A study was carried out to examine the relationship between silage intake and rumen degradability characteristics of silage. The dry matter (DM), neutral-detergent fibre (NDF), acid-detergent fibre (ADF), hemicellulose and nitrogen (N) degradability characteristics of 136 silages were determined using polyester bags in three rumen fistulated beef cross steers. The bags were incubated for 0, 6, 12, 24, 48 and 72 h. Intakes of these silages, by steers, were reported by Steen et al., 1998. The relationships between silage DM intake (g/kg metabolic live weight) and DM, fibre and N degradability characteristics of the silages were poor (R2 < 0·32). Degradability characteristics of the silages were highly negatively correlated with fibre concentration of the silages (R < –0·82) and highly positively correlated with the soluble N minus ammonia concentration (R < 0·77). Some of the degradability characteristics were highly correlated with organic matter digestibility, particularly the proportion of DM, fibre and N degraded after 72 h (R = 0·75 to 0·85). In view of the poor relationship between silage intake and degradability, the results of this study question the rôle of degradation characteristics of DM, fibre and N in the rumen on silage intake.

Thirty-seven Blackface wether sheep, ranging from birth to eighteen months of age, were used to derive the allometric relationship between carcass muscle and carcass bone.

The equation

log10 muscle (g) = 1·36 log10 bone (g)—0·804

fitted the data well. (r = 0·995, b = 1·36±0·05, Sy.x = 0·0595.)

The deviations from this equation had a coefficient of variation of 14% indicating that other factors may influence the relationship of muscle to bone.

It is suggested that the variable

log10M—1·36 log10 5 + 0·804

is independent of differences due to different stages of natural development and can be used to examine the effects of different treatments on the muscle: bone ratio. The constant applies to sheep only.

Expressions are given for the variance of estimates of breed differences for direct and indirect comparisons among foreign breeds, using either purebreds or crossbreds. These expressions allow for planned genetic relationships among the groups tested.

Computer tomography (CT) was evaluated as a method to predict body composition of live goats. Forty-one lactating goats were scanned. CT values (X-ray attenuation data) representing soft body tissues were summarized into 140 frequencies. By principal component analysis the 140 multicollinear frequencies were reduced to six orthogonal principal components at the loss of only 0·032 of the original variation.

Following scanning at four positions the goats were slaughtered, dissected and the data analysed. Seven compositional traits (water, protein and fat from the carcass and non-carcass parts, and total energy of the body) were regressed on live weight and the six principal components from each of five CT data sets (data from the four scan positions and pooled data) in a stepwise linear regression procedure. Models from the pooled data set were further evaluated in a cross-validation procedure. Compared with evaluation based on calibration only, a more simple and precise model was chosen as the best by this procedure.

After addition of CT variables in prediction equations already comprising live weight, cross-validation deviations were reduced by 0 for carcass water, 0 for carcass protein, 0·48 for carcass fat, 0·14 for non-carcass water, 0·23 for non-carcass protein, 0·73 for non-carcass fat, and 0·73 for total energy. These results show that CT is a valuable in vivo method for predicting body fat and energy, but less valuable for body water and protein.

An efficient algorithm for genomic selection of moderately sized populations based on single nucleotide polymorphism chip technology is described. A total of 995 Israeli Holstein bulls with genetic evaluations based on daughter records were genotyped for either the BovineSNP50 BeadChip or the BovineSNP50 v2 BeadChip. Milk, fat, protein, somatic cell score, female fertility, milk production persistency and herd-life were analyzed. The 400 markers with the greatest effects on each trait were first selected based on individual analysis of each marker with the genetic evaluations of the bulls as the dependent variable. The effects of all 400 markers were estimated jointly using a ‘cow model,’ estimated from the data truncated to exclude lactations with freshening dates after September 2006. Genotype probabilities for each locus were computed for all animals with missing genotypes. In Method I, genetic evaluations were computed by analysis of the truncated data set with the sum of the marker effects subtracted from each record. Genomic estimated breeding values for the young bulls with genotypes, but without daughter records, were then computed as their parent averages combined with the sum of each animal's marker effects. Method II genomic breeding values were computed based on regressions of estimated breeding values of bulls with daughter record on their parent averages, sum of marker effects and birth year. Method II correlations of the current breeding values of young bulls without daughter records in the truncated data set were higher than the correlations of the current breeding values with the parent averages for fat and protein production, persistency and herd-life. Bias of evaluations, estimated as a difference between the mean of current breeding values of the young bulls and their genomic evaluations, was reduced for milk production traits, persistency and herd-life. Bias for milk production traits was slightly negative, as opposed to the positive bias of parent averages. Correlations of Method II with the means of daughter records adjusted for fixed effects were higher than parent averages for fat, protein, fertility, persistency and herd-life. Reducing the number of markers included in the analysis from 400 to 300 did not reduce correlations of genomic breeding values for protein with current breeding values, but did slightly reduce correlations with means of daughter records. Method II has the advantages as compared with the method of VanRaden in that genotypes of cows can be readily incorporated into the Method II analysis, and it is more effective for moderately sized populations.

