An automated method of estimating the spatial distribution of piglets within a pen was used to assess huddling behaviour under normal conditions and during a febrile response to vaccination. The automated method was compared with a manual assessment of clustering activity. Huddling behaviour was partly related to environmental conditions and clock time such that more huddling occurred during the night and at lower ambient air temperatures. There were no positive relationships between maximum pig temperatures and environmental conditions, suggesting that the narrow range of air temperatures in this study was not a significant factor for pig temperature. Spatial distribution affected radiated pig temperature measurements by IR thermography. Higher temperatures were recorded in groups of animals displaying huddling behaviour. Huddling behaviour was affected by febrile responses to vaccination with increased huddling occurring 3 to 8 h post-vaccination. The automated method of assessing spatial distribution from an IR image successfully identified periods of huddling associated with a febrile response, and to changing environmental temperatures. Infrared imaging could be used to quantify temperature and behaviour from the same images.

The reproductive performance of does of New Zealand White (N) and Californian (C) strains of rabbit was compared with that of the two reciprocal crosses, C × N and N × C (sire × dam). Both types of crossbred doe showed a reproductive performance superior to the purebred strains, having both a higher conception rate and mean litter size at birth. C × N, N × C, N and C does reared on average 6·6, 7·4, 5·0 and 4·9 pups to weaning age respectively. Expressed in terms of an estimated annual production of weanlings the N × C does produced nearly twice as many progeny to 4 weeks of age as the purebreds N and C (37 pups cf. 21 and 19 pups respectively). Total losses prior to weaning were approximately 25% in all breeds, largely from stillbirths, and subsequent chilling and/or starvation in the nest (36% and 38% of diagnosed deaths respectively). Other contributory factors are discussed.

The present value of future genetic improvement in a closed population is taken to be proportional to the sum of discounted changes in the population mean. It is shown that, if T animals are available for selection and R is the discount rate per generation, the selection intensity which maximizes present value is a function of TR. If TR is greater than 15, under 10% of the population should be selected. It is then shown how T can be chosen to maximize profit if the value of genetic improvement and cost of testing are known. The theory is illustrated by a numerical example.

The effect of reducing energy intake within the practical range or reducing energy intake without reducing protein intake on chemical composition of gain, whole-body protein turn-over and energy metabolism was studied between 33 and 90 kg live weight with seven replicates of five littermate boar Landrace pigs. Three levels of food intake (ad libitum, 0·90 and 0·80 ad libitum) were used and the dietary protein contents ranged from 250 to 312 g crude protein (CP) per kg dry matter (DM) to equalize protein intake with reduced food intake. All the diets were of similar amino acid composition and were offered twice daily as pellets. There was no effect of dietary treatment on the DM, CP and fat contents (g/kg) of the empty body (EB), but fat content and fat: protein ratio in EB tended to decrease with reduction of food intake or energy intake. The relationship between energy intake and protein deposition was linear and the mean maximum protein retention was 187 g/day. Retention of DM (P < 0·001), protein (P < 0·001), fat (P < 0·001), energy (P < 0·001) and ash (P < 0·01) decreased linearly with reducing food intake or energy intake. The calculated residual heat production was 0·604 MJ metabolizable energy per kg M0·75 per day. The dietary treatments had no effects on composition of longissimus dorsi, fillet, liver, kidney, backfat or kidney fat. The nitrogen flux, nitrogen synthesis and breakdown tended to decrease with reduction in food intake or energy intake though the effects were not statistically significant. Nitrogen accretion decreased significantly (P < 0·05).

An experiment conducted at two experimental stations was designed to identify the limiting amino acids in maize-soya-bean meal diets with 120 g crude protein per kg given ad libitum to pigs from 20 to 40 kg body weight. The effects of additions of tryptophan and of tryptophan plus threonine in both the presence and absence of added methionine were studied. The responses to supplemental amino acids were not significantly different at the two stations (P > 0·10). The addition of tryptophan tended to improve growth rate. However, significant improvements in rate and efficiency of gain were not realized until both tryptophan and threonine were added (P < 0·05). Interactive effects between supplemental amino acids on pig performance were not detected. Thus, the maize-soya-bean meal diet with 120 g crude protein per kg and given ad libitum to 20-kg pigs appeared to be limiting in lysine, tryptophan, threonine and possibly methionine.

