Southdown and Welsh Mountain female sheep, equal numbers on high and low plane nutrition, were shorn and subjected to two acute cold exposures (−20°C, 4 mph wind) in climate chambers. Before the first exposure the sheep were kept in either a cool (+8°C) or a thermoneutral (+30°C) environment for two weeks. Between exposures these environmental temperatures were reversed within groups. Blood samples were withdrawn at the beginning and end of the two week exposures and on three occasions during acute cold exposure. Plasma analyses of Ca, P, Mg, Na and K were carried out. Exposure to +8°C caused a 12% reduction in plasma Mg levels of all sheep, but had no effect on Ca, Na or K levels. There were breed × temperature interactions with respect to plasma P levels. Acute cold exposure caused reductions in plasma Mg and Ca levels and an increase in plasma P levels of all groups of sheep. Changes in plasma Na and K levels could have been caused by plasma concentration.

Electrolyte levels initially displaced by exposure to +8°C showed no evidence of a return to normality two weeks later. Only for Ca was there evidence that prior exposure to +8°C modified the response to acute cold exposure.

1. In the first experiment, the digestibility of diets containing ratios of 1:1 and 1:4 hay to concentrates was determined at five levels of feeding in castrated male sheep. With diet 1.1, increasing the daily dry matter intake from 600 to 1400 g resulted in a linear decline in organic matter digestibility from 74·4 to 68·6%. The same increase in level of feeding led to a curvilinear decline in the organic matter digestibility of diet 1.4 from 83·0 to 75·9%.

2. In a similar way the crude fibre digestibility of the diets declined as food intake increased. Also the increase in level of feeding caused a decrease in the mean retention time of stained hay in the alimentary tract.

3. In a second experiment the digestibility of long dried grass offered ad libitum to eight dry and eight lactating cows was measured and compared with the digestibility of similar dried grass offered at maintenance level and ad libitum to eight castrated male sheep.

4. On a metabolic live-weight basis (kg W0·73), the lactating cows ate 34% more organic matter than the dry cows and the mean voluntary intake of sheep was only 54% of the intake of dry cows.

5. The organic matter digestibility for the dry cows was 1·9 units higher than that of the lactating cows and at ad libitum intake the organic matter digestibility for the sheep was 5·6 and 3·7 units lower than that of the dry and lactating cows respectively. The results are discussed in relation to the validity of extrapolating results obtained with sheep to cattle, and with non·lactating to lactating animals.

The Society was founded 25 years ago, in January 1944, and this is perhaps a fitting occasion to look back on its origins and to give a short account of its growth and achievements.

Genetic parameters of veal calves were estimated from data on 510 Danish Red male calves by 39 sires.

Heritability estimates for the growth and carcass traits were low, those for body dimensions and dressing percentage high.

Correlations between the growth and carcass traits indicated no genetic incompatibility in selection.

The problem of achieving simultaneous improvement in the dairy, carcass and growth qualities is discussed. It is suggested that the adoption of performance testing for growth and carcass quality prior to the entry of bulls into AI service, followed by progeny testing for milk and fat yields, would provide the best method of genetic improvement.

A survey of albumin polymorphism in the major breeds of cattle in the British Isles is described. Four and probably five alleles have been found. AlbA is the common type in all breeds. AlbB occurs with less than 1 % frequency in all breeds except Sussex and Charolais, where it has a frequency of 12% and 16% respectively. The possible implications of this finding are discussed. The other alleles AlbC(Ed) and AlbD are extremely rare, and are confined to a few animals each within one breed. AlbG has been tentatively proposed as the name for a new albumin type.

Repeatability estimates for various maternal characteristics were calculated for 301 inbred, 150 outbred and 135 linecross Large White sows each with two litters. The estimated repeatabilities did not differ significantly between the three kinds of sow and the arithmetic average of the values obtained were as follows: number of pigs born alive 0·24; number of pigs born dead 0·05; total birth weight of litter 0·25; average individual birth weight 0·41; number of pigs alive at 50 days 0·07; total litter weight at 50 days 0·14; average individual weight at 50 days 0·15.

The linecross sows produced and weaned more pigs than the outbred sows, which in turn performed better than the inbred sows. Changes in performance from the first to the second litter were similar for all three groups of sows.

