The aim of this work was to evaluate the effect of a short-term addition of an antibiotic food additive (50 mg zinc bacitracin per kg food) on skatole concentration in faeces, blood (vena jugularis) and backfat of boars kept under two housing conditions at summer temperatures. They were kept clean or were heavily fouled with faeces plus urine. The experimental material consisted of six litters in each of four replicates, in total 24 litters, each litter of four boars. Fourteen days before slaughter the boars were distributed to the four treatments in four equally large pens according to litter and start weight. Two pens had a wholly slatted floor and two pens had a concrete floor, and each pen held six boars allowing 0·6 m2 per boar. All boars were kept at high pig house temperatures (22°C). In the two wholly slatted-floor pens the boars were kept very clean and in the two concrete floor pens boars were kept heavily fouled with faeces and urine during the final 14 days before slaughter. Boars in half the pens of both floor types were given an antibiotic food additive (50 mg zinc bacitracin per kg food) in the last week before slaughter.

Administration of the food additive zinc bacitracin significantly decreased the skatole level in blood and backfat in both clean and dirty boars when used for 3 and 7 days before slaughter. The experiment further confirmed that boars at high stocking rate and lying in copious amounts of warm faeces and urine at temperatures of 25°C or more, for at least a week, had higher indole and skatole levels in blood and subcutaneous fat than pigs which were kept clean. The androstenone concentration in backfat was not significantly influenced by either of the two treatments. A highly significant correlation between skatole in blood (vena jugularis) and in backfat was found at the day of slaughter (r = 0·98).

One hundred and twenty spring-born steers, comprising 40 Friesians (FR), 40 Meuse-Rhine-lssel (MRI) × Friesians (MR), and 40 Belgian Blue × Friesians (BB) were reared together from 3 weeks of age to the start of their second winter. During the second winter there was a 3 (FR, MR and BB breed types) × 2 (3 kg and 6 kg supplementary concentrates per head daily with grass silage ad libitum) × 2 (96- and 220-day finishing periods) factorial arrangement of treatments (10 animals per subgroup). Carcass weights and grades were recorded after slaughter at the end of the second winter, and one side from each of 96 carcasses (eight per subgroup) was dissected into bone, muscle, intermuscular fat and subcutaneous fat. A sample of m. longissimus from the 10th rib was chemically analysed. Slaughter weights and carcass weights per day from arrival to slaughter were 796, 813 and 828 (s.e.d. 11·7) g and 419, 440 and 457 (s.e.d. 7·1) g for FR, MR and BB, respectively. Corresponding carcass weights were 314, 329 and 342 (s.e.d. 4·5) kg. BB had better conformation than both FR and MR. BB also had a lower carcass fat score, lower proportions of bone, intermuscular fat and subcutaneous fat, a higher proportion of muscle and muscle with higher proportion of moisture and a lower proportion of lipid than FR and MR. The higher level of concentrates increased side iveight by 8 kg, but the overall effects on carcass composition were small. The longer finishing period increased side weight by 25 kg and was associated with significantly reduced proportions of bone and muscle and an increased proportion of fat. Allometric regression coefficients for carcass weight on slaughter weight, and for bone, muscle and fat weights on side weight were 1·19, 0·39, 0·80 and 2·16, respectively. It is concluded that despite the better carcass conformation of MR, there was little difference in carcass and muscle composition between FR and MR. BB, in addition to having a higher growth rate and better carcass conformation than FR, also had more muscle in the carcass, more of the total muscle in the higher value joints and a lower proportion of lipid in the muscle. It was calculated that FR, MR and BB would have similar proportions of separable fat in the carcass at approximate carcass weights of 300, 320 and 400 kg, respectively.

During lactation 30 sows were given a basal diet containing 0·39% lysine or the same diet supplemented with 0·1, 0·2, 0·3 or 0·4% Llysine. In addition a group of six sows was given a high protein/high lysine control diet containing 17% crude protein and 1·06% lysine. Piglet weight gain, sow milk yield, milk contents of total solids, protein, fat and energy and efficiencies of utilization of energy and protein for milk production increased progressively as dietary lysine levels were raised to 0·59 %. Sows receiving the lysine-supplemented diets had markedly higher efficiencies of conversion of dietary protein into milk protein and lower efficiencies of energy utilization than those given the high protein/high lysine control diet.