Four litters produced by father-daughter matings (back crosses) resulting in 35 animals with a theoretical inbreeding coefficient of 25% were typed with 21 independent informative markers. The differences between the two founder animals were estimated, based on the marker information, and it was found that the founder boar had higher genetic potential for proportion of lean meat and lower genetic potential for groivth than the founder sow. The proportion of the genome of each offspring which was identical by descent was investigated. On the basis of these markers the realized inbreeding was found to vary between 7 and 47%. The linear decrease in weight at days 1, 26 and 136, average daily gain and proportion of lean meat regressed on the realized inbreeding were estimated to 0·6 kg, 2·4 kg, 18 kg, 95 g/day and 15 g/kg, respectively. For weight at day 88 a corresponding linear increase of 11 kg was observed. The joint effect of founder differences and realized inbreeding were as expected negative and statistically significant for all growth traits.

A study was conducted to estimate the genetic relationship between weaning weight and milk yield in Nguni cattle. Milk yield data (n=125) were collected from 116 Nguni cows from Mara Research Station located in Limpopo Province and Loskop South Farm located in Mpumalanga Province using the weigh-suckle-weigh technique. Weaning weight data (n=19 065) were obtained from stud Nguni cattle from 146 herds distributed throughout South Africa. Estimates of (co)variance components for milk yield and weaning weight were calculated using PEST and VCE softwares. The average weaning weight, age of the calf at weaning and 24-h milk yield was 158.94 kg, 210 days and 5.25 kg/day, respectively. Heritability estimates for milk yield, direct and maternal weaning weight were 0.22±0.238, 0.47±0.039 and 0.25±0.029, respectively. Estimates of genetic correlations for milk yield and maternal weaning weight, milk yield and direct weaning weight, direct and maternal weaning weight were 0.97±0.063, −0.71±0.416 and −0.56±0.247, respectively. The results indicate that maternal weaning weight is genetically highly predictive of milk yield in Nguni cattle. Maternal breeding values for weaning weight could therefore be used as a selection criterion to improve milk yield in Nguni cattle.

The twinning rate of Finn × Awassi ewes in a breeding management system which included three breeding periods a year, namely, June, September and December-January, was studied in animals mated at their natural or induced oestrus.

A similar number of lambs per ewe lambing was obtained from the ewes mated either at the induced oestrus in June or September, or at their natural oestrus in December. A significant decrease was found in the twinning rate of the ewes mated in January after hormone treatment. The conception rate was highest in the ewes mated in December-January.

Great changes have been brought about in British farming by the war. Of these changes the most obvious as well as the most important have been, firstly, the conversion of large areas of grassland into arable to grow much needed human food crops, and secondly, the decline that has taken place in the numbers of all classes of farm livestock other than dairy cattle.

There are now welcome signs that the European war may soon be brought to a successful conclusion and the time is appropriate, therefore, for taking stock of British farming as a whole as well as of its component parts, in order to decide what developments are necessary to bring farming in this country into a sound and healthy state, so that it may yield its full profit to farmers themselves and to the nation as a whole.

It is now widely accepted that the subcutaneous implantation of stilboestrol or hexoestrol increases the rate of live-weight gain in lambs and cattle. In sheep it is generally considered that for a feeding period of up to 12 weeks a single implantation of hormone produces an adequate growth response. Perry et al.(1951), Stephens & Thompson (1952) and Bell et al.(1954) reported no advantage from repeated implantations during the experimental period. In a series of experiments at this Institute (Preston & Gee, 1957a) it has been noticed that the major part of the increased weight gain takes place during the first six weeks after hexoestrol implantation.

A system of feeding concentrates at a flat rate was compared with a step system in which the rate was reduced every 6 weeks. Each system was evaluated at either medium or high level concentrates. There were two trials involving 40 British Friesian cows for weeks 3 to 20 of lactation. The flat rate treatments were 71 (medium) and 9·3 kg dry matter (DM) per day (high) and corresponding step allocations were 8·8, 7·1 and 5·4 kg DM per day or 11·7, 9·3 and 7·0 kg DM per day. Silage was given to appetite. In trial 1 this was lucerne silage of moderate quality (metabolizable energy (ME) = 8·9 MJ/kg DM) and in trial 2 high quality grass silage (ME = 11·1 MJ/kg DM) was used.