This study was aimed at evaluating (1) the dry matter (DM) and nitrogen (N) degradabilities (by sheep) of Sesbania sesban leaves, Acacia albida (Faidhabia albida), A. siberiana and A. tortiris frazfs and (2) the effect of feeding a mixture of oilseed cake and tanniferous browses on the degradability of teff (Eragrostis tef) straw and oilseed cake and on particulate and liquid passage rates. Thirteen rumen cannulated sheep in a randomized complete-block design experiment were given teff straw ad libitum supplemented (DM per day) with 155 g oilseed cake (50: 50 mixture of noug (Guizotia abyssinica) and groundnut cake; oilseed cake diet) or with 92 g oilseed cake plus either 118 g S. sesban (sesbania diet) or 179 g A. albida fruits (albida diet). Diets were formulated to supply 10·5 g supplementary N per day.

Sesbania had the highest DM washing loss, potential degradability and fastest DM degradation rate compared with the acacias. The N washing loss (g/kg) was highest for A. siberiana (500) followed by A. albida (431), A. tortilis (431) and sesbania (241). The potential N degradability (g/kg) was greater (P < 0·05) for sesbania (978) than for A. albida (848), A. tortilis (865) or A. siberiana (785). The degradation rates of oilseed cake-N and teff straw-DM, particulate and liquid passage rates, basal intake and DM digestibilities were similar among diets, but organic matter intake was highest for the albida diet. At the present levels of offer, supplementation with mixtures of oilseed cake and browses does not significantly reduce rumen degradation rates of oilseed cake-N or teff straw DM.

A total of 7444 lactation records which include milk, fat and protein yields (MY, FY, PY) and fat and protein content (F%, P%) from 6429 Black-Faced Latxa ewes were employed to estimate genetic parameters for milk traits. Traits were standardized to 120 days of lactation. For the calculation of composition traits, not all test-days had their composition measured and therefore a correction taking this into account was included in the analysis. A first-derivative restricted maximum likelihood algorithm was used on an animal model with repeatability analysis, using models including fixed effects (flock-year-season of lambing, age-parity at lambing, number of lambs, interval between lambing and first milk recording and the combination of sampled test-days) and random effects (the additive genetic effect and the permanent environmental effect). The resulting heritabilities were 0·20, 0·16, 0·18, 0·14 and 0·38 for MY, FY, PY, F% and P% respectively. Heritability of F% was much lower than expected, probably due to problems derived from the recording method. Genetic correlations were high and positive between yields and moderately positive between F% and P%, and negative or null between yields and composition, as has been reported for other European dairy sheep breeds. As most of the milk produced by Latxa dairy sheep is processed into cheese, the inclusion of milk sampling in official milk recording and a change in the selection criterion are recommended to avoid a long-term worsening in milk composition.

A selection experiment with Scottish Blackface sheep was used to compare predicted and realized responses to selection. Three closed lines, of approximate annual size of 270 ewes and 10 rams, were maintained between 1956 and 1974, in which selection was at random, or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age. An unselected base flock (1954-55) and the randomly selected line were used to estimate base population parameters, while the selected lines were used to estimate realized responses to selection.

Heritabilities and genetic correlations were obtained in the unselected lines from a variety of collateral and ancestral relationships. The important components of phenotypic variance were estimated and likely responses to selection predicted for the index and its two component traits. Realized responses to selection were estimated from the regression of response on selection differential. The expected variance-covariance matrix of observed responses was included in generalized least-squares estimates of these regressions.

The realized heritability of the index under selection, estimated from the divergence of selected lines, was 0·52 (s.e. 0·02). After allowing for the expected reduction in heritability arising from linkage disequilibrium, this was very similar to the base population estimate of 0·56 (s.e. 0·04). The responses in the component traits of the index were also very close to those expected from base population parameters

The time spent under a shelter by eight grazing fattening bulls of the Belgian Blue breed in each of 3 years consecutively for a total of 48 days was recorded using a time-lapse recorder with infrared illumination.