Nitrogen retention and biological value of the dietary protein increased quadratically with increasing dietary lysine concentrations, reaching maximum values at 0·59% lysine.

Apparent digestibilities of isoleucine, lysine, methionine, threonine and valine in the basal diet were closely correlated with digestibility of nitrogen. Plasma lysine concentrations remained depressed and relatively constant at low dietary levels of lysine, but increased sharply at 0·59 % dietary lysine coinciding with a marked drop in circulating concentrations of other essential amino acids.

Sixty Angus steers (413 ± 8.0 kg) were used to determine the effects of copper (Cu), maize type, and finishing system (confinement v. pasture) on performance, carcass characteristics, and fatty acid composition of longissimus muscle in steers. Steers in confinement were given individually high concentrate diets containing either typical or high-oil maize, using Calan gate feeders. Steers grazing pasture (tall fescue) were maintained in four pastures with each pasture containing five steers. Salt was used to limit concentrate intake in pasture steers to approximately 0.6 of that observed in confinement steers. One half of the steers in each treatment received a CuO needle bolus at the initiation of the study while the remaining steers received no supplemental Cu. Equal numbers of steers per treatment were harvested after 91, 112 or 133 days on food. Rate of gain was lower (P < 0.01; 1.2 v. 1.6 kg/day) for pasture-fed steers compared with steers receiving typical maize. Cu supplementation increased (P < 0.05) ADG in steers given typical maize (1.8 v. 1.5 kg/day) and those on pasture (1.3 v. 1.1 kg/day) but not in steers given high-oil maize diets (1.5 v. 1.5 kg/day). Gain, dry-matter intake and gain/food did not differ between steers given typical or high-oil maize. Plasma cholesterol concentrations were lower (P < 0.01) in steers given typical maize relative to steers given high-oil maize. Steers receiving a Cu bolus had higher plasma (P < 0.05) and liver (P < 0.01) Cu concentrations than steers not receiving a Cu bolus. Steers receiving typical maize had lower (P < 0.05) liver Cu concentrations than steers receiving high-oil maize. Steers finished on pasture with limited concentrate had conjugated linoleic acid (CLA) concentrations in longissimus muscle that were approximately three times higher (P < 0.01) than steers given typical maize. Cu supplementation tended (P < 0.10) to increase muscle CLA. Longissimus muscle from pasture-fed steers was lower (P < 0.01) in C16: 0 and higher (P < 0.05) in C10: 0, C17: 0, C18: 3, C20: 3 and total polyunsaturated fatty acids than steers given typical maize. Muscle C18: 1 trans and C17: 0 tended to be reduced (P < 0.10) by Cu supplementation. These results indicate that finishing cattle on pasture with limited grain increases CLA in longissimus muscle and that Cu supplementation also alters the fatty acid composition of muscle.

The aim of this study was to investigate whether fatty acid (FA) profile, oxidative stability of lipids and other meat quality traits differed between high (HW: 1.8 to 2.2 kg) and low (LW: 0.8 to 1.2 kg) birth weight piglets. Forty new-born male pigs (n=20 HW, n=20 LW) were reared in separate pens until the finishing period, when they were slaughtered at 150 days of age, and pH and temperature were measured in the carcass. Afterwards, the Longissimus dorsi muscle was excised from the carcass, and samples were collected for subsequent meat quality analyses (thaw loss, cooking loss, shear force, chemical analysis and sensory analysis for tenderness). Birth weight had minor impacts on meat quality traits, which were limited to higher shear force in the LW group (P<0.01). Chemical components (moisture, protein, fat, ash), cholesterol levels and lipid oxidation (thiobarbituric acid-reactive substances) were not affected by birth weight (P>0.05). FA profile and the amount of saturated, monounsaturated and polyunsaturated fatty acids were similar, but HW pigs had higher atherogenic index than their LW counterparts (P<0.01). Notwithstanding the higher shear force presented by the lower birth weight pigs, in the sensory test, the panelists did not detect any differences in the tenderness of pork from HW and LW animals. Therefore, our results suggest that low birth weight has minimal impact on meat quality.

Birth weight was recorded in the first and second litters of six inbred strains of mice and of all possible crosses between them. The mean birth weight of F1 young was significantly greater than that of inbred young in most cases; in no case were they significantly lighter than inbred young at birth.

