A comparison was undertaken of 85 Holstein × Friesian (HF) and 84 Friesian (F) steer carcasses that had been produced on three production systems. These were: intensive barley beef (BB); grass/cereal 18 month; and 24 month forage system. On each system, HF steers were heavier at slaughter (over all systems, 476·5 v. 453·3 kg ***) and had a lower killing-out proportion (512 v. 521 g/kg ***), which resulted in higher carcass weights (243·5 v. 235·9 kg **). Steers were slaughtered on reaching a standard degree of finish (equivalent to European Economic Community fat-class 3), provided that they had attained a minimum live weight. There were no significant differences in carcass fat class (3·23 v. 3·35) but HF had poorer carcass conformation classification (2·62 v. 3·21 ***). Of the HF carcasses, 60·4% were rejected on conformation for Beef Premium Scheme payments and only 29·0% of the F carcasses were rejected (P < 0·001): a considerable and unmerited financial penalty. Objective carcass measurements showed HF to have longer sides (1257 v. 1233 mm ***), longer legs (812 v. 790 mm ***) and deeper forequarters (420 v. 402 mm ***). These differences remained when dressed carcass weight and sample-joint fat proportion were taken as covariates. Comparison of the weight-adjusted carcasses showed the HF to have reduced rump (P < 0·001) and loin thickness (P < 0·05). No other consistent effects were seen for carcass measurements, subjective scores or colour attributes. Dissection of the 7th t o 9th rib joint, as a predictor of carcass composition, revealed no significant overall differences in proportions (g/kg) of muscle (571 v. 567), bone (219 v. 219) or fat (206 v. 212). The implications of carcass value of the above findings are discussed.

A 3 X 2 factorial experiment was conducted to investigate the interactions between lactofeed 70 (LF70) (860 g/kg whey permeate, 140 g/kg soya-bean meal; Volac International, UK) and soya-bean meal (SBM) or dried skim milk (DSM) in piglet diets. Three hundred and thirty-six piglets were selected after weaning at 21 days with an initial live weight of 6-35 kg. They were blocked on the basis of live weight and within each block assigned to one of six dietary treatments. The pigs were offered the following starter diets : (1) 300 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (2) 200 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (3) 100 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (4) 300 g/kg LF70 with 325 g/kg DSM; (5) 200 g/kg LF70 with 325 g/kg DSM; (6) 100 g/kg LF70 with 325 g/kg DSM. The starter diets were offered for 25 days. Following this, a weaner diet (14 g/kg lysine, 14-5 MJ/kg digestible energy) was given for a period of 12 days. There was a significant interaction between LF70 level and protein source on average daily gain (ADG P < 0.001) and food conversion ratio (FCR P < 0.05) during the starter period. There was a linear increase in ADG and a linear improvement in FCR with increasing LF70 levels in diets with SBM. However, there was a linear decrease in ADG with increasing LF70 levels in diets with DSM. There was a significant interaction (P < 0.001) between LF70 level and protein source on average daily food intake (ADFI) during the starter period. At high LF70 levels, the inclusion of DSM reduced ADFl compared with SBM. However, there was no difference between DSM and SBM at the medium and low LF70 levels. There was a significant interaction between LF70 level and protein source in organic matter digestibility (OMD) (P < 0.01) and gross energy digestibility (GED) (P < 0.01). The pigs offered diets containing DSM had a significantly lower OMD and GED at low LF70 levels compared with pigs offered diets containing SBM. However, the inclusion of DSM had no significant effect on OMD or GED at the medium and high LF70 levels. There was a quadratic response in nitrogen digestibility (ND) with increasing concentrations of LF70 (P < 0.05). There was an increase in ND to 200 g/kg LF70 inclusion, however there was no further increase in ND above 200 g/kg LF70 inclusion. In conclusion, increasing the inclusion of lactofeed from 100 g/kg to 300 g/kg in starter diets where soya-bean meal comprised the principle protein source improved food efficiency and increased daily gain and daily food intake when compared with diets where dried skim milk comprised the principle protein source.

