Low-glucosinolate rapeseed meal (<20 μmol/g) is likely to replace the high-glucosinolate meal currently produced in the UK, and in this experiment the use of low-glucosinolate rapeseed meal (RSM) as the sole protein supplement in a compound feed for milk production in cows was assessed. There were three compound concentrate feeds of similar energy and protein content, 0% RSM (group A), 15% RSM (B) and 30% RSM (C). The additional protein in diets A and B was provided as soyabean meal (SBM).

Eighteen Friesian cows were divided into three groups, balanced with regard to previous yield and number of lactations, and three weeks after calving were given one of the compound feeds in a 3x3 changeover experiment; each of the three feeding periods was four weeks. Barley meal was given as a parlour feed, 1 kg air dry at each milking, and the compound concentrate and grass silage were given at Broadbent-Calan gates in quantities related to expected milk yield.

To compare the genetic group differences in live-weight gains, efficiency of food conversion (in terms of dry matter, total digestible nutrients, digestible crude protein, digestible energy and metabolizable energy) and physiological responses related to heat balance, a total of 24 male lambs (91 to 180 days old), four each of Malpura, Sonadi, and their crosses with Dorset and Suffolk breeds, were given a ration having a roughage to concentrate ratio of 250:750g/kg and metabolizable energy content of 100MJ/kg dry matter. Live-weight gain per day was higher and the food conversion ratio (the intakes of total digestible nutrients, digestible energy and metabolizable energy per kg gain) was lower in the crossbreds than in the native sheep. The crossbreds had higher respiratory rates (153 per min) than the natives (140 per min) but there was no significant difference in rectal temperature between purebreds and crossbreds. The crossbred lambs in the present experiment grew faster, consumed more food and utilized the food more efficiently than did the native lambs, despite the fact that they dissipated more energy as body heat. It was, therefore, concluded that the crossbreds performed better than the native breeds between 3 and 6 months of age, even though they were not permanently acclimatized to hot environmental conditions.

Cholecystokinin (CCK) can exert multiple actions on intestinal motility but its effect on the small-intestinal ‘minute rhythm’ (MR) is virtually unknown. Therefore, the electrical activity from the abomasal antrum, duodenal bulb, duodenum, jejunum and ileum was continuously recorded in six sheep before, during and after slow intravenous administration, of three doses each, of cholecystokinin-octapeptide (CCK-OP) and cerulein. In four of these sheep, two additional electrodes and the strain gauge force transducer were also inserted in the duodenum. Chronic experiments were performed in the fasted and non-fasted animals and saline or CCK peptides were injected during phases 1, 2a or 2b of the duodenal migrating myoelectric complex (MMC). The administration of both CCK peptides in various doses evoked an inhibitory effect mostly in the duodenal bulb, except for the lowest dose of cerulein. The effects of 20 times greater doses of CCK-OP than that of cerulein were more pronounced. The introduction of both CCK peptides during phase 1 of the MMC produced no marked or significant response. In non-fasted animals, the effects of both hormonal peptides, given during phase 2b of the MMC, were often stronger than those given during phase 2a, while in fasted animals the effects of CCK peptides, administered in the course of phases 2a and 2b of the MMC, were similar. Both higher doses of CCK peptides increased the number of spike bursts within the given MR pattern in the duodenum and decreased the incidence of MR mostly in the duodenal bulb. The inhibitory effects of both CCK peptides on the bulbar MR exhibited a dose-response character, though the lowest dose often evoked the slight stimulatory response. It is concluded that CCK principally exerts an inhibitory effect upon the MR in the duodenal bulb and modifies the MR in the duodenum by increasing the spike burst number in a given MR pattern. Both these actions of CCK peptides seem to be physiological. There is a positive relationship between the intensity of the refractory period and the demonstrated effect of CCK in the duodenum.

The objectives of the trial were to Investigate the effects of long-term administration of bovine somatotropin (BST) from week 2 and 10 post-partumn on the yields of milk, milk components, body weight, body condition, health and reproductive status during the first lactation of dairy heifers.

