The objectives of the two experiments were to determine the respective effects and interactions of diet type (grass v. maize diets) and physical activity (grazing v. zero grazing) on lipogenic enzyme activities and adipose cell size in subcutaneous, perirenal and intermuscular adipose tissues and on plasma metabolites and hormones in Charolais steers. After weaning, the steers were assigned to two (Experiment 1, n = 24) or three (Experiment 2, n = 24) groups, with steers in Experiment 1 grazed grass or indoors maize-silage-fed and steers in Experiment 2 grazed grass, indoors cut grass- or indoors maize-silage-fed. Both experiments lasted for 23 months. All grass-fed animals were fed grass silage during the two winter seasons. During the two summer seasons, steers fed on grass were rotationally grazed on a perennial rye-grass pasture while steers fed on cut grass were fed indoors on freshly cut grass alone. Steers fed on maize silage were fed maize silage indoors during the entire experiment. All animals were reared for similar body weight and growth rates and slaughtered at the same age (31 to 32 months). Activities of lipogenic enzymes were significantly lower in the three adipose tissue sites of steers fed cut grass compared with maize silage, although there were less-marked effects in intermuscular adipose tissue. Plasma insulin and glucose concentrations were also lower in steers fed cut grass whereas plasma leptin concentration was similar. As body fat content was not affected by nutritional treatment, it is suggested that the decrease in potential lipogenic activity was associated with the nature of the diet and not to differences in available net energy. In other respects, grazed grass compared with eating cut grass did not affect lipogenic enzyme activities but decreased plasma leptin concentrations in the older steers and increased plasma non-esterified fatty acids and glucose concentrations without affecting adipose tissue weight and adipose cell size.

Lameness in dairy cattle can result in significant economic loss. High protein levels in the diet have been implicated as a cause of lameness, whilst trimming has been advocated as an effective preventative measure. This trial examined the effects of these two factors on locomotion, hoof measurements and incidence of lameness.

Forty eight autumn calving cows in a continuous design experiment, lasting from weeks 3 to 26 of lactation were allocated to 4 treatments: LT (161 g/kg DM crude protein in the total diet, hooves trimmed); LUT (161 g/kg DM, untrimmed), HT (198 g/kg DM, trimmed) and HUT (198 g/kg DM, untrimmed). The protein levels in the complete diet were adjusted by substituting barley for soya. Daily ME intakes were maintained at the same level for all treatments by adjusting the high protein diet intake to that of the low protein, which was offered ad libitum. The cows feet were shaped and trimmed to a toe length of about 7 cm, 4 months before calving. Cows were scored for their locomotion weekly on a scale of 1 to 5 high scores indicate lameness. Hoof shape, growth, wear and hardness were recorded every 8 weeks on the right hind claw.

The effect of grazing clover on ewes and lambs was studied using nitrogen-fertilized grass (G) and grass/white clover pastures (GC) containing proportionately 0·18 clover. Carcasses of lambs grazed on GC were significantly heavier than carcasses of lambs grazed on G pastures. An interaction with weaning occurred. Carcasses from lambs grazed on GC for 53 days post weaning were 2·3 kg heavier (F < 0·01) but lambs slaughtered at weaning had similar carcass weights. Diet had no effect on relative joint components of carcasses. The effect of clover in the diet on carcass weight was attributed to higher levels of protein retention.

Analysis of the fatty acid composition of intramuscular and subcutaneous and perirenal lipids indicated small but significant effects of diet. Lean tissue lipids of lambs grazing clover showed significant increases in C18:2 and reduced C20: 5 fatty acids. In tissue fats there were small increases in C14:0, C16:0 and C18:2 with reduced C18:1 content.

Twin suckled lambs grazing GC for 94 days from turn-out in early April showed increased live-weight gain over lambs on G of 336 v. 287 g/day (s.e.d. 84; P < 0.001). Post weaning live-weight gain of lambs was 173 and 221 g/day on G and GC respectively. Sward height was maintained at 5.18 and 5.24 (s.e.d. 0.075) cm on G and GC paddocks by adjusting ewe numbers. GC pastures carried proportionately 0.82 of the stock on G pastures but output of lamb was similar at 1289 and 1247 kg/ha for G and GC respectively.

Results showed that the production penalty of lower stocking rate associated with grass/clover v. grass fertilized with 190 kg nitrogen per ha was ameliorated by higher lamb live-weight gain and carcass weight without change in joint composition or nutritionally significant change in fatty acid composition of carcass tissues.