In the comparison between systems of concentrate allocation, food intakes, milk production and live-weight change were similar in each trial. In the comparison between medium or high levels of concentrates, silage DM intakes were similar in trial 1 (7·1 v. 7·0 kg/day) but not in trial 2 (9·8 v. 8·7 kg·day, P < 0·05), and milk yields were lower in trial 1 (19·0 v. 21·4 kg/day, P < 0·001) but not in trial 2 (24·1 v. 25·2 kg/day). Milk composition was similar for medium and high concentrate intakes in both trials. Cows given the medium level of concentrates had higher live-weight losses than those given the high level in trial 1 (–58 v. –24 kg, P < 0·01) and trial 2 (–22 v. –kg). When concentrates were given at the medium level with moderate quality silage several cows had acetonaemia. Also, this feeding combination, especially when concentrates were given at a flat rate, reduced the proportion of cows which conceived within a limited breeding period.

At weaning at 3 months of age (week 1), 30 red deer hind calves were housed in six groups of five animals at a stocking density of 1·5 m2 per head and maintained in these groups for 4 weeks. At the start of week 5, all calves were immunized with ovalbumin (OVA). Fifteen calves, from three groups, selected at random, were transferred to individual pens which restricted visual and tactile contact with others (ISO) while the remaining animals were kept in their groups (GP). The behaviour, food intake, live-weight gain, antibody and lymphocyte responses in vitro to OVA and lymphocyte responses in vitro to the non-specific mitogen, concanavalin A (ConA), of all calves were assessed in each of weeks 5 to 9. Isolated calves had a lower mean live-weight gain than GP calves (P < 0·001), although there were no differences in food intake. Significantly more time was spent lying (P < 0·001) but less time feeding (P < 0·05) and self-grooming (P < 0·001) by ISO than by GP calves. There was no significant difference between ISO and GP calves in the cortisol response to an ACTH challenge test (10 i.u.) at week 11. Lymphocyte responses and antibody titres to OVA were lower in GP than in ISO calves at weeks 7 (P < 0·05) and 8 (P < 0·05), respectively. In contrast, GP calves had greater lymphocyte responses to the non-specific mitogen, ConA, in weeks 7 (P < 0·05) and 10 (P < 0·001) but not in week 9 compared with ISO calves. Differences in lymphocyte stimulation were attributed to the non-specific mitogenic nature of ConA. Factors such as agonistic interactions evident in group housing may have compromised the antibody and lymphocyte responses to OVA by GP calves but conversely the lack of social contact may have also suppressed behavioural activity in ISO calves.

Force-feeding was considered as a traditional high-efficiency approach to improve growth performance and accelerate fat deposition of Pekin ducks. However, force-feeding is a serious violation of international advocacy on animal welfare, because it can induce serious injuries to animals, such as damages to the digestive tract, effects on immunity and even severe oxidative stress. Therefore, it is urgent to stop force-feeding. The aim of this study was to determine the effects of force feeding on immune function, digestive function and oxidative stress in the mucosa of duodenum and jejunum of Pekin ducks. A total of 500 ducks were randomly divided into two groups. The control group was allowed to feed freely on a basal diet. The experimental group was force-fed by inserting a plastic feeding tube 8 to 10 inches long down the esophagus for 6 days. Compared with the control group, there was a significant (P<0.05) increase in serum diamine oxidase, d-lactic acid, endotoxin and corticosterone levels in the force-feeding group. The crypt depth in duodenum and jejunum showed significant differences (P<0.05) between the two groups and the intestinal villus epithelium cell was severely damaged in force-feeding group. Similarly, the activities of digestive enzymes as well as the levels of immune function in the duodenal and jejunal mucosa in the force-feeding group were significantly higher than the control group (P<0.05). However, there was a significant decrease in the superoxide dismutase, glutathione peroxidase and catalase levels with a marked increase in malondialdehyde level in duodenal and jejunal mucosa (P<0.05). In summary, at the end of the fattening period with force-feeding for 6 days, Pekin ducks experienced an adverse effect on the integrity of their duodenal and jejunal mucosa epithelium cell as well as their immune function and antioxidant capacity of Pekin ducks but also had improvement in digestive enzyme activities.

A feeding trial was carried out, using 180 pigs, to assess the effect on performance when intact male and female pigs were housed together in the same pens from 20 to 90 kg live weight. There were no significant differences in daily feed intake, rate of growth or feed: gain ratio between pigs from mixed-sex pens and pigs from single-sex pens. Carcass measurements indicated slightly leaner carcasses for intact male pigs whether housed in separate pens or together with female pigs, while female pigs likewise had a significantly higher dressing percentage.

