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.

The effects of exercise on food intake, growth rate and behaviour were investigated in two trials with 32 pigs. The exercise took the form of running or walking four times the length of a concrete path twice a day. Food intake and rate of gain in body weight were decreased by exercise; the thickness of back fat was not significantly affected. Exercise increased the amount of time spent resting. It is concluded that exercise does not appear to be a practical method of producing leaner carcasses.

An exceptionally high incidence of difficult birth (29% of ewes giving birth to single lambs) in a Cheviot sub-flock in 1957 was reported by Gunn and Robinson (1963). To analyse some of the factors contributing to variation in the incidence of difficult births, observations were made on three farms over a seven-year period from 1958 to 1964. The farms are Sourhope, Roxburghshire, in the Cheviot Hills, with 1000 Cheviot and 350 Blackface ewes on predominantly Festuca-Agrostis, Nardus and Molinia pastures, with no regular provision of supplementary feed; Glensaugh in the East Grampians in Kincardineshire, with 550 Blackface ewes on predominantly heather (Calluna) pasture on free draining ground, with regular provision of supplementary feed during winter and spring; Lephinmore on Loch Fyne in Argyll, with over 600 Blackface ewes on mixed pasture mostly overlying peat, with limited provision of supplementary feed during winter and spring. Further details are given in the H.F.R.O. report (1958).

1. Bulls and steers of the Yugoslav Simmental breed (38 in total) were reared and fattened to 470 kg live weight. Half received a moderate level of feeding to 8 months of age and half a high level of feeding over this period; all were fed on a high level from 8 months to slaughter, their diet involving a concentrate mixture, lucerne hay and maize silage.

2. At slaughter weight, steers were 2·5% higher at withers than bulls, but other body measurements showed no significant difference.

3. Castrates needed a 3 to 8% longer fattening period depending on the feeding treatment.

4. Castration reduced the rate of live-weight gain by 4·9% over the whole rearing and fattening period, and by 8·0% over the fattening period only.

5. Bulls had better feed conversion ratios overall. Steers consumed more starch units per kg of live-weight gain—8·1% more over the whole rearing and fattening period and 9·8% over the fattening period. Consumption of digestible crude protein was also higher in steers.

6. The detrimental effect of castration was more strongly expressed on the HH feeding treatment. An increase in the concentration of the rations did not improve food conversion ratios.

A solution of ammonium salts of a mixture of short-chain fatty acids (mainly acetic acid) was added to the sole source of drinking water of 10 lactating Jersey cows. There was considerable variation in the concentration of salts tolerated without depression in water intake. Some animals refused solution offered at a concentration of 0·5% (w/w) whereas one animal accepted solution at a concentration of 8% (w/w) and had a mean daily intake of salts equivalent to 836 g acetic acid.

2. Adjustment of the pH of the drinking solution to 6·5–7·5 increased the tolerance to the salts solution of animals which showed a low tolerance to the unadjusted solution. A mean daily intake equivalent to 480 g acetic acid was achieved without a significant depression of water intake. Replacement of 50 % of the ammonium ions by calcium increased the intake of salts by some cows but two out of eight refused the solution at a concentration of 0·5% (w/w).

3. The addition of saccharine, vanilla or aniseed to a solution of the ammonium salts gave little or no improvement in acetate intake but sodium cyclamate, ethyl acetate or molasses reduced the variability between animals in their tolerance to the solution and increased the mean intake of salts. With an addition of molasses, which gave the most marked response, there was a mean daily intake of salts equivalent to 495±26 g acetic acid.

There were 563 lambs in the study. They were single Barki lambs born during the period 1961–62 to 1965–66 in Ras El-Hekma Desert Research Station (U.A.R.). All lambs were weighed at birth and at weaning. From 1963–64 onward lambs were weighed nearly every 15 days.

Two methods of estimating growth rate were compared:

R1 = weaning weight — birth weight/age at weaning

and R2 = the regression coefficient of weight on age. The effect of method of estimation on heritabilities and genetic and phenotypic correlations was examined.

Heritability estimates of birth weight, R1 and genetic and phenotypic correlations between them were 0·18 ± 0·10, 0·24 ± 0·11, 0·50 and 0·12 respectively. From the data collected during the period 1963–64 to 1965–66 alone the heritability estimates of birth weight, R1 and R2 and the genetic and phenotypic correlations between birth weight and each of R1 and R2 were 0·15 ± 0·14, 0·39 ± 0·20 and 0·39 ± 0·20; 0·84 and 0·96; 0·28 and 0·27 respectively.