Fourteen Large White female pigs were mated at about 6 months of age and 90 kg live weight. Three of them gave birth to very small litters and were slaughtered a week after parturition at an average live weight of 166 kg. From the other 11 females 6-week-old litters with average an of 8-8 piglets were weaned. Twenty-four days after weaning the mothers, averaging 152 kg live weight, were slaughtered. Performance was compared with that of unmated females slaughtered at 90 or 130 kg live weight. After subtracting the amount of feed used normally for the production of weaned litters from the total feed consumption of the 14 females which farrowed, the feed intake per 1 kg live-weight gain was 3·67 kg, as compared with 3·43 kg and 4·46 kg in the groups slaughtered at 90 or 130 kg live weight, respectively. The average daily protein deposition in the 14 females together with their litters was 119·6 g, compared with 104·1 and 81·4 g in the control groups.

BW of replacement heifers is rarely measured on commercial farms, making it difficult to evaluate the success of management practices related to calf growth. Our aims were to describe variability among commercial farms in Holstein heifer BW, determine how BW differences varied with management and propose a method of estimating calf growth based upon single measurement. Heart girth circumference was used to estimate BW of 576 heifers 48 to 70 weeks of age on 33 different farms (on average 11±6 heifers/farm) in British Columbia, Canada. Regression analysis showed a linear relationship of BW with age (BW (kg)=116+5×age (weeks)). Residuals from this regression were averaged across heifers within each farm to identify farms where heifers were heavier or lighter than would be predicted on the basis of their age; farm average residuals ranged from −54 to 72 kg. Farms with heifers showing the highest residual BW also had the highest rates of gain for pre-weaned calves. These results indicate that farms able to rear faster growing calves before weaning were also rearing faster growing heifers at breeding, and suggest that management of milk-fed calves is a particularly important component of replacement heifer management.

The growth and carcass data were determined for pigs reared on two creep rations to different weights, and subsequently fattened with and without an antibiotic.

Pigs weaned at a ‘standard’ weight of 43·8 lb. at 56 days of age grew more quickly over the range 120 to 210 lb. live-weight than pigs weighing 51·0 lb. at weaning. Both groups were fed according to a fixed scale related to live-weight. Heavy weaners growing slowly in the later stages had slightly thicker backfat measurements, indicating that they were at a more advanced stage of physiological development than the light weaners.

The presence of antibiotic in the fattening ration caused no significant difference in growth rate or carcass measurements, but there were significant interactions between weaning weight and presence or absence of antibiotic in the fattening ration for length of carcass, and between sex and presence or absence of antibiotic for the traits of age at 70 lb. live-weight, carcass length and depth of mid-backfat.

Weaning weight and rate of gain from 70 to 120 lb. live-weight were significantly and positively related to carcass length.

It is concluded that further studies of the growth curve of the pig are required to determine the scope and importance of compensatory growth, and the interaction of growth rates in the different phases of the pig's life and their relationships to carcass traits.

Three experiments were carried out in which the level of feed intake of pigs growing from approximately 30 to 90 kg was alternately raised and lowered, using different amplitudes and time-periods. Within each experiment, the total feed intake and the length of the experimental period were the same for all treatment-groups.

The two amplitudes which were examined were 112%–88% and 125 %–75% of standard scales of feeding. The time-periods between switches to the alternate level were 1, 3, 7 or 14 days. The impact of the fluctuations in feed intake on overall performance and carcass composition was either trivial or small, and in no case exceeded 5% for any one measurement. It is concluded that fluctuations in feed intake occurring in practical situations will have only trivial effects on performance, provided that pigs receive similar amounts of feed in the same overall period of time.

High-density single nucleotide polymorphism (SNP) platforms are currently used in genomic selection (GS) programs to enhance the selection response. However, the genotyping of a large number of animals with high-throughput platforms is rather expensive and may represent a constraint for a large-scale implementation of GS. The use of low-density marker (LDM) platforms could overcome this problem, but different SNP chips may be required for each trait and/or breed. In this study, a strategy of imputation independent from trait and breed is proposed. A simulated population of 5865 individuals with a genome of 6000 SNP equally distributed on six chromosomes was considered. First, reference and prediction populations were generated by mimicking high- and low-density SNP platforms, respectively. Then, the partial least squares regression (PLSR) technique was applied to reconstruct the missing SNP in the low-density chip. The proportion of SNP correctly reconstructed by the PLSR method ranged from 0.78 to 0.97 when 90% and 50%, respectively, of genotypes were predicted. Moreover, data sets consisting of a mixture of actual and PLSR-predicted SNP or only actual SNP were used to predict genomic breeding values (GEBVs). Correlations between GEBV and true breeding values varied from 0.74 to 0.76, respectively. The results of the study indicate that the PLSR technique can be considered a reliable computational strategy for predicting SNP genotypes in an LDM platform with reasonable accuracy.