Amino acids stimulate the growth rate and growth yield of ruminal micro-organisms, but the basis of this stimulation, in terms of amino acids which most limit growth, has never been fully established. Here, for the first time, a deletion approach was investigated using in vitro incubations of mixed ruminal micro-organisms supplied with a mixture of xylose, starch and cellobiose as energy sources and ammonia plus a complete amino acids mixture or mixtures with a single amino acid omitted as nitrogen sources, enabling the evaluation of the impact on ruminal fermentation of the deletion of a single amino acid from a complete amino acids mixture. Significant effects (P < 0·05) on total gas production were observed after 10 h of incubation when glutamate, glutamine, isoleucine, leucine, phenylalanine, serine, tryptophan or tyrosine were deleted from the amino acids mixture. The only significant effect of an amino acid deletion on volatile fatty acid production at 10 h was with serine (P < 0·05), although the effect of omitting others, including arginine, isoleucine, leucine and phenylalanine, approached significance (P < 0·01). The removal of leucine caused a 0·09 decrease in growth yield (P < 0·05); no other deletion affected the yield significantly (P > 0·05). Net gas production for each treatment was calculated by subtracting gas production in the absence of carbohydrates from gas production in their presence, thus eliminating gas production from amino acids from the values. At all times up to 10 h, the most significant effects on net gas production were found when serine, leucine, or the aromatic amino acids were omitted from the amino acids mixture. Thus, the deletion approach confirmed that no single amino acid limits ruminal fermentation more than any other, although a few, principally phenylalanine, leucine and serine, have a particularly significant rôle in the ruminal fermentation rate of soluble, rapidly degraded materials and/or microbial growth efficiency.

It is important to identify molecular candidates involved in morphological and functional changes in the female reproductive system. We have discovered several candidate genes that were significantly altered in chick oviducts by exogenous estrogen and those candidates included dexamethasone (DEX)-induced RAS-related protein 1 (RASD1). RAS-related protein 1, a member of the Ras family of monomeric G proteins, is involved in various cellular processes including cell growth, proliferation and differentiation, as well as a cell-signaling protein regulating hormonal actions. Although the RASD1 gene was first identified as a DEX (a corticosteroid) inducible gene, there is evidence that it is also an estrogen-responsive gene. However, hormone-mediated expression and biological functions of RASD1 in the avian female reproductive system are poorly understood. Therefore, we tested the hypothesis that RASD1 may be involved in the development and remodeling of the chicken reproductive system as an estrogen-responsive gene. Here we demonstrate differential expression of RASD1 gene and candidate microRNAs (miRNAs) targeting chicken RASD1 transcripts in chicken oviducts in response to diesthylstilbestrol (DES, a synthetic non-steroidal estrogen) and the estrogen-mediated molting process. Result of the present study indicated that expression of RASD1 messenger RNA (mRNA) increased in the developing oviducts of chicks treated with DES, particularly in the glandular (GE) and luminal (LE) epithelia of the magnum and the shell gland. Also, during induced molting by zinc feeding, RASD1 expression changed in concert with changes in concentrations of estrogen in blood of laying hens. Our results revealed that expression of RASD1 mRNA decreased as the oviduct regressed and then increased as the oviduct underwent re-growth and recrudescence in hens. Furthermore, RASD1 mRNA was expressed predominantly in GE and LE of the oviduct of laying hens during regeneration of the oviduct after induced molting, but not during the period of regression of the oviduct during molting. In addition, the relative expression of candidate miRNAs (miR-30a-5p, miR-30b-5p, miR-30c-5p and miR-30d) regulating RASD1 transcripts changed in response to estrogen stimulation of chick oviducts. These results indicate that transcription of the RASD1 gene and miRNAs regulating post-transcriptional aspects of expression of RASD1 are modulated by estrogen which is critical for growth, development, remodeling and maintenance of function of the chicken oviduct.

