna, metacarpus, ilium, ischium, femur, tibia, fibula, calcaneum and metatarsus. Skull length, humerus and metatarsus were selected for statistical analysis. The litter mean lengths of the diaphyses were studied in relation to age, weight, and age and weight jointly. Within-litter differences in bone measure-ments were closely associated with foetal weight differences.

The relationships of litter mean log. lengths of the skull, humerus and metatarsus upon age were best fitted by a quadratic regression, and with mean log. foetal weight by linear function regressions. A joint regression incorporating both age and weight of the foetuses fitted the data significantly better than equations based on weight or age alone. Skull length was found to have a growth coefficient between the 51st and 112th day of gestation significantly lower than that of the other bones examined. The age at which the primary and secondary ossification centres appear was studied.

The 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.

The body composition of eight Merino wethers was estimated from the tritiated water (TOH) space and live weight at intervals during a cross-over experiment in which they were fed to either maintain a uniform live weight (about 34 kg) or to lose and, later, recover live weight over a 17-week period. The diet was a pelleted mixture of lucerne and wheat.

The multiple regression equations used for these estimates were established from the chemical analysis of 24 sheep, including six from the cross-over experiment, which were killed at intervals during these two feeding regimens. The inclusion of TOH space in addition to live weight in the regression equations decreased the standard error of the estimates of body water, fat and energy by two-thirds. Correction of TOH space and live weight for gut water did not increase the precision of the equations.

Shoop which ate, during the first 4 weeks of the experiment, one-third of the amount of food required to maintain their original live weight, lost 16% of their weight and 30% of their total body energy. This weight loss consisted of 45% water, 39% fat and 13% protein. It appeared that tissue was mobilized inefficiently to meet a sudden energy deficit.

When food was offered ad lib. to these sheep after they had maintained a liveweight deficit of about 11 kg for 8 weeks, they regained their weight in 5 weeks but only 75% of their energy deficit. This was due to the high content of water (60%) and low content of fat (23%) in the regained tissue.

The sheep that lost weight and then recovered it were, over-all, about 86% as efficient in their use of food to maintain body energy and produce wool as the sheep that maintained their original weight.

A quantitative evaluation of the pigment in Murrah buffaloes of both sexes ranging in age from 1½ to 7 years revealed that dorsal areas had most pigment, while the lateral body areas and the extremities were intermediate and the ventral and axillary regions revealed the least pigment. Maximum concentration of melanin granules occurred in stratum cylindricum, which gradually declined towards stratum corneum which was fully non-pigmented in axilla, groin, inter-digital and inter-dewclaw areas.

Pigment granules blackened in silver preparations and were seen concentrated as protective ‘nuclear caps’ in the supranuclear zone of the cells of stratum germinativum. The infranuclear light-staining cytoplasm contained PAS reactive glycogen granules.

The 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.