Foetal weight and placental weight were recorded on the 17th day post coitum in the first litters of four strains and of two pairs of reciprocal crosses. F1 foetuses were 13–16% heavier than inbred foetuses on crossing four strains. F1 placentae were about 15% heavier than inbred placentae on crossing three strains. Crossbreeding did not affect placental weight in the fourth strain. The significance of these findings is discussed.

Analyses of data from individual strains and crosses showed that foetal weight was affected by the number of implants in the same uterine horn and independently by the number in the whole litter. The two independent effects, local and systemic respectively, tended to decrease foetal weight as litter size increased. The independent local effect of litter size on placental weight was different and tended to increase placental weight slightly as the number of implants in the same uterine horn increased.

Three different instances of maternal effects on foetal and placental growth were observed.

The effects of the litter and the mother on foetal growth are discussed in relation to the physiological basis of environmental variation in pre-natal growth.

Computer simulation was used to measure the effects of breeding management efficiency in block calving dairy herds and in those with a long mating season of 9 months. In particular, the effects of varying levels of oestrus detection and conception rates were assessed, and the product of these two parameters defined as the fertility factor. As the fertility factor increases from 20 to 50, where the mating season extends to 9 months, the mean calving index for the herd decreased linearly from 393·5 to 373·6 days and the culling rate for failure to conceive declines in curvilinear fashion from 0·196 to 0·006. Concurrent with the decrease in calving index, mean annual milk yield and margin over purchased food increase, with the herd commencing calving in January showing a more marked response than the herd commencing calving in October. When overall replacement rate is also taken into account, the margin over purchased food net of herd depreciation per cow, at 1979/80 prices, changes from £270·7 to £315·2 in the January herd compared with £275·9 to £315·8 in the October herd. For each day change in calving index associated with alteration in fertility factor, there is a change of £2·24 for the January herd and £2·01 for the October herd in margin over purchased food net of herd depreciation.

In the block calving herd, increases in fertility factor are reflected mainly in changes in culling rate for failure to conceive from 0·292 to 0·033, and not in margin over purchased food.

In this study, the first postpartum heat, termed the foal heat, characteristics and performance in female donkey (jenny) of Martina Franca are described. To this end, the follicular development of 42 jennies during foal heat was compared with that of 31 jennies at the third estrus after foaling. Estrus length (7.1±0.9 and 6.8±0.7 days), follicular development and preovulatory follicle size (43.7±3.5 and 45.1±2.5 mm) were similar between jennies during the foal heat and during the third estrus after foaling. The pregnancy rate at day 14 was significantly lower in the foal heat jennies (57.1%) than the third estrus jennies (82.3%). However, the pregnancy rate at day 14 in foal heat jennies increased significantly when the onset of foal heat was ⩾8 days after foaling (93.8%) or when the ovulation happened ⩾12 days after foaling (85.7%). The data provided in the present study suggest that the foal heat in the endangered jennies of Martina Franca could be successfully utilized to reduce the interpartum period if the onset of foal heat occurs >8 days after foaling.

A dynamic model for simulation of growth in pigs, extended to describe thermoregulatory processes, was made stochastic to simulate groups of pigs with between-animal variation in mature body protein (Pα) and lipid mass (Lα), in the potential rate at which mature mass is attained (B⋆), and in the distribution of body protein and lipid over pools and depots. The resulting variation in body composition leads to variation in energy requirements for protein turn-over and thermoregulation, causing between-animal variation in maintenance requirements (MEmaint).

Simulated population means for Pα, Lα /Pα and B⋆ were varied in three steps each. Excluding unrealistic parameter combinations this led to 33 – 6 = 21 simulated genotypes. Simulated within-population coefficients of variation (CV) were 7, 15 and 3%. Random replicates of each genotype were simulated five times, in climatic conditions that were in turn severely cold, mildly cold (about 5 and 1ºC below lower critical temperature), thermoneutral, mildly hot and severely hot (about 1 and 5ºC above upper critical temperature), during the entire growth period of 23 to 100 kg live weight. Simulated food intake was ad libitum.

Simulated thermoneutral within-population standard deviations of body protein and lipid content were 0·21 to 0·46 kg and 0·78 to 2·14 kg at 100 kg body weight. On average, the corresponding values in cold and hot conditions were slightly higher.