Dietary fatty acid (FA) composition has an impact on human health. There is an increasing request from consumers for healthier food and pork industry must respond to it without worsening performance and the technological properties of pork products. The inclusion of genetic markers for carcass FA composition in pig selection schemes could be a useful tool to reach the right balance between unsaturated and saturated FAs to satisfy market demands. With the aim of finding genomic regions associated with porcine backfat FA composition, a genome-wide association study was performed on 798 Italian Large White pigs genotyped using Illumina PorcineSNP60 k. The strongest associations with backfat contents of palmitic, palmitoleic, oleic, medium-chain and long-chain FAs were found for the Sus scrofa chromosome (SSC) 8 region located at 119 to 122 Mb, where the gene ELOVL FA elongase 6 is mapped. Palmitic, palmitoleic, stearic and oleic acid contents were also found associated with SSC14, in particular with the genomic region at 121 to 124 Mb, where stearoyl-CoA desaturase Δ9 gene lies. On the other hand, the genomic regions associated with backfat contents of arachidic, arachidonic, n-6 and n-3 FAs showed to harbour mainly genes involved in dietary lipids and carbohydrates digestion, absorption and utilisation. To our knowledge, this is the first study performed in Large White pigs identifying markers and genomic regions associated with backfat FA composition. The results validate in Large White some associations previously detected in other pig breeds and indicate the involvement of distinct metabolic pathways in the deposition pattern of essential and non-essential FAs.

The growing request for healthier fatty acid composition of animal products is raising the necessity of a deeper knowledge of the main factors controlling fatty acids storage in muscle and backfat. Perilipin (PLIN) 5, and the whole Perilipin family, seem to play a crucial role in the regulation of lipids deposition as code for proteins coating intracellular lipid droplets surface. Nevertheless, the knowledge of these genes in pig is still incomplete. The present research was aimed at investigating in different pig breeds the PLIN5 gene, analysing its expression level and the associations of the variability in its downstream gene region with pork meat and carcass quality traits. Moreover, the PLIN5 protein localisation in porcine skeletal muscle was investigated through immunofluorescence, resulting to be widespread in Semimembranosus muscle (SM) myofibers. The identified single nucleotide polymorphism (SNP) rs327694326 (NC_010444.4:g.74314701T>C) located in PLIN5 downstream region was analysed in different pig populations, represented by 512 Italian Large White (ILW) pigs, 300 Italian Duroc (IDU) samples, 100 Italian Landrace, 100 Pietrain and 60 pigs belonging to three Italian native breeds (20 samples of Cinta Senese, 20 Calabrese and 20 Casertana pigs). The C allele was found in ILW, IDU and Pietrain pigs. In ILW pigs this SNP showed results indicating a possible association with oleic and cis-vaccenic fatty acid contents in backfat tissue. Furthermore, as PLINs are known to regulate lipases activity, we tested if the rs327694326 SNP was associated with differences in Hormone-sensitive lipase (LIPE) gene expression levels. In SM of ILW pigs, PLIN5 C allele was associated with significantly lower LIPE transcription levels than T allele (P=0.02 for Student’s t test of TT v. CT samples, P<0.0001 for TT v. CC pigs), whereas in IDU breed no significant difference was noticed in LIPE transcription levels between TT and TC animals. The results may suggest that variations in the PLIN5 sequence may be linked to LIPE expression through a still poorly known regulative molecular process.