During one grazing period, data were collected over 35 days (experiment 1). Observations were divided into 166 h with rain (20%) and 674 h without precipitation (80%). The average occupation rates were 15·4 (s.e. 29·1) % for the hours with rain and 4·5 (s.e. 14·8) % for the hours without precipitation (P < 0·001). The effect of intensity and duration of rain on the occupation rate was significant from 0·4 l/m2 or from 2 h.

Experiment 2 (13 days of observation) examined the influence of temperature and solar radiation on the use of shelter. The occupation rates were 21 (s.e. 23) % during the daylight hours (07.00 to 19.00 h), 6 (s.e. 8) % during the night (19.00 to 07.00 h) and 14 (s.e. 14) % during a 24-h period. The occupation rate between 07.00 and 19.00 h was significantly correlated to the mean daily temperature (r = 0·75), the maximum daily temperature (r — 0·86) and the direct solar radiation time (r 0·60). When the maximum daily temperature exceeded 20°C, the use of the shelter increased from 10 to 49% of the daylight hours.

There was no significant difference between the live-weight gains of animals from the observed group and those of other bulls on an adjacent pasture without shelter. Nevertheless, these observations suggest that a shelter may improve the welfare of grazing cattle.

Twenty-four castrate male cattle were used in two nutritional balance and slaughter experiments to measure the effects of two implantations with 300 mg trenbolone acetate and 36 mg resorcylic acid lactone over the live-weight range 250 to 400 kg. Control and implanted animals were pair-fed barley-based diets of differing protein concentration in the first experiment and the lower protein diet at two levels of feeding in the second experiment.

Daily live-weight gain and nitrogen retention were significantly increased by implantation in both experiments. The carcasses of implanted animals contained significantly more lean meat and a higher proportion of meat in the forequarter. The edible portion of these carcasses contained significantly more protein and water and less fat.

Live-weight gain and carcass composition were not influenced by dietary protein intake. Increased feeding level improved live-weight gain, suggesting that a higher metabolizable energy intake would give an increased response to implantation.

Suffolk and Rambouillet female sheep (ewes) were kept in pens where daylight was gradually reduced and were treated, or not treated, with hormones to obtain four lambing cycles in 2·5 years. Oestrus in May, June and July was induced more easily (P<0·01) in Rambouillet than the Suffolk ewes. The advantage of higher conception rates in the Rambouillet ewes during anoestrus was offset by the higher prolificacy rates in the Suffolk in the other three lambing cycles. On average, each breed produced 128 lambs per 100 ewes exposed per lambing cycle. This corresponds to 5·1 lambs per ewe in four lambings, which is equivalent to 2·04 lambs per ewe per year. Under the conditions of the experiment, the addition of Syncro-Mate pessaries (20 mg fluorogestone acetate) and pregnant mare serum gonadotrophin (PMSG, 5 ml/ewe, 50 IU/ml) to the treatment of reduced daylight did not affect the ovulation or conception rates.

Grazing and stall-feeding experiments were conducted to examine the effect of giving different amounts of cereal-protein concentrate with grass on the live-weight gain of cattle initially 6 months of age. The effect of level of concentrate on grass intake was also studied in the indoor trial. Experiment 1 took place at pasture, with two stocking rates (high and low) and three levels of supplementation at each stocking rate. The response to supplementation, and rate of live-weight gain by the unsupplemented groups was similar at both stocking rates for a 101-day period from late April to mid-August. The results are discussed in relation to other pasture supplementation experiments, and to those obtained in the indoor experiment. Experiment 2 (stall-feeding) consisted of five levels of concentrate feeding from zero to 100% of the diet. There was little increase in total intake as the proportion of concentrate in the diet increased, and the relationship between grass intake and concentrate intake was rectilinear.

Gut fill estimates are presented for each level of concentrate feeding, and results for empty body-weight gain are discussed in relation to live-weight gains. There was a linear increase in weight gain with increasing proportion of concentrate in the diet. Empty body-weight gain is recommended as a less biased assessment of the response of cattle to concentrates given with pasture or forages.