MEmaint showed a protein-turn-over-related within-population CV of 1·5% at thermoneutrality. Thermoregulatory action contributed about 4% extra variance in cold and hot conditions but CV values were not affected. A genetic increase in the maximum protein deposition rate from 100 to 250 g/day would increase MEmaint as related to protein turn-over and thermoregulation by 11% at thermoneutrality, and by 6 to 11% in cold or hot conditions. Two relevant groups of genotypes could be distinguished based on the within-population regression coefficients of MEmaint on daily or cumulative protein deposition (bdailyPdep, bcumPdep). These ranged from 0·250 to 0·428 kJ/kg0·75 per day per g/day and from 2·77 to 5·45 kJ/kg0·75 per day per kg, respectively, in 12 ‘conventional’ genotypes at thermoneutrality. On average, bdailyPdep was increased by 48%, 20%, –11% and –36% in the other climatic conditions mentioned above, respectively. The corresponding increase of bcumPdep was 32%, 14%, 8% and 48%. Three fast-growing lean genotypes showed similar bdailyPdep and bcumPdep at thermoneutrality, but much more pronounced increases in cold and hot conditions: 137%, 49%, –12% and + 88% for bdailyPdep and 248%, 108%, 17% and 196% for bcumPdep.

It is concluded that differences in body composition traits between pig genotypes do not cause important between-genotype differences in thermoregulatory MEmaint, and that thermoregulatory processes contribute little body-composition-related variation to hot or cold MEmaint within most genotypes.

The inferences to be made from this with regard to experimental design are discussed. The verification of the above predictions will require a very elaborate and large-scale experiment.

An experiment was conducted using 176 sows at three centres to investigate the effect of post-weaning feed level on reproductive performance. At two centres sows weaned 35 to 56 days after farrowing received 1·8, 2·3, 3·6 or 4·5 kg food/day from the day following weaning until the day following the last mating at the post-weaning oestrus.

At the third centre sows were rationed to 1·8, 2·3 or 3·6 kg food/day or given all they would consume in a single 1-hr feeding period each day. Reproductive performance of the sows was not significantly affected by post-weaning feed level.

We studied the effect of including genomic data for cows in the reference population of single-step evaluations. Deregressed individual cow genetic evaluations (DRP) from milk production evaluations of Nordic Red Dairy cattle were used to estimate the single-step breeding values. Validation reliability and bias of the evaluations were calculated with four data sets including different amount of DRP record information from genotyped cows in the reference population. The gain in reliability was from 2% to 4% units for the production traits, depending on the used DRP data and the amount of genomic data. Moreover, inclusion of genotyped bull dams and their genotyped daughters seemed to create some bias in the single-step evaluation. Still, genotyping cows and their inclusion in the reference population is advantageous and should be encouraged.

Crossbred wethers (34 (s.e. 0·9) kg), with catheters in a hepatic vein, the portal vein and a mesenteric vein and artery, were offered ad libitum alfalfa (A), bermudagrass (B) or ryegrass-wheat (RW) hay and approximately 0, 200 or 400 g/kg maize (dry matter) to determine influences of maize level on net flux of oxygen and nutrients across the portal-drained viscera (PDV) and liver with different forage sources. Digestible energy intake (MJ/day) was 8·5, 12·0 and 12·8 (s.e. VIS) for A; 4·5, 5·5 and 9·0 (s.e. 0·93) for B; and 9·4, 8·8 and 12·2 (s.e. 0·93) for RW with 0, 200 and 400 g/kg maize, respectively. Splanchnic bed oxygen consumption (mmol/h) was 301, 304 and 322 (s.e. 27·2) for A; 178, 187 and 217 (s.e. 30·0) for B; and 226, 133 and 233 (s.e. 19·0) for RW with 0, 200 and 400 g/kg maize, respectively. Increasing dietary maize level linearly increased (P < 0·05) PDV release of alpha-amino nitrogen with B (5, 9 and 14 mmol/h) but not with A or RW. Dietary maize level did not consistently alter PDV or hepatic net flux of urea or ammonia nitrogen, suggesting that changes in ruminally fermentable organic matter from diets offered ad libitum, presumably induced by varying dietary concentrate level, may not alter nitrogen recycling when forage is 86 g/kg or greater in crude protein. Propionate release by the PDV and hepatic uptake increased linearly (P < 0·08) as maize level in A and B diets increased, although increasing dietary maize level did not significantly alter PDV, hepatic or splanchnic bed net flux of glucose regardless of forage source. Nevertheless, glucose concentration in arterial blood with A and RW increased linearly fP < 0·05) with increasing maize level, suggesting increased peripheral glucose availability. In conclusion, the potential to decrease energy consumption by splanchnic tissues relative to digestible energy intake by dietary inclusion of maize, thereby increasing the proportion of absorbed energy available to extra-splanchnic tissues, may be greater for low-quality forage than for forage of moderate or high quality and for moderate v. low dietary levels of maize with low-quality forage.