Crossbreeding of Holstein–Friesian dairy cows with both early maturing (e.g. Aberdeen Angus (AA)) and late maturing (e.g. Belgian Blue (BB)) beef breeds is commonly practised. In Ireland, genetic merit for growth rate of beef sires is expressed as expected progeny difference for carcass weight (EPDCWT). The objective of this study was to compare the progeny of Holstein–Friesian cows, sired by AA and BB bulls of low (L) and high (H) EPDCWT for performance and carcass traits. A total of 118 spring-born male progeny from 20 (9 AA and 11 BB) sires (8 L and 12 H) were managed together from shortly after birth to about 19 months of age. They were then assigned to one of two mean slaughter weights (560 kg (light) or 620 kg (heavy)). Following slaughter, carcasses were graded for conformation class and fat class, the 6th to 10th ribs joint was dissected as an indicator of carcass composition, and samples of subcutaneous fat and musculus longissimus were subjected to Hunterlab colour measurements. A sample of m. longissimus was also chemically analysed. Slaughter and carcass weights per day of age for AAL, AAH, BBL and BBH were 747, 789, 790 and 805 (s.e. 10.5) g, and 385, 411, 427 and 443 (s.e. 4.4) g, respectively. Corresponding carcass weight, kill-out proportion, carcass conformation class (scale 1 to 5) and carcass fat class (scale 1 to 5) values were 289, 312, 320 and 333 (s.e. 4.0) kg, 516, 522, 542 and 553 (s.e. 3.5) g/kg, 2.5, 2.4, 3.0 and 3.1 (s.e. 0.10), and 3.4, 3.5, 2.9 and 2.8 (s.e. 0.11). There were few breed type × genetic merit interactions. Delaying slaughter date increased slaughter weight, carcass weight and all measures of fatness. It also reduced the proportion of carcass weight in the hind quarter and the proportions of bone and muscle in the ribs joint. None of these effects accompanied the increase in carcass weight due to higher EPDCWT. It is concluded that BB have superior production traits to AA. Selection of sires for higher EPDCWT increases growth rate, kill-out proportion and carcass weight of progeny with little effect on carcass or muscle traits. The extra carcass weight due to higher EPDCWT is more valuable commercially than a comparable carcass weight increment from a delay in slaughter date because it comprises a higher proportion of muscle.

The international Brown Swiss cattle population pedigree was studied to measure genetic variations and to identify the most influential animals. Twenty-two countries provided pedigree information on 71 497 Brown Swiss bulls used for artificial insemination (AI). The total number of animals with the pedigree is 181 094. The mean inbreeding coefficient for the pedigree population was 0.77%. There was, in most cases, an increase in the mean inbreeding coefficient, with the highest value at 2.89% during the last 5-year period (2000 to 2004). The mean average relatedness for the pedigree population was 1.1%. The effective population size in 2004 was 204. There was notable variation between average generation intervals for the four parental pathways. The longest average generation interval, at 8.73 years, was observed in the sire–son pathway. The average generation interval for the whole population was 6.53 years. Most genetically influential individuals were sires. The highest contributing founder was a sire with a 3.22% contribution, and the highest contributing founder dam made a contribution of 1.75%. The effective number of founders and the effective number of ancestors were 141 and 88, respectively. The study showed that genetic variation within the pedigree population has been decreasing over recent years. Increasing the number of AI bulls with a low individual coefficient of inbreeding could help to maintain a good level of genetic variation in the Brown Swiss population.

Sugarcane is an important forage source for dairy cows in tropical countries. However, it provides limited digestible fiber and energy intake, and fat supplementation can be a way to increase energy density and decrease dietary, non-fiber carbohydrates concentrations. We aimed to evaluate the performance, digestion and metabolism of dairy cows in early lactation fed different concentrations of soybean oil (SBO) in sugarcane-based diets. Fourteen primiparous (545±17.2 kg of BW) and eight multiparous (629±26.7 kg BW) Holstein dairy cows were used according to a randomized block design. After calving, diets were randomly assigned to cows within the two parity groups. Diets were formulated with increasing concentrations of SBO (g/kg dry matter (DM)): control (0), low (LSBO; 15.7), medium (MSBO; 44.3) and high (HSBO; 73.4). The study was performed from calving until 84 days in milk, divided into three periods of 28 days each. Dry matter intake (DMI) was affected quadratically in response to SBO addition with the greatest and lowest values of 19.0 and 16.0 kg/day for LSBO and HSBO diets, respectively. The digestibility of potentially digestible NDF was quadratically affected by SBO with the greatest value of 623 g/kg for LSBO diet. Both milk and energy-corrected milk (ECM) production were quadratically affected by SBO inclusion, with greatest ECM values of 27.9 and 27.3 for LSBO and MSBO, respectively. Soybean oil inclusion linearly decreased milk fat concentration by 13.2% from control to HSBO. The CLA t10,c12-18:2 was observed in milk fat only for MSBO and HSBO diets. Soybean oil inclusion did not affect plasma glucose or serum concentrations of total proteins, globulins, albumin, urea nitrogen, beta-hydroxybutyrate, non-esterified fatty acids or insulin. Serum concentrations of total cholesterol, triglycerides and low-density lipoprotein increased with SBO supplementation. Soybean oil inclusion in sugarcane-based diets for early lactation dairy cows from 15.7 to 44.3 g/kg DM can improve energy intake and performance; however, at 44.3 g/kg DM milk fat concentration and ECM decreased. Soybean oil inclusion at 73.4 g/kg DM adversely affected energy intake, fiber digestion and performance of early lactation dairy cows and is not recommended.

