Twenty-one Finnish Landrace × Polled Dorset Horn female sheep approximating 8 months old were individually penned from 3 to 4 weeks after mating until parturition. They were allocated to one of three diets containing either 12·3, 14·1 or 16·5% crude protein and 2·1 Meal metabolizable energy per kg dry matter, offered at a level of 85 g/kg W0·75 per day. A series of nitrogen balance trials was carried out on all lambs during the last 100 days of gestation.

The mean age at parturition was 382 days and the mean litter size 1·52. The live-weight gain (mean value 152 g/day) was not significantly affected by the level of protein intake. There was a tendency (005 < P < 0·10 for singletons) for lamb birth weight to decrease and the body-weight change of the dam to increase with increasing protein concentration in the diet. There was a significant linear increase in nitrogen retention both with stage of gestation and level of protein intake.

The partition of nitrogen between the foetal and maternal body is discussed in relation to the estimated nitrogen content of the maternal live-weight gain.

The wool growth cycle in three rams and three ewes was studied by taking monthly wool and skin samples for periods up to 3 years. The percentage of inactive follicles and of medullated fibres was recorded, fleece length was measured and change in fibre diameter and pigmentation between summer and winter was investigated.

Casting of the fleece appeared to depend more on the thinning of fibres than on the proportion with brush ends, casting in some instances taking place with only 30% brush ends, while not in others with as much as 70% follicle inactivity.

Follicles began to become inactive in both sexes in September following the autumnal equinox. The secondary follicles had a greater proportion of inactivity (mean of 45% compared with 20% in the primaries) but tended to regrow earlier, and regrowth in the rams tended to begin before that in the ewes. Regrowth as a whole began from January to March. Subsidiary cycles of inactivity of about 2 months' duration were evident.

Maximum growth in length occurred between April and October. A difference in mean diameter of only a few microns could be detected between summer and winter. Maximum medullation occurred in July in the rams and August in the ewes. Decrease in pigmentation in winter was brought about by a lowering of the density of pigment granules within the fibres.

1. The metabolic rates of 58 individual piglets kept either on a straw or on a concrete floor at ambient temperatures near to 10°, 20° or 30°C have been measured with ages ranging from newborn to 9 days, and body weight from 1·0 to 3·2 kg. The oxygen consumption was measured on each floor material at the chosen ambient temperature thus allowing paired comparisons for each animal.

2. In comparison with the concrete floor, oxygen consumption on straw was reduced by 18% at 10°C, 27% at 20°C and by 12% at 30°C for pigs 2 to 9 days old. The regression coefficients of mean log (oxygen consumption) on log (body weight) were around 0·66 at 10° and 20°C. At 30°C the value was 0·99 ± 0·14. The regression coefficients were not significantly affected by the presence of a straw floor showing that its effect did not vary with body weight. Corresponding values foi piglets below 24 hours of age were 17% at 10°C, 27% at 20°C and 22% at 30°C ambient temperature.

3. Moving a piglet on to a straw floor at 10°C had the same thermal effect as raising the ambient temperature to 18°C. Similar treatment at 30°C was equivalent to raising the ambient temperature to 32°C.

4. Lowering ambient temperature to increase the temperature gradient between the homeothermic body of the piglet and the environment progressively increased heat loss in all cases. There was a concomitant decrease in the calculated conductance between core and environment which was more pronounced for the piglets lying on the concrete floor.

1. A growth trial was carried out using 24 British Friesian steers given diets containing (1) 100%, (2) 60%, (3) 40% and (4) 0% concentrates and chopped dried grass up to 100%.

2. Daily dry-matter intake was significantly lower for steers on Treatment 1 than for steers on the other three treatments.

3. Rate of live-weight gain declined from 1·18 to 0·88 kg/day and carcass gain from 625 to 430 g/day between steers on Treatments 1 and 4.

4. Killing-out percentage dropped from 55·3% (1) to 51·9% (4) and the 8th-10th rib from steers on Treatments 3 and 4 contained significantly more crude protein and less ether-extractable matter than ribs from steers on Treatments 1 and 2.

Eight Merino wethers were used in an experiment designed to study the effect of heat stress on ruminal activity and blood urea of sheep newly introduced to Egypt. The sheep were exposed to 15° and 35°Cin aclimatic chamberwith controlled temperature and humidity. The animals were divided into two groups; the first received 100% of the TDN daily requirement and the second was given 125% of the recommended TDN. Rumen and blood samples were obtained from the animals before and at 2, 4, 6, 8 and 10 hr after feeding.