Body composition of a pair of related double-muscled and normal Aberdeen Angus females was analysed. The following ratios of weights of body components of the double-muscled individual to the normal were found: empty body, 1·0; carcass, 1·1; total muscle, 1·4; carcass fat, 0·7; offal fat, 0·9; viscera, 0·9; hide, 0·8; ash (in carcass), 1·0. The data supported an hypothesis of generalized muscular hypertrophy. The empty body weight of the normal female was 474 kg.

1. An experiment to test the effects on growth rate of lambs to 15 kg live weight of 5, 7 or 9 kg of milk replacer powder given according to four systems of daily restriction is described and the results are discussed.

2. Although the average age at weaning varied from 18 to 50 days according to treatment, the quantity of milk replacer did not affect the lambs' overall growth rate. Lambs deprived of milk consumed extra concentrates at a rate of 1·75 ± 0·219 kg per kg of milk powder.

3. Although severe restriction of the daily allowance markedly reduced the growth of lambs during the milk-feeding period, they subsequently grew at a faster rate and there was no resultant major depression of overall growth rate. The lambs first consumed a measurable quantity of solid food when they were on average 21 days old and this varied little according to treatment.

4. It is concluded that under the conditions of this experiment it was not economic to give more than 5 kg of milk powder and that it was not advantageous to adopt distribution systems that delayed weaning much beyond 20 days.

5. The applicability of these findings to practice is discussed in relation to the possibility of treatment effects from the rearing period being carried over to the period beyond 15 kg live weight, and also to the possible effects of single penning versus grouping on lamb behaviour.

Samples of sheep's milk were used to study the occurrence of β-lactoglobulin variants of fast or slow electrophoretic mobility. The distribution of variant types between a sample of daughters and their dams was in general accord with simple Mendelian expectations for two autosomal co-dominant alleles.

A sib selection programme for length of carcass was carried out for fivegenerations within a closed herd of Large White pigs. A generation intervalof one year was obtained.

Litter production was good throughout the project and the numbers of pigs born and reared in the final generation were 11·2 and 10·3 respectively.

Overall response to selection was predicted with reasonable success. The increase in length was associated with an increase in number of vertebrae.

Heritability for length of carcass computed from the pooled components of variance was 0·53 ± 0·12. Realized heritability was 0·5 ± 0·1. No control strain was maintained.

Correlated traits moved in the expected directions and responses were beneficial for traits such as backfat measurements and chest depth, but unfavourable for belly thickness and ham conformation. Carcass acceptability was not good initially and this deteriorated during the project. The difficulties involved in maintaining selection pressure and herd size are discussed. Abnormalities and lameness were recorded and did not increase systematically over the experiment.

It is suggested that the specific relationships between ‘conformation’, carcass value and viability require further investigation with particular reference to length of leg and length of carcass.

The relationships among five traits in dairy cattle (milk yield, fat yield, protein, fat % and protein %) were examined on the original and on a logarithmic scale. The data comprised the records on 5333 Red Danish cows tested at the Danish Progeny Testing Stations during the years 1960–66. None of the heritabilities or the correlations among the variates were altered appreciably by transformation. For the five traits heritability estimates were 0·56, 0·80, 0·65, 0·64 and 0·56, respectively. Phenotypic and genetic correlations among milk yield, fat yield and protein yield were all very high, about 0·95. The correlations between fat % and protein % were about 0·6. The coefficient of variation of a variate proved to be a good approximation of the standard deviation of the transformed variate even for milk, fat and protein yield with coefficients of variation of 17–18%. It was concluded that little is likely to be gained by using index selection for fat yield and protein yield. However, about 90% of the response obtainable by direct selection for fat or protein yield could be obtained merely by selection for milk yield. A large correlated response for protein yield could be obtained by selecting for fat yield.

1. Four growth trials were carried out with 297 group-fed steers given diets based on barley, minerals and vitamins, unsupplemented or supplementedwith either soya bean meal or various sources of non-protein nitrogen.

2. Steers given unsupplemented barley (11% crude protein in dry matter) had inferior growth rates up to 300 kg live weight but thereafter were equal to those given barley supplemented with urea in the drinking water or soya bean meal.

3. There were no significant differences in the growth rates of steers given barley supplemented with soya bean meal and those given barley supplemented with ammonium and mineral salts of formic acid or a mixture of acids (predominantly acetic).