A total of 233 does were subjected to laparoscopy in order to study the relationships between litter size (LS) and its components, using linear and quadratic models. The relationships were essentially linear, but there was a quadratic relationship between ovulation rate (OR) and the number of live embryos at 12 days of gestation. OR explained a small proportion only, but prenatal survival a greater proportion of the variation in LS. Both embryo survival and foetal survival were of similar importance and appeared to operate independently.

Two trials involving young pigs (total numbers 288 and 400, respectively) were performed to compare the biological activity of Dl- and L-tryptophan under restricted (trial 1) and ad libitum (trial 2) feeding conditions. In trial 1, three additions of Dl-tryptophan (0·3, 0·6 and 0·9 g/kg) and two additions of L-tryptophan (0·3 and 0·6 g/kg) to a basal diet containing 0·9 g natural tryptophan per kg were tested. In trial 2, the treatments were additions of 0·4, 0·8 and 1·2 g Dl- or L-tryptophan per kg to a basal diet having 1·3 g natural tryptophan per kg. Both trials were of 6 weeks duration. In trial 1, almost equal performance was achieved with both tryptophan sources at a dietary level of 0·3 g/kg, whereas at a level of 0·6 g/kg, Dl-tryptophan produced slightly better performance in weight gain, food intake and food conversion efficiency than did L-tryptophan. In trial 2, the supplemental level of 0·4 g L-tryptophan per kg produced weight gain and food intake results which were significantly superior to those of Dl-tryptophan. However, at supplemental levels of 0·8 and 1·2 g/kg, diets with Dl-tryptophan produced somewhat better performance than did L-tryptophan. Based on the results of trial 2, it was estimated that the pig's need for total tryptophan over the weight range of 10 to 35 kg is at least 2·3 g/kg in a diet having 10·3 MJ net energy per kg.

Inbreeding has been associated with the impairment of reproductive performance in many cattle breeds. Although the usage of reproductive biotechnologies has been increasing in bovine populations, not much attention has been given to the impact of inbreeding over cow’s performance on artificial reproduction. The objective of this study was to estimate the impact of inbreeding on in vitro embryo production in a Guzerá breed population. The inbreeding coefficient (F), calculated as half of the co-ancestry of the individual’s parents, was used as an estimate of inbreeding. The inbreeding coefficients of the donor, sire (used on in vitro fertilization) and of the embryos were included, separately, in the proposed models either as classificatory or continuous variables (linear and quadratic effects). The percentage of non-inbred individuals (or embryos) and mean F of donors, embryos and sires were 29.38%; 35.76%; 42.86% and 1.98±2.68; 1.32±3.13; 2.08±2.79, respectively. Two different models were considered, one for oocyte production traits and other for embryo production traits. The increase of F of the donor significantly (P<0.05) impaired the number of viable oocytes (NOV), number of grade I oocytes (NGI) and number of cleaved embryos (NCLV). Moreover, the donor’s F influenced the percentage of grade I oocytes (PGI), percentage of viable embryos (PEMB) and percentage of cleaved embryos that turned into embryos (PCXE). No significant (P>0.05) effects were observed for the sire (father of the embryos) inbreeding coefficient over the traits analysed. Embryo’s F influenced (P<0.05) the number of viable embryos (NEMB), percentage of viable embryos (PEMB) and percentage of cleaved embryos that turn into embryos (PCXE). Results suggested that an increase in the inbreeding coefficient might impair the embryos ability to survive through challenges imposed by the in vitro environment. Submitting highly inbred Guzerá female donors to in vitro embryo production may, in the long-term, have negative implications on the number of embryos obtained per cow and increase the relative costs of the improvement programmes based on this technology. High levels of inbreeding should be avoided when selecting Guzerá female donors and planning in vitro fertilization mating.