There is community concern about the treatment of farm animals post-farm gate, particularly animal transport and slaughter. Relationships between lamb behavioural and physiological variables on farm, stockperson, dog and lamb behavioural variables pre-slaughter and plasma cortisol, glucose and lactate in lambs post-slaughter were studied in 400 lambs. The lambs were observed in three behavioural tests, novel arena, flight distance to a human and temperament tests, before transport for slaughter. Closed-circuit television video footage was used to record stockperson, dog and lamb behaviour immediately before slaughter. Blood samples for cortisol, glucose and lactate analyses were collected on farm following the three behavioural tests and immediately post-slaughter. The regression models that best predicted plasma cortisol, glucose and lactate concentrations post-slaughter included a mixture of stockperson and dog behavioural variables as well as lamb variables both on-farm and pre-slaughter. These regression models accounted for 33%, 34% and 44% of the variance in plasma cortisol, glucose and lactate concentrations post-slaughter, respectively. Some of the stockperson and dog behaviours pre-slaughter that were predictive of the stress and metabolic variables post-slaughter included the duration of negative stockperson behaviours such as fast locomotion and lifting/pulling lambs, and the duration of dog behaviours such as lunging and barking at the lamb, while some of the predictive lamb behaviour variables included the durations of jumping and fleeing. Some of the physiological and behavioural responses to the behavioural tests on farm were also predictive of the stress and metabolic variables post-slaughter. These relationships support the well-demonstrated effect of handling on fear and stress responses in livestock, and although not direct evidence of causal relationships, highlight the potential benefits of training stockpeople to reduce fear and stress in sheep at abattoirs.

As part of an investigation of factors responsible for a previously reported lower efficiency of carcass lean gain in steers offered grass silage diets, 16 Simmental × Friesian steers (515 (s.e. 6·4) kg) were offered perennial ryegrass silage ad libitum (C0) or silage plus rolled barley at 200 (C20), 400 (C40) or 600 (C60) g/kg total diet dry matter (DM). Barley-supplemented diets were intake-restricted to provide equal DM and metabolizable energy (ME) intakes to those offered C0. Eight steers were selected at random to determine the ME contents of the diets by open-circuit respiration calorimetry. The other eight steers were offered the same diets and were blood-sampled at 20- to 60-min intervals, for 10 h, to monitor changes in the concentrations of a number of nutritionally related plasma metabolites and hormones. Estimated ME intakes in these steers were 85·7, 83·1, 84·4 and 86·2 (s.e. 0·91) MJ/day from diets C0, C20, C40 and C60 respectively. Rumen-fistulated Hereford × Friesian steers provided 24-h rumen data for the same diets offered at equal amounts of ME per kg metabolic live weight.

Mean 24-h plasma concentrations of insulin and insulin-like growth factor 1 (IGF-1) were linearly and positively related (P < 0·01 and P < 0·001 respectively) and glucagon quadratically related (P < 0·05) to the proportion of barley in the diet. Plasma insulin increased after feeding on all diets but concentrations on diets C40 and C60 were significantly higher than those on C0 and C20 at all post-feeding sampling times up to 9 h after feeding. Plasma IGF-1 concentrations increased above pre-feeding levels following feeding of the higher barley diets (C40 and C60; P = 0·053) but remained unchanged in steers offered C0 and C20. Mean plasma concentrations of glucose were unaffected by diet but those of β-hydroxybutyrate (BOHB) and urea were positively and negatively related respectively (both P < 0·001) to the proportion of barley in the diet. Plasma BOHB and urea concentrations also changed with time after feeding (P < 0·001). Amongst the rumen parameters measured (pH; ammonia and volatile fatty acid concentrations and proportions) only the mean 24-h concentrations and proportions of butyrate were positively related to the proportion of barley in the diet (P = 0·051 and P < 0·05 respectively). All rumen parameters were affected by time after feeding (acetate, P < 0·01; others, P < 0·001) but there was no interaction between treatment and time for any parameter.