4. In two out of three trials, tenth-rib joints from steers given barley supplemented with ammonium salts of mixed acids contained less fat and more protein and water than those from steers given barley supplemented with soya bean meal or proprietary protein supplements.

5. A number of possible explanations for the apparent carcass differences is discussed.

1. A comparison lasting 3 years has been made of 5 types of crossbred ewes produced by mating Border Leicester, Clun Forest, Dorset Horn, Finnish Landrace and Tasmanian Merino rams to Scottish Blackface ewes. Data from a total of 576 ewe years became available.

2. In body weight at mating time when they were 7, 19 or 31 months old, the Border Leicester and Dorset Horn crossbred ewes were heaviest, followed by Cluns. Finnish and Merino crossbreds were about 15–20% lighter than the Border Leicester crossbreds.

3. In fleece weight, Finnish crossbreds were lower by about 1·0—1·5 lb relative to Border Leicester crossbreds.

4. In fertility, Finnish crossbreds were highest with 1·5, 2·0 and 2·3 lambs born per ewe lambing at ages 1, 2 and 3 years respectively. The corresponding averages for the combined Border Leicester, Clun and Dorset Horn crossbreds were 1·1, 1·6 and 1·6 and for Merino crossbreds 1·0, 1·1 and 1·2. Numbers weaned were similarly ranked.

5. Lambs out of crossbred ewes showed a sequence of group differences in weight at birth and at weaning corresponding to those shown by their mothers at mating time. The heaviest lambs were produced by Dorset Horn and Border Leicester crossbreds, and the lightest by Merino crossbreds. As a percentage of ewe weight at mating, lamb weight at weaning was highest for the Finnish group.

6. In terms of litter weight at weaning, fitted values for the Merino group were the lowest while those for the Finnish group were the highest. Theother three groups gave similar and intermediate values.

1. Four treatments were employed in the rearing of colostrum-deprived piglets from birth to 14 days of age. The performance of the artificially reared piglets was compared with that of conventionally raised sow-suckled piglets.

2. Statistically significant differences in growth rate were found in favour of piglets receiving 22% cows' milk solids from birth when compared with the sow-suckled group and the other artificial treatments.

3. Small non-significant differences in feed conversion efficiency were found between the artificial treatments with one exception. Pigs receiving 22% cows' milk solids from birth possessed superior conversion figures when compared with pigs receiving 6% cows' milk solids after birth.

4. Each of the artificial treatments led to fewer deaths than the sow-suckled group.

5. Pigs on the artificial treatments did not undergo such rapid changes of serum protein profile as did the sow-suckled piglets. Serum protein values for the pigs on the artificial treatments rose from approximately 33% of the levels in the sow-suckled group at two days of age to approximately 60% at 14 days of age.

In parts of the United Kingdom, considerable numbers of Ayrshire bull calves are slaughtered at birth or shortly after. These animals, if fattened intensively on a cereal diet, could provide a valuable addition to the beef produced from the dairy herd if their rate of live-weight gain, carcass composition and feed conversion efficiency provided an economic return. At the prevailing purchase price of calves and cost of feed the profit margin would appear to compare favourably with that from other dairy steers. The data from an economic survey of barley beef units in the North of Scotland by Clark (1966) show, on the basis of surplus per head (i.e. gross margin less other costs) that the greatest margin was achieved by a unit whose livestock was entirely comprised of Ayrshire steers.

An account is given of the conception rates (in terms of calves born) following artificial insemination of contemporary purebred and crossbred cattle derived from purebred Friesian, Ayrshire and Jersey stock in an experimental herd. First inseminations were given to 222 purebred and 495 crossbred females approaching first pregnancy; and to 165 purebred and 347 crossbred females approaching second pregnancy. Fitted values for conception rates showed no noteworthy differences for year, season, age of female, or breed of bull. Crossbred females, however, were about 10% more likely to conceive than purebreds. Purebred females mated to bulls of their own breed showed lower conception rates than those mated to bulls of another breed.

In reporting on the Charolais importation of 1962, Edwards et al. (1966) noted different average growth rates of calves born at different times of the year: spring born calves for instance were slowest at 1·67 lb/day and autumn born calves fastest at 1–80 lb/day. The Beef Recording Association (1967) has also reported that growth rates for castrated males in commercial intensive cereal feeding beef lots consistently reflected seasonal effects on growth. In both cases the data were derived under conditions which did not permit detailed investigation of seasonal changes in the growth curve.