The effects of continuing spatial restraint were examined in domestic pigs. For this purpose, the animals (German Landrace barrows) were housed individually in metabolic cages (12 animals) and, as controls, in single pens (six animals). In six replications with two experimental animals and one control animal, we collected saliva each morning (0730 h) for the cortisol analysis, recorded the behaviour and the heart beat for 3 h/day (0800 to 0900 h, 1100 to 1200 h, 1400 to 1500 h). Each replication consisted of 5 days of habituation to single housing and 8 experimental days during which the experimental animals lived continuously in the metabolic cages. Weight gain, cortisol, heart rate and heart rate variability were not significantly affected by experimental narrow confinement that only had a significant influence on the behaviours, locomotion and sitting. In conclusion, the experimental animals adapted very fast and did not show physiological indications of chronic stress. However, the absence of apparent stress does not exclude other, subtler, welfare impairments.

Both glucosinolates and S-methyl cysteine sulphoxide (SMCO) have been implicated in the suboptimal intakes observed among lambs consuming forage brassicas. However, the effects on animal performance of the compounds administered in isolation have been marginal (Barry et al, 1982) and the toxicity of the compounds may be enhanced by interactions between their physiological effects. In order to test this, an experiment was conducted in which rumen metabolites of both SMCO and the predominant kale glucosinolate, sinigrin, were administered in combination to sheep and effects on voluntary intake and blood chemistry were examined. SMCO is hydrolysed in the rumen to dimethyl disulphide by a bacterial enzyme while sinigrin undergoes hydrolysis in crushed plant tissue to allyl isothiocyanate and allyl cyanide under plant enzyme catalysis.

Heat transfer coefficients are used to calculate convective and radiant heat losses from pigs of 4, 20 and 60 kg body weight at 20 and 30 °C environmental temperatures for different wind speeds. Comparisons with heat losses estimated from whole-animal calorimetry suggest that calculations with heat transfer coefficients can lead to useful approximate estimates of heat loss from the pig.

Intact male lambs from Limousin and Charmoise breeds, or crossbreds from F1 (Romanov × Limousin) ewes sired by Berrichon rams, were early weaned, intensively fed, and slaughtered between 20 and 40 kg of empty body weight. The whole carcass was chemically analyzed, and the results expressed on a shorn, empty body-weight basis.

Some between breed differences in the weight of fat and gross energy content were found: fat contents ranged from 179 to 212g/kg at 30 kg of empty body weight. The corresponding range for energy was 10·8 to 11·8MJ/kg of empty body weight. Differences between protein and ash contents were limited, from 154 to 165g/kg empty body weight, and from 31 to 33g/kg empty body weight respectively.

At the same empty body weight Charmois lambs (a small sized breed) contained more fat, less water and less protein than the crossbreds. Values obtained on the Limousin lambs were intermediate.

There was no evidence of diet or growth rate effect on chemical composition when compared with published data obtained from more conventionally fed lambs.

Differences in the metabolic resource situation between non-reproductive male and female mice of a line selected for high litter size at birth (average of 22 born per litter) and a non-selected control line (average of 10 born per litter) were investigated in two replicates. Brody curves were fitted to individual data on body weight against age and linear regression lines were fitted to individual data on cumulative food intake against age. Mature body weight and mature daily food intake were higher in selected mice than in control mice and higher in males than in females. Selected males matured faster than selected females and control mice. In general, differences in growth and food intake curves between species or lines can mostly be explained by differences in mature size. Therefore, parameters were subsequently scaled by individual estimates of mature body weight. Differences that remain after scaling are a consequence of what have been called specific genetic factors. Scaled mature food intake was higher in selected mice than in control mice and higher in females than in males. Scaled maturation rate was higher in selected mice than in control mice and higher in selected males than in selected females. This shows that in the present study, specific genetic factors have been detected for both body weight and food intake, which suggests that selection for increased litter size has disproportionally changed the resource allocation pattern.