Twenty-one of 23 Finn and 23 of 28 Finn-Merino crossbred springborn males mated at about 6 mo of age during their first breeding season, whereas all of nine Merino males did not do so until the second breeding season at about 18 mo of age. The diameter of the testes of Finn and crossbred males at 6 mo of age was a higher proportion of their diameter at 18 mo than was that of the Merinos. Seasonal studies showed an earlier increase in the testis diameter of Merino males than that of the Finns or crossbred. At all seasons, the intensity of mating behaviour of Merinos was lower than that of the other breed types.

The results support the hypothesis that the reproductive activity of males is correlated with that of related females, and the use of male reproductive activity as a criterion for genetic selection for that of the female is discussed.

Days open data from 113 569 lactation records in 774 Spanish Holstein herds were analysed using standard linear models under two different editing procedures, and with two alternative methodologies that account for censoring: a censored linear model (CLM) and a Weibull survival analysis (SA) model. The first editing procedure excluded from the linear model all censored records for days open (LMnc), and the second defined days open as days from calving to the last known insemination or culling date, treating censored records as complete (LM). Sire variance estimates for days open were 61, 70 and 139 for LMnc, LM and CLM, respectively, and 0·026 for SA on a logarithmic scale. Heritability estimates were 0·05, 0·06 and 0·08 with LMnc, LM and CLM, respectively. Rankings of sires varied between methodologies: sire evaluations from LMnc and LM had rank correlations with evaluations from SA equal to −0·65 and −0·82, respectively, and of 0·71 and 0·87 with evaluations from CLM. The rank correlation between evaluations from SA and CLM was −0·98, suggesting stronger agreement of sire rankings between models that take censoring into account.The SA model had a better predictive ability of daughter fertility at early stages of lactation than the other methods, as measured by chi-squared statistics for predicted pregnancy status at 75, 103, 140, or 200 days post partum in a split data set. The CLM also predicted daughter fertility more accurately than any of the two standard linear models.

The factorial approach to assess the amino acid (AA) requirements of pigs is based on the assumption that the AA composition of body protein is constant. However, there are indications that this assumption may not be valid because the AA composition of body protein can be affected by the AA supply. The extent to which different tissues are affected by an AA deficiency is unknown. The objective of this study was to investigate the effect of feeding pig diets with a deficient or sufficient total sulfur AA supply (TSAA; Met+Cys) from 6 to 23 weeks of age on tissue composition and meat quality. The deficient diet (TSAA–) provided 24% Met : Lys and 51% TSAA : Lys on a standardized ileal digestible basis, which are 19% and 16% below the recommended requirements, respectively. The sufficient diet (TSAA+) provided 33% Met : Lys and 60% TSAA : Lys. Diets were offered slightly below the ad libitum feed intake capacity of the pigs. Pigs offered diet TSAA– had a lower average daily gain, lower weights of the longissimus dorsi (LM) and rhomboideus muscles (RM), and of selected skin sections (P<0.05). The weight of different sections of the small intestine and the liver was not affected by the diet. The protein content of the LM and RM decreased in pigs offered diet TSAA– (P<0.05), whereas the protein content of other tissues was not affected. The TSAA supply affected the AA composition (g/16 g N) of protein in all tissues, but the Met content was changed only in the liver (P<0.05). Pigs receiving diet TSAA– had a lower Cys content in the RM and in the distal jejunum and ileum (P<0.01). The deficient TSAA supply resulted in a lower carcass weight and higher muscle glycogen stores (P<0.05), but did not affect other meat quality traits. The results of this study indicate that the muscles, jejunum and ileum respond more to a prolonged AA deficiency than the liver. In addition, the observed changes in AA composition of tissue protein question the use of a constant AA profile of retained protein to assess AA requirements.