19 Friesian dairy cows in their first lactation were allocated at calving to one of 3 treatments: Daily subcutaneous Injection of recomblnantly derived bovine somatotropin (25 mg/d) from either week 2 (BST2;n=6) or week 10 (BST10;n=6) of lactation, or injection of buffer solution from week 2 of lactation (C;n=7). Treatments continued until week 42 of lactation, or until 60 days prior to predicted calving date, if this occurred before week 42 of lactation. Initially cows were housed in cubicles and fed ad libitum individually through calan doors, on a diet of concentrate and grass silage (Table 1) on a 60:40 dry matter ratio. In approximately mid-lactation cows were turned out to grass but continued to receive concentrates according to milk yield and body condition. Milk yield was recorded daily and milk composition twice weekly as were live weight and body condition. Health and reproductive status were monitored over the lactation.

In pigs growing from 20 to 70 kg live weight, the addition of 40 g sodium bentonite to each kg diet was without significant effect on growth performance under ad libitum and restricted feeding regimes. Sodium bentonite appeared to be indigestible and inert, as dry-matter digestibilities were reduced from 0·87 to 0·85 and 0·83 by the addition of 20 and 40 g sodium bentonite per kg diet respectively.

Single-step genomic BLUP (ssGBLUP) has been widely used in genomic evaluation due to relatively higher prediction accuracy and simplicity of use. The prediction accuracy from ssGBLUP depends on the amount of information available concerning both genotype and phenotype. This study investigated how information on genotype and phenotype that had been acquired from previous generations influences the prediction accuracy of ssGBLUP, and thus we sought an optimal balance about genotypic and phenotypic information to achieve a cost-effective and computationally efficient genomic evaluation. We generated two genetically correlated traits (h2 = 0.35 for trait A, h2 = 0.10 for trait B and genetic correlation 0.20) as well as two distinct populations mimicking purebred swine. Phenotypic and genotypic information in different numbers of previous generations and different genotyping rates for each litter were set to generate different datasets. Prediction accuracy was evaluated by correlating genomic estimated breeding values with true breeding values for genotyped animals in the last generation. The results revealed a negligible impact of previous generations that lacked genotyped animals on the prediction accuracy. Phenotypic and genotypic data, including the most recent three to four generations with a genotyping rate of 40% or 50% for each litter, could lead to asymptotic maximum prediction accuracy for genotyped animals in the last generation. Single-step genomic best linear unbiased prediction yielded an optimal balance about genotypic and phenotypic information to ensure a cost-effective and computationally efficient genomic evaluation of populations of polytocous animals such as purebred pigs.

Pigs with inbreeding coefficients, ranging from 0·125 to 0·375 were analysed for effect of inbreeding on daily carcass gain, body length and meat proportion in the carcass. The foundation animals were back crosses of a Landrace boar of his daughters which were Yorkshire Landrace hybrids. The statistical model included effect of sex and slaughter weight in addition to the effect of inbreeding. A statistically significant effect of inbreeding on daily carcass gain was found with a linear decline of 1·6 g for 0·1 increase in inbreeding coefficient. There was no effect of inbreeding on body length and meat proportion. Carcass weight had a highly significant effect on body length and daily carcass gain. Effect of sex was statistically significant for meat proportion only.

Calving date (CD) records of 68 896 polled Hereford dams of 120 682 calves were coded within herd-year-season with date 1 being the date the first calf was born. Factors affecting CD and its relationship with production traits were investigated. Early calving was found to be associated with high performance, conceivably because dams calving early were able to utilize the season-dependent range pastures to their advantage thus providing adequate milk supply to their calves. Weight and age of dam, weight of calf, initial CD, index of milk production potential, and previous CD were found to have significant influence on current CD. Extremely small cows at previous weaning had a tendency to calve late. Cows calving in the spring produced calves with higher overall weight per day of age than did cows calving in other seasons. Initial CD was found to affect CD in subsequent parities. Repeatability of CD was estimated at 0·23. Heritability was estimated at 0·16 (s.e. 0·05) and indicated that additive genetic variance constitutes a moderate proportion of the variation in CD. Genetic correlation of CD with birth weight (−0·30, s.e. 0·10), post-weaning rate of gain (·0·64, s.e. 0·19) and yearling weight (−0·60, s.e. 0·11) indicated that ‘plus’ additive genes for CD influenced these traits favourably. However, the corresponding correlations with pre-weaning rate of gain (−0·03, s.e. 0·08) and weaning weight (−0·05, s.e. 0·03) were not significant.

