Two experiments were carried out to compare the performance and carcass quality of pigs given diets based on barley, wheat or maize meal, and another two experiments comparing these cereals, flaked maize and sorghum. In general, differences in the utilization of feed for live-weight gain could be related to differences in the digestible energy content of the cereals used in the diet, although in some experiments pigs behaved atypically on individual diets. Flaked maize was consistently inferior to the other cereals in the efficiency of conversion of its digestible energy, possibly because of its poorer amino acid balance and its low levels of lysine and tryptophan in relation to energy. Differences between experiments in the performance of pigs fed on the various diets are also discussed. Differences between treatments in killing-out percentage and predicted lean percentage were small, and carcasses of pigs from all treatments were acceptable for bacon curing.

Data from a boar progeny testing scheme based on ad libitum feeding were analysed to test the hypothesis that the resultant correlations of food conversion ratio with related factors would differ from those found under conditions of restricted feeding.

The results support the hypothesis, showing that the primarily genetic correlations derived from boar effects for growth and conversion ratio, are lower than those reported elsewhere for restricted feeding. It was also shown that these primarily genetic correlations could vary between breeds, the leanness associated with rapid growth in Wessex not being found in Large White, and that the correlations due to residual effects containing a greater environmental component varied widely from test to test.

It is concluded that the parameters used in the design of a genetic improvement scheme should be derived specifically for each breed and feeding system. However, if the marked variability in phenotypic correlations noted here is generally applicable, this could present a difficult problem in the design of pig improvement programmes with multiple objectives.

Two experiments were carried out to study the energy requirements of young fattening lambs for maintenance and production. Forty weaned lambs were used in each experiment, 20 being allocated to a high level of feeding (900 g air-dry feed per day) and 20 to a low level (540 g). The animals used in Experiment 1 were approximately 12 months of age and their mean live weight was 35·3±4·03 kg. Those in Experiment 2 were approximately seven months of age and their mean live weight was 36·7 ± 4·57 kg. Experiment 1 continued for 100 days and Experiment 2 for 47 days. Three digestibility trials, involving three animals from each feeding level, were carried out during the course of each experiment to obtain precise estimates of digestible organic matter intake (DOMI). The estimated mean DOMI required for maintenance for a 45-kg lamb was 400 g (0·88 lb) or 1500 kcal metabolizable energy per day. The estimated maintenance requirement was not affected by the age of the animal. The DOMI required for production ranged from 1·55 kg per kg live-weight gain for the younger animals to 1·71 kg for the older animals. Both these requirements were lower than those obtained by other workers and those suggested by the Agricultural Research Council (1965).

In the first of two experiments, steers which received a single implant of 60 mg hexoestrol grew 24% faster than non-implanted controls and 7% faster than steers given 30 mg. The growth rate of the steers given a single implant of 60 mg did not differ significantly from that of animals implanted twice with 30 mg or 5 times with 15 mg. In the second experiment, steers given 60 mg grew 23% faster than controls and their feed conversion efficiency was 13% better; the hexoestrol treatment resulted in a saving of 131 kg feed per animal. The tenth-rib joints of steers given 60 mg had a higher crude-protein content and lower fat content than those from non-implanted animals.

Three trials have been made with growing pigs to measure the digestibility of four samples of wheat offal. Two samples were measured at the levels of 0, 20, 40 and 60% of the diet and two samples were measured at the levels of 0 and 60% of the diet. The offal replaced equal quantities of glucose in the diets and no attempt was made to equalize nutrient levels between diets.

Apparent digestibility coefficients of the diets declined with increasing dietary wheat offal content, but the digestibility of wheat offal did not change with level of inclusion. No differences in digestibility occurred between offals from hard and soft wheats, apart from a low N digestibility in one sample of soft wheat offal. The average digestible energy and TDN contents were 2810 kcal/kg and 63·1 for samples of offal containing 12·5% moisture.

The frequencies of calving difficulties were computed for 458 calvings of first and second parity Friesian, Ayrshire and Jersey dams with pure and crossbred progeny in all possible combinations. It was found that heavier breeds of dams have higher frequency of difficult calvings. For each breed of dam there is also a direct relationship between the mean birth weight of the calves and the frequency of calving difficulties associated with the breed or cross of calf.

An index of calving difficulties calculated in the form of a discriminant function which combined both the birth weight of the calf and the calving weight and parity of the dam was:Z = log BW−0· log DW−0·10 P,

where Z is the index of calving difficulties, BW and DW are respectively the birth and dam weight and P the parity variable withthe values of one for second parity and zero for the first.

A dramatic fall in the colostral whey proteins of nine sows occurred within 24 hr following the birth of the first piglet. The mean levels fell from 19·6 g/100 ml to 4·1 g/100 ml, 50% of this fall occurring within 4 to 6 hr. It is suggested that as early-born piglets will be able to obtain colostrum of a much higher protein concentration this may give them some physiological and immunological advantages over later-born littermates.

Data were obtained on 3028 lambs born during five successive years from 1961 to 1966 at Ras El-Hekma Desert Research Station in the Western Coastal Egyptian Desert. Breed groups involved in the study were Hungarian Merino, Syrian Awassi, native Barki sheep, and nine of their crosses. The characters studied were birth weight, weaning and yearling weights, pre- and post-weaning average daily gain and yearling greasy fleece weight. The effects of breed group, year of birth, sex, age of dam and type of birth on these characters were investigated.