VFA concentrations in the rumen were higher in sheep fed on rations of high energy content. The levels of VFA at the low temperature were greater than at the high temperature. Ruminal ammonia and blood urea N concentrations in sheep maintained at the low temperature (15°C) were higher than those of the same animals when kept at the high temperature (35°C). This trend was more obvious at high levels of energy intake. It is suggested that the significant changes in rumen VFA, ammonia N and blood urea N in Merino sheep maintained under hot conditions can be considered as adjustments to changes in nutritional requirements in response to high environmental temperature.

1. Effects of late pregnancy and early lactation on the voluntary intake of dried grass (Expt 1) and a poor quality seeds hay (Expt 2) by dairy cows are described. Each cow received a constant daily allocation of concentrates throughout late pregnancy. After calving half the cows received an 80% increase in concentrates, and the remainder continued to receive their pre-partum allowance.

2. Mean daily intakes of dried grass were higher than those of poor quality seeds hay. Intake of dried grass in week 2 of lactation was significantly correlated with the live weight of the cows, but a non-significant correlation was observed when seeds hay was offered.

3. During late pregnancy mean daily intakes of both roughages were approximately constant until the week immediately before par turition, when a significant decline occurred.

4. After calving mean daily intakes of both roughages increased throughout the first six weeks of lactation by 20–30% of the intake at week 1 post partum.

5. The 80% increase in daily concentrate allocation in early lactation caused a significant decline of 0·55 kg dried grass dry-matter intake per kg concentrate dry matter; the decline of 0·17 kg poor quality hay dry matter per kg concentrate dry matter was not significant.

An implantation technique utilizing slow-release selenium pellets was evaluated as a means of controlling nutritional muscular dystrophy (NMD) in sheep. Sixty ewes were fed a dystrophy-producing hay and implantations were made at mid-pregnancy (14 animals) and in late pregnancy (15 animals); the remainder were kept as controls. Selenium was determined at intervals on milk and blood samples from the ewes and on blood samples from the lambs. Various muscles were examined histologically for NMD lesions.

Selenium levels in the milk of implanted ewes were higher than controls up to the 60th day of lactation and levels in the blood of both ewes and lambs were higher than controls during nursing. Selenium implantation at mid-pregnancy resulted in higher selenium concentrations in lamb's blood at birth than implantation in late pregnancy. However, by 30 days of age and thereafter, this difference was reversed. Large variability was encountered in the blood values for implanted ewes and their lambs. While complete protection against NMD was not achieved, implantation reduced the incidence and severity of the disease. The earlier implantation gave slightly fewer deaths from NMD, but the numbers were too small to make critical comparisons.

1. Two experiments have been carried out to determine the effect of a high air temperature, 32·33°C, on growth and backfat depth of pigs, by comparison with a thermo-neutral air temperature, 22·24°C. The diet consisted predominantly of whey, since it was expected thatthis would enable appetite to be maintained at the higher temperature.

2. Food intake was reduced by 5% to 7% during the period of exposure to 32°C in Experiments 1 and 2 respectively. Growth rate and FCE were reduced significantly only in Experiment 2.

3. Backfat depths measured above the eye muscle were significantly increased by the hot treatment in both experiments; those measured on the split carcass were consistently greater for the hot treatment.

Two groups of 24 Landrace × Large White gilts were allocated at puberty to two feeding regimes during oestrus. The control group received 1·8 kg food/day throughout the oestrus period, while the flushed group had an additional 1·8 kg immediately after mating on the first day of oestrus. The treatments were imposed at the first post-puberal heat (second heat) and at the post-weaning oestrus in the second and third parities. The sows remained on the same treatment throughout the experiment. Litter performance was measured in the first two parities. The sows were slaughtered on day 25 of their third gestation to provide data on ovulation rate and embryo mortality. Increasing feed intake to 3·6 kg on the day of mating did not significantly affect the number of piglets born, number born live, or mean piglet weight, in either the first or second parity. In the third parity, ovulation rate, embryo number at 25 days of gestation and embryo mortality were unaffected by treatment.

Three trials, each involving 24 pigs, were conducted to assess the value of Hormonexa as a feed supplement for pigs slaughtered at 90 kg live weight. Rations were compounded from a variety of feeding stuffs to different protein levels and the pigs were fed on various nutritional planes. Hormonexa was added to these rations at the rate of 1·32 kg per 1000 kg meal.

In all three trials growth rate and food conversion efficiency were not affected significantly by the addition of the supplement. There was a tendency for the pigs receiving the supplement to be slightly leaner but in only 1 out of 39 measurements of fat thickness was the difference between control and supplemented pigs statistically significant (P< 0·05).