A total of 178 castrated male cattle (steers), the progeny of Charolais, Hereford and Limousin bulls mated to Holstein-Friesian and Ayrshire cows, were raised from 8 months of age to 545 kg (slaughter weight) on fast- or slow-gaining regimes. The steers on the fast gaining regime were fed a grain mixture with little hay, while those on the slow-gaining regime grazed all summer and were wintered on hay supplemented with a little grain.

The steers on the fast-gaining regime were more efficient in feed conversion ratio, had 0·42 kg per day higher live-weight gain, reached slaughter weight 306 days earlier, and had 2% higher dressing-out percentage, 5·7 mm thicker fat and 5 mm2 larger area of m.longissimus thoracis than those on the slow-gaining regime.

Charolais-sired steers on both regimes had the fastest gain and were the first to reach slaughter weight. Limousin-sired steers raised on the fast-gaining regime had the highest dressing-out percentage, and the largest area of m. longissimus thoracis on both regimes. Hereford-sired steers had the thickest fat cover and the smallest area of m. longissimus thoracis. Little difference was found between the steers from Holstein and Ayrshire cows.

1. Ninety-six Large White fattening pigs, 8-10 weeks old at the beginning of the trial were used to study the effects of ultra-violet irradiation (22½ hours daily) with and without oxytetracycline supplements of the diet. All meal fed was fortified with vitamin D.

2. Under the conditions of this trial ultra-violet irradiation was without effect. Oxytetracycline supplementation resulted in significantly higher live-weight increases, lower age at slaughter and improved feed conversion.

3. No significant treatment differences were recorded for any of the carcass measurements.

4. Ultra-violet irradiation did not reduce the number of ‘thumping’ pigs nor the degree of lung damage by virus pneumonia, whereas ‘thumping’ was significantly less on the oxytetracycline treatments.

5. The results are discussed in relation to vitamin D requirements and the presence of virus pneumonia.

Peas (Pisum sativum) are a good source of protein for pigs (Saini and Batterham, 1989) and can be substituted for soyabean meal (Gatel and Grosjean, 1990). However, there is relatively little information on the true replacement value of peas in terms of energy and protein. The present study was undertaken to compare extracted, dehulled soyabean meal and a spring variety of peas (Solara) when used as the sole source of supplementary protein or in combination.

International field data suggest that up to one out of every four piglets dies before weaning. After accounting for stillbirths, crushing and piglets that die because they do not get enough to drink or are too weak to survive, most of the remainder die of scours. In the first week of life most scours are caused by Escherichia coli. Data have suggested that up to 50% of these scour deaths are caused by the K88 type E. coli, accounting directly for the deaths of about 150 thousand piglets per year in the U.K. and over 10 million worldwide.

Field observations have suggested that only some litters are affected while others remain healthy even though they are reared alongside litters with K88 scour. Similarly, it has been observed that the progeny from certain boars are more susceptible.

The welfare of domestic food animals has been defined by their state as regards their attempts to cope with their environment(Broom, 1986). Attempts made by the animals to cope can be successful or unsuccessful; unsuccessful attempts are defined as poor welfare. The assessment of animal welfare may be made, for example, ethological, endocrinological and immunological methods. Poor welfare has been associated with increased disease susceptibility; furthermore stress can cause immunosupression (reviewed by Kelley, 1980). Therefore, immune responses should indicate the welfare of an animal. An experiment was designed to assess immune responses as indicators of welfare of calves kept in different husbandry conditions.