A study was made of some aspects of reproduction in the Nungua Black Head and the Ghanian variety of the West African Dwarf sheep. The gestation period of the two breeds was similar: 150 and 148 days respectively. Ewes mated in August and September tended to have slightly longer gestation periods than those mated in March. The mean birth weights were 2·2 kg in the Nungua Black Head and 13 kg in the West African Dwarf. Type of birth affected the weight of lambs at birth. The Nungua Black Head had no triplets, 0·132 twins and 0·868 singles. The West African Dwarf was more prolific: 0·402 singles, 0·557 twins and 0·041 triplets. The weight advantage of the Nungua Black Head lambs at birth was maintained to weaning and they also had better survival rates. The adjusted 12-week weaning weights averaged 9·8 and 5·8 kg respectively for the Nungua Black Head and West African Dwarf. What the West African Dwarf lost in individual weight it appeared to make up in numbers so that, when the breeds were compared in terms of kg of lamb weaned per ewe mated, there was no significant difference between them.

Seventy-two Large White × (Large White × Landrace) weaner pigs in each of three experiments were scale-fed diets containing 850 g barley per kg which had been processed by either cold rolling (R) or grinding through 1-56 mm (O) or 468 mm (T) screens. In experiments 1 and 2 barley (0-868 dry matter) was used and group feeding was practised for 55 and 100 days respectively. In experiment 3 barley (0-838 dry matter) was used and individual feeding was practised for 107 days. In experiment 1 gastric pH was recorded at slaughter. In all experiments the stomachs of all pigs were examined for gross and histological abnormalities.

In experiments 1 and 2 growth rates and efficiencies of feed conversion were not significantly different for pigs fed the R-, O- and T-based diets. In experiment 1 the pH in the pylorus, but not in the fundus, was significantly higher in pigs fed the O-diet compared with the T-diet, and on the T-diet compared with the R-diet. Growth rates and efficiencies of feed conversion in experiment 3 were significantly poorer in pigs fed the R-diet compared with the T-diet, and on the T-diet compared with the O-diet. In experiment 1 one pig from each of the three diets showed hyperplastic changes in the pars oesophagea of the stomach. In experiment 2 no gastric abnormalities were found, but bile staining was present in the pyloric zone of one pig fed each of the three diets. In experiment 3 hyperplastic lesions of the pars oesophagea (and bile staining) were present in 19 (14), 10 (7) and 4 (1) pigs fed diets O, T and R respectively.

Twenty-six groups of four or eight pigs of mean initial weight 23·2 kg and mean age 84 days were exposed to environmental temperatures of 8, 12, 16 or 20°C under still-air conditions (wind-speed = 0·1 m.s−1) or of 12CC with wind-speeds of 0·45 or 0·8 m.s−1. The animals were fed at a fixed level close to three times their maintenance requirement, with water ad libitum, and were weighed weekly over a 7-week period. Variation in temperature between groups from 8 to 20°C had no significant effect on weight gain, but increasing wind-speed to 0·8 m.s−1 at 12°C resulted in reduced weight gain.