The results obtained showed that Barki lambs excelled Merino lambs in all the traits related to body growth. Merino lambs, on the other hand, excelled Barkis in fleece weight. Barki lambs also excelled Awassi lambs in all traits except birth and weaning weights. In all characters except pre-weaning gain, the first cross of Merino and Barki (½M½B) was markedly superior to all the other crosses and pure breeds. The two third-crosses, ⅜ M ⅝ B and ⅝ M ⅜ B, were similar to each other in their productive traits and were slightly inferior to the first cross. The two back-crosses, ¼M¾B and ¾M¼B, were markedly different from each other, the former being better than the latter. The three-eighths Merino group is suggested for developing a new strain of sheep for the semi-arid regions. The effects of the environmental factors on the six characters studied were all highly significant except for the effect of sex on fleece weight and the effects of age of dam and type of birth on growth from weaning to yearling ages. The most important factor affecting the different traits was year of birth. Type of birth and age of dam were important sources of variation only for the characters studied till weaning age, but became of little importance thereafter. The effect of sex was pronounced only on yearling weight.

Records on 695 lambs were collected over a period of 5 years from 1961/62 to 1965/66, at Ras El-Hekma Desert Research Station, 230 km west of Alexandria. The characters studied were birth, weaning and yearling body weights, pre- and post-weaning daily gains and greasy fleece weight.

Birth, 120-day and 365-day body weights were 3·4, 18·2 and 33·4 kg respectively. Greasy fleece weight at 16 months of age was 3·29 kg. Heritability estimates of birth, weaning, yearling weights, pre- and post-weaning daily gains and greasy fleece weight were 0·22, 0·45, 0·41,0·45 and 0·29 respectively. Genetic and phenotypic correlations between birth, weaning and yearling weights were all positive and significant. Genetic correlations between fleece weight and body characteristics were negative and low.

Colostral whey protein levels do not change during the first 4 hr from the start of parturition when suckling is prevented. Both early and late-born piglets returned to the sow at the end of this period are able to suck colostrum of a high protein concentration. Removal of piglets from the sow and the presence of an attendant did not affect the farrowing process.

The lactation curve in cattle has been explained by the expressionyn = Anbe-cnwhere yn is the average daily yield in the nth week, and A, b, and c are constants. In general, in a sample of 859 Friesian lactations recorded during 1964–65 daily yield was depressed during the winter months (18·8% in January) and stimulated during the spring (14·7% in May) to an extent which was independent of the stage of lactation. Winter calvers on the other hand tended to produce more in total lactation than spring calvers (14·5% for animals calving in November as opposed to those calving in April).

Using a suitable technique it is possible to predict month by month output from a cow, or herd, accurately enough to furnish a basis for forward planning.

A small scale ewe-recording scheme, involving a minimum of weighing, is described. Results for two years and two breeds have been analysed to produce correction factors in each year for birth type, sex and age of dam in respect of birth weights and weights at 84 days of age derived with and without reference to birth weight. The results suggest that breed differences in correction factors may exist and that differences between years in correction factors may be of minor importance. In standardizing weaning weights to a constant age the influence of birth weight appeared to be relatively unimportant.

Year, type of gestation (single or twin foetuses) and age of foetus all had highly significant independent effects on both foetal weight and length (P>0·01). Twin foetuses were both longer and heavier than single foetuses at 21 to 30 days post coitum. Continuous illumination, continuous darkness and intermittent light appeared to reduce foetal length and weight (P>0·05). Control foetuses were longer and heavier than those on other treatments. Neither feeding level (75 to 150% N.R.C. maintenance requirements) nor body weight of the dam had significant effects on foetal size within the age range studied.

The growth and carcass characteristics of autumn-born Hereford × Ayrshire castrated male calves reared on two planes of nutrition have been studied. Restricted feeding for 12 weeks after weaning from liquid feed to the time the calves were turned out to grass created a difference of 52·0 lb per head in live-weight gain and 15·2 lb of this difference persisted at slaughter. There were small differences in carcass conformation and composition.

A portable EEL reflectometer was modified to measure the variations in the brightness of pig meat. The instrument was calibrated spectrophotometrically with reference to the luminous reflectance of standardized materials and selected meat samples. A very satisfactory level of agreement between the instrument and the visual assessment of muscle paleness was found in an investigation involving 251 pigs.

Eight research and teaching centres have co-operated in an experiment involving 132 sows. Six treatments were used, combining three levels of feeding in pregnancy with two in lactation. Pregnancy treatments were High 3−2 kg meal/day, Medium 2·4 kg/day and Low 1·6 kg/day; in lactation either a high level, 4·1 kg plus 0·2 kg/pig (h) or a medium level, 2·3 kg plus 0·2 kg/pig (m) were given. The sows were maintained on the same nutritional regime for three parities although inevitably some sows were lost before the completion of the trial. Sow live-weight gains in pregnancy were directly related to feed intake; in lactation, losses in sow live weight were dependent on gains made in the previous pregnancy and on the level fed while suckling. After the first parity, in which animals fed the low level in pregnancy tended to produce larger litters (though the difference was not significant), there were no differences in numbers born attributable to treatments.

Increases in the feed intake of sows in pregnancy resulted in consistent and significant increases in the weight of the pigs at birth. This increase in birth weight also resulted in an increase in weight at weaning in the second and third parities. Level of feeding in lactation, which had a highly significant effect on sow live weight, had much less influence on weaning weights of pigs. There were no consistent pregnancy × lactation interactions, the effects of treatments in the two phases being additive.

An assessment is made of the relative efficiency of the six treatments and the value of the experiment is discussed in relation to other studies concerned with sow nutrition.

Voluntary hay intake and milk yield were measured in 11 singlesuckling and 4 twin-suckling ewes for the first seven weeks of lactation. There was no significant difference between the intakes of the two classes of ewe and milk yield differed only in the seventh week. Variations in milk yield and live-weight change were significantly associated with variations in voluntary intake. Lamb weight gain was correlated with milk yield and voluntary intake of the dam.