Mortality to one year of age was studied in artificially-reared calves of Tharparkar, Sahiwal and Red Sindhi breeds together with Murrah buffaloes and Brown Swiss x Sahiwal and Brown Swiss x Red Sindhi. Data covered 6267 animals over the period 1952–71. There were significant breed differences with the Brown Swiss crosses and buffaloes suffering higher losses than the Zebu breeds. Age effects (0 to 1, 1 to 3, 3 to 6 and 6 to 12 months) showed that losses were greatest in the first month of life and declined thereafter. There were significant year effects but seasons (summer, monsoon and winter) showed no significant effects although a tendency to higher losses in winter did exist. Sex effects showed no differences. Pneumonia was the major cause of loss to 6 months accounting for 30 to 40% of deaths with scours and enteritis being the second most serious factor (15 to 35% of losses).

This work was designed to study the influence of parity (multiparous (MP, no. = 9) or primiparous (PP, no. = 10)) and feeding level (control diet (CD; 1·00) or restricted diet (RD; proportionately 0·70 of requirements) in a 2×2 factorial design on the utilization of exogenous glucose in the suckler anoestrous Charolais beef cow. Lack of ovarian activity was confirmed by low circulating progesterone concentrations measured in weekly blood samples taken after parturition. An injection of glucose (1·5 mmol/kg live weight) lasting 20 min was given 30 days and 50 days post partum. Blood samples were collected before and for 120 min after the start of the injection and plasma insulin, glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate and urea were measured. Although plasma glucose concentrations were not significantly different between treatment groups in the period immediately after the injection of glucose, CD PP animals had higher plasma insulin levels than CD MP animals (at 25 min: 596·4, 283·8, 435·1 and 309·6 pmol/l, P < 0·05 for groups PP CD, MP CD, PP RD and MP RD respectively). Plasma NEFA concentrations were initially higher in the RD groups compared with the CD groups but were reduced by the glucose injection (P < 0·001). However, the PP RD cows took longer to respond to the exogenous glucose compared with the MP RD cows (at 25 min: PP RD: 133·2 and MP RD: 57·5 eq/l, P < 0·05). In conclusion, suckler anoestrous PP cows appear to require higher plasma insulin levels than MP cows to metabolize exogenous glucose and underfed PP cows were slower to reduce plasma NEFA after glucose injection than underfed MP cows.

Lambs from Perendale, Merino × Perendale, Romney, Merino × Romney and Coopworth ewes, and Southdown and Suffolk sires were assigned to three groups. Groups received no treatment, nine weekly doses of 175 mg iron (Fe) per kg body weight or nine weekly doses of 175 mg zinc (Zn) per kg body weight. They were slaughtered 1 week after the last dose. Samples of m. longissimus were analysed for Fe and Zn concentration.

Muscle Zn concentration was greater for Southdown-sired lambs (85·5 mg/kg dried muscle) than for Suffolk-sired lambs (77·6 mg/kg; P < 0·01). Dam genotypes and the interaction of sire breed and dam genotype were not significant for Zn concentration. Heritability of muscle Zn concentration was estimated to be 0·92 (s.e. 0·48). Muscle Fe concentration showed a significant interaction between sire breed and dam genotype (P < 0·05). Heritability of muscle Fe was estimated to be 0·21 (s.e. 0·38). No significant interactions of either sire breed or dam breed × treatment were found.

Six experimental diets with similar contents of macronutrients (450, 300 and 70 g/kg dry matter of protein, carbohydrate and fat, respectively) and, therefore, total energy, hut differing in the composition of lipid component, were each given to three replicate groups of European eel. Different fat mixtures were used to formulate diets with different levels of fatty acids considered as essential for fish: linoleic (18: 2n6), linolenic (18: ЗпЗ) and highly unsaturated fatty acid (HUFA)n3, mainly EPA (20: 5n3) and DHA (22: 6n3). One tested diet contained low levels of all the three components, three diets had a high level of each one of these, the fifth diet contained high levels of both 18C fatty acids and, finally, a sixth diet incorporated simultaneously high amounts of 18: 2n6 and (HUFA)nЗ.

Dietary lipid composition did not significantly affect food intake or protein and fat apparent digestibility. However, growth and food efficiency were the best with the diet containing approximately 5 g/kg of both linoleic and linolenic acids. Although all groups increased their body fat content over the experiment, the fatty acid composition of total muscle lipids was rather insensitive to lipid dietary composition, perhaps due to the high body fat content of the eels prior to the experiment.