This study investigated effects of roasted or extruded oilseed supplementation ranging in n-6/n-3 ratios from 0.3 to 5.0 on the fatty acid composition and expression of delta-5 desaturase (Δ5d) and Δ6-desaturase (Δ6d) protein in commercial steer cheek (m. masseter) and diaphragm (pars costalis diaphragmatis) muscles. In general, the n-6/n-3 ratio of the diet had a subsequent effect on the muscle n-6/n-3 ratio (P < 0.05), with muscle 18:2n-6 and 18:3n-3 content relating to proportion of dietary soya bean and linseed (P < 0.01). Compared with canola, pure linseed and soya bean diets reduced 14:1c-9 and 16:1c-9 (P < 0.05) but increased 18:1t-11 and c-9,t-11 conjugated linoleic acid (CLA) content (P < 0.01). Oilseed processing had a minor influence but extruded oilseeds increase 18:1t-11 and c-9,t-11 CLA compared with roasted (P < 0.05). Polar lipid 18:3n-3 and n-3 long-chain polyunsaturated fatty acid (LC, ⩾20 carbons PUFA) derivative content increased in relation to dietary linseed supplementation in the diaphragm (P < 0.01), whereas only 18:3n-3 was increased in the cheek (P < 0.01). Protein expression did not differ between diets; however, in each muscle the Δ5d protein expression had a stronger association with the desaturase products rather than the precursors. The relationship between Δ5d protein expression and the muscle LC n-6/n-3 ratio was negative in both muscles (P < 0.05). The relationship between Δ6d protein expression and the LC n-6/n-3 ratio was positive in the cheek (P < 0.001) and negative in the diaphragm (P < 0.05). In conclusion, diet n-6/n-3 ratio affected muscle 18:2n-6 and 18:3n-3 deposition, whereas the Δ5d and Δ6d protein expression had some influence on the polar lipid LC-PUFA profile. Results reaffirm that processed oilseeds can be used to increase the proportion of fatty acids potentially beneficial for human health, by influencing the formation of LC-PUFA and reducing the n-6/n-3 ratio.

Data from 5270 lactation records of 1380 cows sired by 132 bulls and recorded from 1962 to 1977 were analysed. Statistical analyses, using least squares and maximum likelihood methods, showed significant effects for genetic group, age of cow, month and year of calving, and lactation length. Overall mean milk yield was 2780 kg (CV = 0·31) with mean lactation length of 281 days. Maximum production occurred in the fifth lactation (104 or 105 months of age at calving) with a yield of 1·3 times that of the first lactation. Repeatability estimated by intraclass correlation was 0·40 (s.e. 0·03). Heritability estimated from paternal half-sib correlation was 0·16 (s.e. 0·06). Overall results were very similar to those obtained from research with European breeds in temperate areas.

Optimal designs are given for estimating some of the genetic parameters needed to describe a population of breeds when testing facilities are limited and the number of breeds to be tested is potentially large. The best design for estimating the relative proportion of genetic variation within and between breeds is to have a large number of breeds, a few sires per breed, and a few offspring per sire, the total number of animals per breed being of the order of 10 to 20.

Selection work with the Rhode Island Red breed, involving the extensive collection of records, was first started at Wye College in 1948. Since that time the methods of selection employed have changed substantially in the light of the experience gained and the scheme, as it is operated at present, is shown diagrammatically in Fig. 1.

Sixty full-sister groups are recorded from first egg to the end of November. At least three full brothers of each of these sister groups.

Blood samples from 262 Polish Red Cattle, 9 Danish Red Cattle and 123 cattle produced by crossing were examined for the presence of 45 erythrocyte antigenic factors.

The frequencies of most of the factors are given and estimates are made of the appropriate gene frequencies within the Polish Red breed as a whole.

Segregation of 42 B alleles was observed of which 9 have not previously been reported. The H′ factor hitherto recorded as marking an independent system is assigned to the SU system on genetical grounds and renamed S2.

It is concluded from the blood group data that the Polish Red breed has signs of a genetic relationship with Holstein-Friesian, Brown Swiss and Guernsey breeds but the relationship with the Danish Red breed is closer. The existence of the new alleles distinguish the Polish Red breed of cattle from all others investigated.

Reproductive biotechnology such as in vitro fertilization, the creation of transgenic animals or cloning by nuclear transfer depends on the use of fully grown, meiotically competent oocytes capable of completing meiotic maturation by reaching the stage of metaphase II. However, there exists only a limited quantity of these oocytes in the ovaries of females. In view of their limited number, growing oocytes without meiotic competence represent a possible source. The mechanisms controlling the acquisition of meiotic competence, however, are still not completely clear. A gas with a short half-life, nitric oxide (NO), produced by NO-synthase (NOS) enzyme can fulfill a regulatory role in this period. The objective of this study was to ascertain the role of NO in the growth phase of pig oocytes and its influence on the acquisition of meiotic competence with the help of NOS inhibitors, NO donors and their combinations. We demonstrated that the selective competitive iNOS inhibitor aminoguanidine and also the non-selective NOS inhibitor l-NAME block meiotic maturation of oocytes with partial or even full meiotic competence at the very beginning. NOS inhibitors influence even competent oocytes in the first stage of meiotic metaphase. However, blockage is less effective than at the beginning of meiotic maturation. The number of parthenogenetically activated competent oocytes greatly increased in a pure medium after inhibitor reversion. A large quantity of NO externally added to the in vitro cultivation environment disrupts the viability of oocytes. The effectiveness of the inhibitor can be reversed in oocytes by an NO donor in a very low concentration. However, the donor is not capable of pushing the oocytes farther than beyond the first stage of meiotic metaphase. The experiments confirmed the connection of NO with the growth period and the acquisition of meiotic competence. However, it is evident from the experiments that NO is not the only stimulus controlling the growth period.