For preweaning growth rate the method of dividing the gain in weight until weaning by age at weaning was virtually as good a method as using the regression of body weight on age. The correlation between the two methods was estimated as 0·91.

Two trials were undertaken to test the effect of different levels of diethylstilboestrol (DES) on the performance of Egyptian castrated male (wether), male (uncastrated) and female lambs. Ninety crossbred lambs in groups of 10, comprising 30 wethers, 30 male and 30 female lambs were used.

Early weaning is now a well recognized and widely practised system of calf rearing which saves considerable labour compared with the former practice of giving liquid milk or milk substitutes in buckets twice daily to the age of 12 weeks.

One of the practical difficulties of bucket feeding calves twice daily is that the feeding times need to be close to the beginning and end of the stockman's working day to maintain reasonable intervals between intakes of liquid. Each feed must be followed by further time spent washing utensils. The labour demand for this can often conflict with that for milking and feeding other stock. It seemed possible that the whole of the liquid milk substitute intake of calves destined for early weaning might be provided in one feed daily with considerable saving of labour and increase in convenience.

Electrophoretic variants of certain red cell esterases of rabbits (Oryctolagus cuniculus) have been shown to be under the control of two co-dominant autosomal alleles (Grunder, Sartore and Stormont, 1965). Each allele controls two zones of esterase; those controlled by EsA migrated ahead of those controlled by EsB. The heterozygote manifests not only the zones of both homozygotes but also a ‘hybrid’ zone which appears between the A and B zones.

Profitable beef production in stickler herds depends upon each cow within the herd producing a heavy, well-grown calf every year. The weight of the weaned calf has a large effect on the producer's income. The pedigree beef breeder therefore needs to select female lines within his herd which produce calves above the herd average weight at weaning.

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.

Many observations have been made on the metabolic effects of urea (see reviews by Reid, 1953; McLaren, 1964) and on the problem of urea poisoning (Repp, Hale and Burroughs, 1955), but little information is available on the use of urea for fattening beef cattle under conventional intensive systems. There has been considerable interest shown in the use of biuret as a source of non-protein nitrogen (NPN) as it has been found to be less poisonous than urea when consumed in large quantities (Berry, Riggs and Kunkel, 1956).

From time to time in the United Kingdom and other countries skim-milk is locally in plentiful supply and very moderately priced. It is of course successfully utilised in the fattening of pigs, but it seemed to us that it might also be a useful feed for store sheep. Two feasibility studies were therefore carried out in 1964.

Weaning lambs at 8 to 10 weeks of age is widely practised in the U.S.A. The practice results in the ewes being dry for relatively long periods and affords an opportunity to reduce feed costs during that time. Jordan and Hanke (1964) maintained non-lactating ewes in drylot on 2 to 2·5 lb of legume hay per ewe daily, and Jordan and Marten (1965) doubled the number of ewe grazing days (carrying capacity) by restricting the time the ewes were permitted to graze per week to about 50% of normal. In neither study was subsequent wool or lamb production reduced.

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.

Attention has recently been focussed on the possibility of supplementing cattle diets with nutrient solutions containing ammonium salts of short chain fatty-acids (Kay, Preston, Walker, Macleod, 1965; Prescott, Shobokshy and Armstrong, 1967). This method of supplementation requires the liquid feed to be as acceptable to the cow as water or, if less acceptable, to be the only source of liquid intake. In both these circumstances there is a possibility that consumption of such liquids likely to be hypertonie will lead to water imbalance in the animal body.

The Milk Marketing Board's 23 artificial insemination (AI) centres which provide service in much of England and Wales are grouped into five geographical areas (Figure 1). Analyses of trials on commercial farms to study the effects of crossing Charolais bulls with dairy cows (Edwards et al. 1966), revealed significant differences between these areas in both gestation length and birth weight of crossbred calves. However, the Charolais bulls used in the trials were divided into five teams, each of three bulls, and each team was used only in a single area. Consequently, bull teams and areas were confounded. The purpose of the experiment reported here was to estimate the differences between areas in gestation length and birth weight independent of sire.