No benefit from this feed supplement has been demonstrated in terms of animal performance or carcass quality under a range of feeding systems.

Eighty-two Merino sheep from birth to 517 days old were dissected into individual muscles. A system of overlapping growth coefficients was used to classify the growth patterns of 96 muscles and nine muscle groups. The relative size of muscles and groups at birth and one year are expressed as percentages of total half-carcass muscle weight.

Some differences were noted from the previously recorded growth patterns of bovine muscles. The groups of muscles in the proximal part of the pelvic limb and those surrounding the spinal column were relatively faster-growing in sheep than in cattle.

The patterns of the muscle groups are discussed relative to their function and it is shown that the patterns of growth of muscles within some groups are markedly different from the pattern of the whole group. This is most apparent in those groups with complex functions, and it is clear that anatomical grouping of muscles and functional grouping of muscles will be similar only in those regions of the body with relatively simple actions.

Results are given of an experiment in which 61 cyclic Finnish Landrace × Dorset Horn ewes were synchronized for oestrus by intravaginal treatment for 14 days using sponges impregnated with 30 mg ‘Cronolone’ (9a-fluro-11-hydroxy-17a-acetoxy-progesterone; SC-9880, G. D. Searle) and 400 mg progesterone. Groups of 31 and 30 sheep were inseminated twice, either artificially or naturally, at predetermined intervals of 48 and 58 hr after sponge withdrawal. All 61 ewes were in oestrus within 48 hr of removing sponges; 26 of 30 (87%) artificially inseminated and 29 of 31 (94%) hand-mated sheep conceived at the controlled oestrus. The incidence of multiple births was not significantly affected by the method of breeding.

Sixteen energy and N-balance trials with six sows were performed to study the energy requirement and protein gain of the animals during different stages in the second half of pregnancy. Energy and N-balances were measured during periods of 1 week and gaseous exchange was measured in a respiration chamber. The animals received 2·0,2·5,2·75 or 3 0 kg/day of a normal concentrate ration for sows. In one experiment, one animal had a negative energy balance on the 2 kg ration in the sixth week of pregnancy but in the other experiments the dietary energy intake was sufficient for positive energy balances until a few days before parturition. The N-balances were about 20 to 32 g/day in the second half of the gestation period. With 2·5 and 2·75 kg feed there was a negative deposition of fat at about 2 weeks before parturition. Heat production increased during pregnancy, but at a greater rate during the last 2 weeks. Until 2 to 3 weeks before parturition 2·5 to 2·75 kg of feed seemed to be adequate to meet the energy requirement of a pregnant sow of 180–200 kg live weight. During the last 2 weeks 3 kg was sufficient.

1. Forty Greyface (Border Leicester ♂ × Blackface ♀) and 40 North Country Cheviot ewes, due to lamb to a Suffolk ram in April 1969, were housed during December 1968 in eight groups of 10 ewes, the breeds being penned separately.

2. One pen of each breed received a basal diet of either hay, grass silage or arable silage with a ‘high’ level of concentrate supplementation and one pen of each breed was given hay with a ‘low’ level of concentrate supplementation. Within each pen, five of the 10 ewes were clipped at housing and the other five were clipped in the following June.

3. Voluntary intakes of the basal diets declined with advancing stage of pregnancy, particularly for those receiving grass silage. Feed had no differential effects on the performance of the ewes in terms of wool yield, body-weight change, birth weight of lamb per ewe or perinatal lamb mortality.

4. The Greyfaces clipped at housing yielded less wool than those Greyfaces clipped in the following June. Time of clipping had no influence on the wool yield of the Cheviots. Wool grades were not affected by time of clipping. Ewes clipped in December performed significantly better than ewes not clipped until June with a higher proportion of ewes producing multiple births (P<0·1), a higher total birth weight of lamb per ewe (P<0·01) and a reduced perinatal mortality of the lambs (P<0·05). The total effect of this improved performance was that the clipped ewes produced 53 ·5 % more live lambs than those ewes not clipped until the following June.

A total of 64 nine-week-old pigs were used in two experiments to study the influence on feed intake, growth and carcass quality of dietary restriction at various ages or live weights. Two diets of different energy content were given throughout each experiment, which was divided into four periods on either an age or weight basis. Feed was restricted or offered ad libitum during each of the first three periods, all pigs being fed ad libitum during the last period.

Compensatory intake following a period of feed restriction occurred at most stages of growth but was most marked in the early stages. Compensation when it occurred took several weeks to develop fully and persisted for some time, often after an intervening period of ad libitum feeding. Increased gains resulted from increased intake although some of the early compensatory gains could not be fully explained by increased intake.