The protein-rich non-conventional detoxified karanja cake (dKC) can be used in place of conventional protein supplements like soybean meal (SBM), groundnut meal, etc. in livestock feed. The present study was conducted to assess the effect of two levels of dKC by replacing SBM on testicular architecture, semen quality and expressions of mRNAs encoding luteinizing hormone receptor (LHR) and insulin-like growth factor (IGF-I) in testes of ram lambs. Eighteen ram lambs were randomly divided into three groups (n = 6) and fed different levels (%) of karanja cake (0% replacement – control; 50% replacement – dKC-50 and 75% replacement – dKC-75) for 140 days. After 120 days of feeding, the semen from the animals was collected and analysed. The testes samples were collected on day 140 of feeding for transcripts expression studies. The dKC-50 group had no change in BW, whereas dKC-75 group showed decreased (P < 0.05) BW as compared with control. The number of animals ejaculated semen in dKC-75 group was lower (P < 0.05) than the control group. A reduction (P < 0.05) in LHR expression in dKC-75 was observed, whereas a reduction in IGF-I expression (P < 0.05) was observed in dKC-50 and dKC-75 as compared with control group. The study reveals that in ram lambs, long-term feeding of dKC at 50% replacement of SBM may not affect BW. However, long-term feeding of dKC as a replacement of SBM may affect testicular function.

Results are presented from six trials dealing with aspects of management on the cold ad libitum system of calf rearing using an acidified milk replacer containing over 600 g skim milk powder per kg.

Thirty-six calves were housed in pens of six for each trial and were fed through a teat and pipeline from a storage barrel. Acidified milk replacer, pH 5·6, was mixed cold at 125 g/1 and made available ad libitum to 3 weeks. A rationed allowance was given daily, on a reducing scale, over the following 2 weeks with weaning completed at 35 days. A pelleted dry food containing 180 g crude protein per kg, together with water in buckets and barley straw in racks, was available ad libitum throughout. Each trial lasted 8 weeks. Results for the mean of the six cold ad libitum trials involving 216 calves were compared with the mean results of 10 conventional bucket-fed trials carried out separately at the same unit, involving 912 calves. All calves were purchased British Friesian male (bull) calves.

Calves on the ad libitum system showed improved live-weight gains of 9·4 kg at 3 weeks, 8·8 kg at 5 weeks and 7·5 kg at 8 weeks, compared with the conventional system. The consumption of milk replacer powder was higher in ad libitum trials at 29·4 kg cf. 12·5 kg by bucket but intake of pelleted dry feed was lower on the ad libitum system at 50·7 kg cf. 71·3 kg to 8 weeks. Calf appearance scores were significantly improved on the ad libitum system which gave the main improvement in performance in the first 3 weeks.

Analyses of variance were conducted using two separate random sets of data (25 158 and 24 084 records) on first-lactation, milk-production records of progeny of 69 British Friesian-Holstein proven sires in order to examine the criteria of seasonal grouping for a sire-evaluation model fitting herd-year-season as a fixed effect. Five different seasonal groupings were chosen each comprising two or three seasons with equal or unequal number of months and with different trends in production within season.

The smallest herd-year × month of calving within-season interaction, smallest residual variance, largest effective number of daughters and smallest among-months, within-season variation were considered to be the appropriate criteria of seasonal grouping. None of the groupings examined satisfied all criteria. However, a small herd-year × month within season interaction and all small within-season variation would be desirable if milk records were pre-corrected for the effect of month of calving in sire evaluation, and the effective number of daughters should be large. Given this the grouping currently used in Britain (three seasons: December to March, April to July and August to November) was considered to be appropriate, although a grouping with two seasons: February to July and August to January gave similar results. The regional differences in production were observed to be large, but the region × month-of-calving interaction was small.