(1) Two trials on the effect of copper glycine injections on the live-weight gains of suckling beef calves under commercial conditions are described.

(2) One injection supplying 120 mg. of copper increased live-weight gains by approximately 10% during the suckling and grazing period. A second injection given two months after the first gave a further positive but not statistically significant response.

The design and manufacture of plastic cannulae are described and the chief hazards associated with cannulated re-entrant fistulae in sheep are discussed.

1. Thirty-two individually-fed pigs were used to determine the effects of soaking their daily meal ration in either water or in liquid skim milk and water for approximately 24 hr. before feeding. The experimental period continued from about 10 weeks of age to bacon weight.

2. Neither soaking procedure had any significant effect on the rate of growth, efficiency of food utilisation, dressing percentage, carcass length, backfat thickness or commercial grading results of the pigs.

3. The growth rate and efficiency of food utilisation of the pigs given meal plus skim milk were significantly better than for those given the all meal diet. The dressing percentage of the former was also significantly higher than the latter, but there were no significant differences between the two groups in carcass length or backfat thickness.

4. Possible reasons for the difference in performance of the all meal and meal plus skim milk-fed pigs are discussed.

1. Analyses of records of eight-week body weight in broiler chickens have been carried out to estimate the effect of management level (measured by mean body weight of all varieties on each farm) on the components of variance due to differences between and within varieties, and to find out if there is any evidence of genotype-environment interaction.

2. It was found that as management improved, the between-variety genetic variance remained constant or possibly increased whilst the withinvariety (genetic and environmental) variance decreased markedly. The cause of these regressions is not known.

3. In four cases out of six there were significant genotype-environment interactions. In two cases, the genetic correlation between the performance of varieties on different locations was significantly different from 1·0.

4. It is suggested that on the basis of these findings it would be necessary to select between varieties on records taken from chickens maintained under conditions similar to those in which they will eventually be used. However, fewer chickens would be required to measure, with a predetermined level of accuracy, mean differences on well managed farms than on poorly managed ones.

An analysis has been made of milk production data from indigenous East African zebu cattle at the Baraton, Maseno and Sangalo Livestock Improvement Centres in Kenya, covering a period of twenty-five to thirty years.

The relationships between milk production and length of lactation, dry period, calving interval, month of calving and age were examined. Lactation length accounted for from 53% to 66% of the total variance in milk yield. Variations in length of dry period caused significant differences in milk yield between, but not within cows. Increasing length of previous calving interval improved current lactation milk yield but month of calving had no significant effect. Yield increased from first to second lactation by 8% after which it remained relatively constant up to the fifth lactation. Age at first calving was positively correlated with first lactation milk yield.

Intra-herd repeatabilities were 0·55 for milk yield, 0·38 for lactation length, 0·17 for calving interval and 0·12 for dry period. The highest estimates of heritability were those obtained for lactation yield and length (0·5); the lowest, for calving interval, was close to zero. All heritability estimates had high standard errors. The probable genetic improvement in milk production achieved by the selection practised in the herds was estimated as ranging from zero to 0·15% of the average yield per year.

A genetic study of the grading-up of the East African zebu to the Indian Sahiwal has been undertaken on records, covering about 25 years, from three Livestock Improvement Centres in Kenya. It appears from this study that the indigenous East African zebu cow has only about half the genetic potential of the Indian Sahiwal for milk production, and the scheme of gradingup has resulted in substantial and worthwhile increases in milk production.

A small flock of 16 Blackface ewes occupying 40 acres of hill ground grazed as a fairly tight community. From observations over a complete year, 1960, it has been shown that sheltering behaviour was largely dependent on wind speed exceeding 24 m.p.h. Sheltering increased markedly at temperatures below freezing. Temperature above freezing, except for rapid falls in temperature exceeding 4° F., exerted little effect on sheltering. No relationship could be found between sheltering behaviour of the sheep and other factors which included rain, relative humidity, wind direction or season of the year.

It would appear therefore that the sensitivity of sheep to exposure is influenced more by wind speed than any other climatic factor.

1. Four roughages were given ad lib. to each of eight steers. The amount consumed and the apparent digestibility of the energy of each roughage were determined together with the weight gains of the steers.

2. The mean voluntary intake of dry matter was related to the mean apparent digestibility of the energy of the roughages in the same quantitative way for the steers as had been noted with sheep. Mean weight gains were proportional to the mean number of calories of energy apparently digested.

3. Significant differences between individuals occurred in their voluntary food intakes, and those animals which consumed most digested it least efficiently. The variation in intake from individual to individual expressed as a standard deviation was ±7·5% of the mean.

4. The quantitative similarity of sheep and cattle as far as the relationship between their voluntary consumption of food of different apparent digestibility is concerned, is contrasted with their dissimilarity with respect to fasting metabolism. It is suggested that sheep are likely to prove more efficient convertors of the energy of roughages to body gain than are cattle.

Further work is clearly necessary to explore the extent of these differences.

In 1,347 parentage cases in cattle it was determined whether conception resulted from the first or second service. Among cows served twice within short intervals (1–11 days) about 20% remained pregnant from the previous service. At an interval of one day this proportion amounted to 37%.

About three-quarters of the cows had service intervals of 18–24 days. In most of these the calving took place between the expected dates according to the two services. In 6% of the cases with intervals of 18–24 days pregnancy resulted from the first service. It was estimated that about 1% of all cows mated twice within these intervals had become pregnant from the first service.

Rules are suggested for when blood grouping should be required for registration of pedigrees in the herd book.

The effects of sex, twinning and age of ewe on birth weight, weaning weight and fertility have been studied in 5 years' records of a small grassland flock of Wiltshire × Blackface crossbred ewes with the object of providing provisional correction factors for these variables in recorded flocks under similar management. All these variables produced large effects in the flock studied. On birth weight these were; sex, 0·6 lb.; twinning, 2·1 lb.; hogg's lamb, 2·3 lb. The corresponding adjustments for weaning weight were 7 lb., 14 lb., and 11 lb. Ewes first bred as hoggs subsequently performed well.

Since the year 1900 the number of Border Leicesters has been fairly stable, between 3,000 and 5,000 females being registered each year. The number of flocks, however, has shown a fairly steady increase from 200 to over 600. There has been a decline in the number of ewes registered per flock from 16 to about 6 to 8. The important flocks would seem to number 15 to 20; only a few flocks persist for any appreciable length of time. Generation intervals are short, being only about 2 years on the sire side and 3½ years on the female side.

As with other breeds, relatively few rams have an importance out of proportion to their numbers—14 rams and 2 ewes with direct coefficients of relationship greater than 5% were found. Inbreeding per generation was only 0·32%, and there was no evidence of strain effects.

Complete chemical analyses of all body components of 20 Large White pigs were carried out. At the average live-weight of 90·3 kg. (empty body weight 86·5 kg.) the total protein content was found to be 12·7 kg. and that of the chemical fat 25·4 kg. The edible parts of the carcass (i.e. lean and separable fat) contained only 58·5% (range 55·2–61·3) of the total protein but as much as 85% of the total chemical fat. Simple and multiple correlations were computed between various carcass characters and protein, chemical fat and energy content. The results indicate that it may be possible to obtain fairly accurate estimates of the chemical composition and energy content of the edible parts of the carcass, of the whole carcass, and of the empty body by methods based on various systems of assessing the carcass quality.