The influence of genetic and environmental factors on body weight and reproduction and their relationship to milk production traits, were studied in data of about 4700 Sahiwal cows from Pakistan. (Co)variance components were estimated using restricted maximum likelihood (REML) procedure based on the expectation maximization algorithm applying an animal model. Mean weights of females were: at birth, 21·6 kg; at 1 year, 130 kg; and at 2 years, 222 kg. Records of age at calving, cow weight post partum and calving interval were studied in the first three parities, with parities considered as different traits. For primiparous cows the average values of these traits were: 44·1 months, 319 kg and 465 days, respectively. Mean stillbirth rate was 5·3%. Heritabilities ranged for body weight traits from 0·08 to 0·21, for age at calving from 0·10 to 0·13 and for calving interval from 0·03 to 0·07. Genetic correlations of age at first calving with calving interval and 305-day milk yield were low. The genetic correlation between 305-day milk yield and calving interval was positive (unfavourable) in first parity (0·68) but negative in the third (-0·47). Cows with a high genetic value for 305-day milk yield were heavier at first calving than were low-yielding cows (rg 0·57). The genetic change in reproductive traits over the period studied was close to zero, whereas a marked deterioration was found in phenotypic performance. It is concluded that improved feeding and management, along with some selection against poor reproduction in cows, are important for improvement of reproductive performance.

The spread of anthelmintic resistance in equine strongyle nematodes has become a major problem, advocating for the development of alternative control for strongyles. Our study consisted of both in vivo and in vitro experiments. We investigate for the first time the efficacy of a short-term consumption of tannin-rich sainfoin (Onobrychis viciifolia) or extra proteins in naturally infected horses. We used 30 horses allocated into three groups of 10 individuals that received for 18 days either (i) a tannin-rich diet with 70% DM sainfoin pellets (Sd), (ii) a protein-rich diet with 52% DM Italian rye-grass pellets and 18% DM grinded linseed expeller (Pd), or (iii) a control diet with 45% DM barley and 25% DM cereal-based pellets (Cd). The three diets were isoenergetic, covering 94% of animal energy requirements on average, and the Sd and Pd diets were isoproteic and provided extra proteins (227% of protein requirements v. 93% for the Cd diet). Pd and Cd were compared to test for benefits of receiving extra proteins, while Sd and Pd were compared to account for the effect of sainfoin secondary metabolites. There were no between-diet differences in faecal egg counts (FEC) or in worm burden evaluated from worm counts in faeces of drenched horses at the end of the experiment. However, coprocultures from the faeces collected in each group at the beginning and at the end of the experiment suggested a lower rate of strongyle larval development in the Sd group at the end of the experiment (Sd=8.1%, Pd=30.5%, Cd=22.6%). In vitro tests using sainfoin solutions evidenced the influence of sainfoin on strongyle larval development: adding 29% of sainfoin pellets to faeces reduced the strongyle egg development into infective larvae by 82% (P<0.001) and using solutions with sainfoin concentrations higher than 7.5 mg/ml reduced egg hatching by 37% (P<0.05). The short-term use of tannin-rich plants in horse diet could thus constitute a promising strategy to reduce the risk of infection by strongyles at pasture.

An experimental design aiming at analysing the consequences of genetic selection from 1977 to 1998–2000 on the evolution of stress-responsive systems in the French Large White (LW) and Landrace (LR) pig populations was conducted by INRA and IFIP-Institut du Porc. Large White sows were inseminated with semen from LW boars born in 1977 (frozen semen) or in 1998 and their second-generation offspring were station-tested. Landrace sows were inseminated with semen from LR boars born in 1977 (frozen semen) or in 1999 to 2000, and their progeny was station-tested. Urinary concentration of stress hormones (cortisol and catecholamines) and traits related to carcass composition (estimated carcass lean content (ECLC) and global adiposity) and meat quality (pH 24 h) were measured. For the two populations, selection carried out since 1977 led to an increase in ECLC and a decrease in carcass adiposity. Between 1977 and 1998 to 2000, urinary concentrations of stress hormones were unchanged in the LR breed, but were decreased in the LW breed. Moreover, for the animals generated from LW boars born in 1977 and in 1998, urinary cortisol levels were negatively correlated with ECLC. Therefore, in the LW breed, selection carried out for higher ECLC resulted in a decrease in cortisol production, as well as a reduction of catecholamine production that may be responsible for the lower ultimate pH of meat. Therefore, selection carried out for increased carcass lean content led, in this breed, to large modifications in the functioning of the stress-responsive systems, thereby influencing a large range of physiological regulations and technical properties such as carcass composition and meat pH, which remained however in the normal range for acceptable meat quality.