During the last decade or more we have heard a great deal about progeny testing. Discussion has centred round three chief points. Under what conditions can selection by progeny testing lead to an increase in the rate of genetic improvement ? What method of testing and interpretation of results is most efficient and most practical ? How should the results be applied—that is in what way should the tested animals be used ?

In their paper reprinted herein (page 79) Johansson and Robertson have shown to what extent modern genetical theory can answer the second of these questions. It now remains for the executive agencies of livestock improvement to demonstrate the practical utility of the schemes they outline. We must wait some time, especially for slow-breeding animals like cattle, before the results of such a demonstration are available.

An optimum way of selecting animals is through a prediction of their genetic merit (estimated breeding value, EBV), which can be achieved using a best linear unbiased predictor (BLUP) (Henderson, 1975). Selection decisions in a commercial environment, however, are rarely made solely on genetic merit but also on additional factors, an important example of which is to limit the accumulation of inbreeding. Comparison of rates of inbreeding under BLUP for a range of hentabilities highlights a trend of increasing inbreeding with decreasing heritability. It is therefore proposed that selection using a heritability which is artificially raised would yield lower rates of inbreeding than would otherwise be the case.

Growth and carcass traits were measured in pigs grown from 25 to 90 kg live weight on barley stored and prepared in different ways. Some of the barley was prepared in the conventional manner by drying to a moisture concentration of 140g/kg before hammer-milling. The remainder of the barley was rolled after treating batches, containing 140, 180 and 240 g moisture per kg, with propionic acid. A total of 128 pigs was used at three centres.

There were no differences between the centres and no differences in the performance and carcass measurements of pigs given acid-treated and rolled, or untreated and milled barley, despite differences in physical form between the rolled and milled samples. When the intake of dry matter was equalized there was no apparent effect on the pigs of acid treatment of barley containing different amounts of moisture.

The availability of the vaccine Fecundin ® (Coopers Animal Health) could have far reaching effects on commercial lamb production in the UK. Immunisation with Fecundin is claimed to increase ovulation rate with a corresponding effect on subsequent lambing rate.

Trials in Australia, New Zealand and the UK have produced responses to immunisation in lambing percentage (lambs reared/100 ewes mated) ranging from −5% to +67%. The trial being reported set out to examine the effect of treatment with and without oestrus synchronisation in an upland flock of Scottish Blackface ewes being crossed with Texel rams and with a normal lambing percentage of around 130.

One hundred and sixty nine 1, 2 and 3 crop (2.5,3.5 and 4.5 year old) Scottish Blackface ewes were allocated in September 1984 between four treatments on the basis of age, liveweight and condition score.

The use of oestradiol-17β was evaluated in cereal-based beef production on 14 farms with 450 bulls. Half of the bulls were implanted subcutaneously in the ear with a silastic rubber implant containing 45 mg oestradiol-17β Representative bulls close to mean weight for each group were selected for slaughter on the same day at the end of the trial for carcass measurements. The remaining bulls were slaughtered at the farmers' discretion. Where possible, slaughter live weight (208 bulls), carcass weight (412) and European Economic Community carcass classification (353) were recorded. Implanted bulls had higher gains only in the first 3 months (+76 (s.e. 17) g/day; P < 0·001) and had heavier carcasses with the extra weight in the forequarter (+2·3 (s.e. 0·61) kg; P < 0·001), better carcass shape (+0·9 (s.e. 0·3) points; P < 0·01) and more subcutaneous fat in the thin flank (+1·3 (s.e. 0·6) g/kg; P < 0·05). Implanted bulls selected for slaughter by farmers were not slaughtered earlier, but killed out better (+0·7 (s.e. 0·3) g/kg; P < 0·05) and had heavier carcasses (+4·6 (s.e. 0·5) kg; P < 0·01) of better shape (+0·8 (s.e. 0·3) points; P < 0·05).