There were few appreciable differences between the pigs on the highand those on the low-energy diets. However, in the early stages the latter did not show the same response in intake following restriction as did the former (but in experiment I the latter were considerably lighter).

No effects on carcass quality were demonstrated under the conditions of these experiments.

In a new ranching area of Uganda recently cleared of trypanosomiasis, with a high level of disease control, adequate water supplies and extensive grazing on free range, three dam breeds, the indigenous Ankole and Zebu, and the Boran from Kenya, were mated to Boran, Angus and Red Poll sires.

Under artificial insemination, at least 10 % fewer cows were detected on heat than under natural service, and 15% fewer artificially inseminated cows actually produced calves than did naturally served cows. The introduced Boran females were not inferior in calving percentage to the indigenous Ankole and Zebu.

Relationships between dam body weight and progeny performance were investigated. The introduced Boran breeding cows were able to maintain their body weight as least as well as the indigenous Ankole and Zebu cows. While cows which calved regularly and reared their calves could not maintain body weight, it was found that heavier cows conceived at a higher rate than lighter cows, cows heavier at parturition weaned heavier calves than lighter cows, and cows that reared heavier calves lost more, or gained less, body weight than cows that reared lighter calves. It was therefore indicated that investigations into the reduction of lactation stress on cows by such methods as earlier weaning of calves, mating at the most suitable time of year, and possible nutritional supplementation at a stage in the cycle, should be commenced.

The nine possible breed types resulting from the use of Angus, Boran and Red Poll bulls on Ankole, Boran and local Zebu cows were represented in the experiment. Sex, period of birth and year of birth had significant effects, at practically all ages, on body weights of calves measured at three-monthly intervals from birth to two years. Age of dam had a significant effect on calf weight at birth but not thereafter. Previous parous state of dam had only few apparently significant effects on calf weights at different ages. It appeared that beneficial effects of a good pre-weaning maternal environment might be retained, as there was no strong evidence of post-weaning compensatory growth for pre-weaning maternal effects due to age and previous parous state of dam.

Forty-eight pigs were used to compare the feeding value of barley which had been stored dry, and then hammer-milled, with that of barley stored moist, either anaerobically or treated with 1·3% propionic acid, and then rolled. The pigs were fed from 30 kg live weight for a period of 11 weeks and during this period all consumed the same allowance of dry matter. The growth rate and feed conversion ratio of the pigs given the rolled moist barley were significantly poorer than those of others given dry milled or acid treated rolled barley. There were no treatment differences in carcass attributes.

Microbiological counts made throughout the experiment showed that there was no significant fungal or bacterial development on the acid treated barley. Similar numbers of bacteria were present on the dry barley as on the moist, but the fungal count for the moist grain was always at least 500 times higher than that of the corresponding dry sample. The dominant organisms were identified.

In a further experiment the apparent digestibility of dry matter and nitrogen of diets containing dry, moist or propionic acid treated barley, processed either by milling or rolling, were determined. The highest values were obtained for dry barley. Acid treated moist barley had lower values than moist barley. The method of processing did not affect the apparent digestibility of the dry matter, but that of the N was significantly lower for the rolled barleys.

Forty-eight Suffolk × Clun lambs were used in an experiment to investigate the effects of two times of removal from the dam and two feeding frequencies upon milk intake over the first 4 days on an artificial rearing system.

Lambs removed at birth consumed significantly more milk replacer at feeding periods up to 32 hr after removal than lambs removed at 24 hr after birth. Removal at birth also significantly increased voluntary milk intake between feeding periods for up to 32 hr and from 64 to 80 hr after removal.

Feeding the lambs during a 16-hr period in a 4, 4, 8 hr sequence instead of 8, 8 hr intervals significantly improved milk intake at feeding periods.

Several groups of eight fattening (18 kg to 91 kg) Large White pigs containing both immature female and castrated male animals were established, were fed twice a day on a commercial dry ration, were observed at feeding time and their social orders (linear dominance hierarchy) worked out. Individual pigs were removed, one at a time, from different places in the social order, isolated for varying periods of time, and then replaced in their groups. It was found that the removal of a pig from any rank in the dominance order altered neither the basic social hierarchy nor the amount of aggression within the remainder of the group. The duration of time that an animal could be removed, isolated and returned without being attacked by the rest of its group varied with its social rank. Top-ranking animals could be safely returned even after 25 days' isolation, but lowranking animals were severely attacked after only 3 days' absence.