There are no estimates of the heritability of phenotypic udder traits in suckler sheep, which produce meat lambs, and whether these are associated with resilience to mastitis. Mastitis is a common disease which damages the mammary gland and reduces productivity. The aims of this study were to investigate the feasibility of collecting udder phenotypes, their heritability and their association with mastitis in suckler ewes. Udder and teat conformation, teat lesions, intramammary masses (IMM) and litter size were recorded from 10 Texel flocks in Great Britain between 2012 and 2014; 968 records were collected. Pedigree data were obtained from an online pedigree recording system. Univariate quantitative genetic parameters were estimated using animal and sire models. Linear mixed models were used to analyse continuous traits and generalised linear mixed models were used to analyse binary traits. Continuous traits had higher heritabilities than binary with teat placement and teat length heritability (h2) highest at 0.35 (SD 0.04) and 0.42 (SD 0.04), respectively. Udder width, drop and separation heritabilities were lower and varied with udder volume. The heritabilities of IMM and teat lesions (sire model) were 0.18 (SD 0.12) and 0.17 (SD 0.11), respectively. All heritabilities were sufficiently high to be in a selection programme to increase resilience to mastitis in the population of Texel sheep. Further studies are required to investigate genetic relationships between traits and to determine whether udder traits predict IMM, and the potential benefits from including traits in a selection programme to increase resilience to chronic mastitis.

The present study examined the possibilities and consequences of selecting pigs for reduced aggression and desirable maternal behaviour. Data were recorded from 798 purebred Large White gilts, with an age of 217±17.7 (mean±SD) days, which were observed at mixing with unfamiliar conspecifics. The reaction of the sows towards separation from their litter was assessed for 2022 litters from 848 Large White sows. Sows’ performance during their time in the farrowing unit was scored based on the traits farrowing behaviour (i.e. need of birth assistance), rearing performance (i.e. litter quality at day 10 postpartum (pp)), usability (i.e. additional labour input during lactation period e.g. for treatments) and udder quality of the sow (i.e. udder attachment). For agonistic behaviour, traits heritabilities of h2=0.11±0.04 to h2=0.28±0.06 were estimated. For the sow’s reaction towards separation from her litter low heritabilities were found (h2=0.03±0.03 for separation test on day 1 pp and h2=0.02±0.03 for separation test on day 10 pp). Heritabilities for lactating sow’s performance (farrowing behaviour, rearing performance, usability of the sow and udder quality) in the farrowing unit ranged from h2=0.03±0.02 to h2=0.19±0.03. Due to these results it can be assumed that selection for these traits, for example, for udder quality or reduced aggression, is possible. Antagonistic associations were found between separation test on day 1 pp and different measures of aggressiveness (rg=−0.22±0.26 aggressive attack and rg=−0.41±0.33 reciprocal fighting). Future studies should determine economic as well as welfare-related values of these traits in order to decide whether selection for these traits will be reasonable.

Twenty-one Finnish Landrace × Polled Dorset Horn female sheep approximating 8 months old were individually penned from 3 to 4 weeks after mating until parturition. They were allocated to one of three diets containing either 12·3, 14·1 or 16·5% crude protein and 2·1 Meal metabolizable energy per kg dry matter, offered at a level of 85 g/kg W0·75 per day. A series of nitrogen balance trials was carried out on all lambs during the last 100 days of gestation.

The mean age at parturition was 382 days and the mean litter size 1·52. The live-weight gain (mean value 152 g/day) was not significantly affected by the level of protein intake. There was a tendency (005 < P < 0·10 for singletons) for lamb birth weight to decrease and the body-weight change of the dam to increase with increasing protein concentration in the diet. There was a significant linear increase in nitrogen retention both with stage of gestation and level of protein intake.

The partition of nitrogen between the foetal and maternal body is discussed in relation to the estimated nitrogen content of the maternal live-weight gain.