The use of zeranol was evaluated in cereal beef production on 15 farms with 385 bulls. Half received 36 mg zeranol which was repeated after 6 months. Forty-four bulls were selected for detailed carcass assessment as above. Implanted bulls had daily gains 0·06 (s.e. 0·01) kg greater (P < 0·001) than controls. Farmers chose to slaughter implanted bulls 8·3 (s.e. 3·8) days earlier (P < 0·05) at only marginally heavier weights (+4·8 (s.e. 3·1) kg; P = 0·08). More implanted bull carcasses were distributed in better shape and higher fat classes (P < 0·01). There were no significant differences in fore- and hindquarter and thin-flank tissue proportions. Oestradiol treatment marginally decreased testis weight in slaughtered bulls whereas zeranol treatment had no significant effect although epididymal weight was decreased in zeranol treated bulls. There were no clear effects of either treatment on testicular structure, but both oestradiol and zeranol caused a degree of disruption to the epididymal epithelium. Zeranol concentrations in treated animal tissues were not significantly different from those in control animals.

The primary aim of this study was to develop a FSH enzyme immunoassay (EIA) for the bovine species. The newly developed EIA was validated for FSH determination in bovine plasma by comparison with an existing bovine FSH radioimmunoassay. The EIA detected bovine FSH with a high sensitivity (0.1 ng/ml). Cross-reactivity of the EIA was 0.01% with bovine LH, 51% with ovine FSH, <0.1% with porcine FSH and <0.01% with equine FSH. Using this EIA on different time series of plasma in cows, we have confirmed the presence of a FSH pre-ovulatory peak at estrus, of periodic FSH fluctuations accompanying the waves of terminal follicular development, and of FSH pulses, mainly asynchronous with LH ones, in the peri-ovulatory phase of the cycle. In a second objective, the EIA was used to assess the role of FSH in regulating the development of ovarian follicles up to the small antral stage in young calves. To answer this question, six calves were submitted to weekly blood sampling during their first 3 months of life, and FSH changes were studied concomitantly to those of anti-Müllerian hormone (AMH), a well-established endocrine marker of the ovarian population of small antral follicles in cows. In the ovaries of 3-month calves, the population of 3 to 5 mm follicles contained the highest intra-follicular AMH amounts, and the number of 3 to 5 mm follicles on ovaries was closely correlated with AMH concentrations in the plasma of calves at this age (rs = 0.94). Before 3 months of age, only two out of six calves showed a clear postnatal FSH peak in plasma, and no correlation was found between plasma FSH and AMH concentrations. These results indicate that female calves undergo different patterns of FSH secretion and that postnatal activation of follicular growth up to the small antral stage appears independent and not directly related to circulating FSH levels.

Our objective was to genetically characterize post-weaning weight gain (PWG), over a 345-day period after weaning, of Brangus-Ibagé (Nelore×Angus) cattle. Records (n=4016) were from the foundation herd of the Embrapa South Livestock Center. A Bayesian approach was used to assess genotype by environment (G×E) interaction and to identify a suitable model for the estimation of genetic parameters and use in genetic evaluation. A robust and heteroscedastic reaction norm multiple-breed animal model was proposed. The model accounted for heterogeneity of residual variance associated with effects of breed, heterozygosity, sex and contemporary group; and was robust with respect to outliers. Additive genetic effects were modeled for the intercept and slope of a reaction norm to changes in the environmental gradient. Inference was based on Monte Carlo Markov Chain of 110 000 cycles, after 10 000 cycles of burn-in. Bayesian model choice criteria indicated the proposed model was superior to simpler sub-models that did not account for G×E interaction, multiple-breed structure, robustness and heteroscedasticity. We conclude that, for the Brangus-Ibagé population, these factors should be jointly accounted for in genetic evaluation of PWG. Heritability estimates increased proportionally with improvement in the environmental conditions gradient. Therefore, an increased proportion of differences in performance among animals were explained by genetic factors rather than environmental factors as rearing conditions improved. As a consequence response to selection may be increased in favorable environments.