Fat depths of Southdown and Suffolk rams were ultrasonically measured several times prior to 18 months of age. Ultrasonic measurements were regressed on live weight and deviations from this regression were standardized and summed to select rams with high and low fat depth to produce crossbred progeny for slaughter. An average of 3·24 standard deviations separated high and low sires. Progeny were slaughtered at two ages to determine differences in carcass fatness and its development. A significant difference of 0·5 mm fat depth over the loin eye muscle was found between progeny of low and high sires. Progeny from Suffolk high sires had greater tissue depth over the rib and higher kidney fat weight than those from Suffolk low sires but differences were small or reversed in Southdown progeny. Low progeny had significantly less estimated carcass chemical fat than high progeny. Fat depth C increased less in low progeny between early and late slaughter ages. However, no difference in partition of carcass weight gain to fat weight gain was observed between high and low progeny. Differences in fat weight between high and low progeny, as well as between Southdown and Suffolk progeny, appeared to have occurred prior to the earlier slaughter age.

Contractile and metabolic properties of bovine muscles play an important role in meat sensorial quality, particularly tenderness. Earlier studies based on Myosin heavy chain isoforms analyses and measurements of glycolytic and oxidative enzyme activities have demonstrated that the third trimester of foetal life in bovine is characterized by contractile and metabolic differentiation. In order to complete this data and to obtain a precise view of this phase and its regulation, we performed a proteomic analysis of Semitendinosus muscle from Charolais foetuses analysed at three stages of the third trimester of gestation (180, 210 and 260 days). The results complete the knowledge of important changes in the profiles of proteins from metabolic and contractile pathways. They provide new insights about proteins such as Aldehyde dehydrogenase family, Enolase, Dihydrolipoyl dehydrogenase, Troponin T or Myosin light chains isoforms. These data have agronomical applications not only for the management of beef sensorial quality but also in medical context, as bovine myogenesis appears very similar to human one.

A study was undertaken to determine the magnitude of any financial loss incurred in the utilization of pale, soft exudative (PSE) pigmeat. Twenty pairs of first-grade bacon-weight carcasses were selected on the slaughter line. Members of each pair were of the same sex and weight but one had an m. longissimus dorsi pH at 45 min post mortem (pH1) of 5·4 to 5·8 (PSE) and the other a pH, of 6·2 to 6·5 (normal). One side of each carcass was processed for Wiltshire bacon and the other was cut into retail joints, which were packaged, placed in a refrigerated cabinet and measured for drip loss 72 h later. PSE, compared with normal carcasses, had a lower bacon yield (16g/kg) and drip loss from fresh PSE meat was more than double (17·0 v. 7·0g/kg trimmed carcass weight). In shop testing, the sales of bacon from the two types of carcass were similar; with the fresh meat fewer PSE cuts were sold (0·23) but mainly during the final test day. It would appear that an economic assessment of PSE meat in Wiltshire curing need consider a reduced bacon yield only (= £1·13 per carcass at the present difference of 0·8 kg). The reduced financial return on a PSE carcass of similar weight for fresh meat was calculated to be zero to £8·74, depending upon the type of retailing operation and effort devoted to ensuring an early sale of PSE cuts.

In order to study the effect of day length and temperature on performance, data from 495 growing, non-castrated bulls of the Swedish Red and White breed were analysed. Groups of 11 bulls were housed in either an insulated building in pens having slatted floors or in an uninsulated building with pens having both a deep straw bed and a concrete floor. The majority of the bulls (330) were given a concentrate diet ad libitum, while the remainder (165) were given grass silage ad libitum supplemented with concentrate. Energy intake, live-weight gain, housing temperature, day length and change in day length were calculated as 14-day period means for the two housing systems. Regression analyses showed that live-weight gain was associated with increasing day length in bulls on both feeding treatments. For bulls given concentrate ad libitum, metabolizable energy intake was associated with increasing day length. The intake of heavier animals was more influenced by day length than that of those which were lighter. The seasonal influence on daily energy intake in bulls given silage did not show the same pattern as for bulls given concentrate ad libitum. The intake was highest in June and lowest in December for the bulls given concentrate but for the bulls given silage it was highest in August, September and October and lowest in March and April. This was due to the varying quality of the grass silage over the year. No effect or very little effect of temperature or housing system on energy intake or on weight gain was found.

Thirty-six British Holstein-Friesian cows were offered 9 kg dry matter (DM) daily of one of 12 concentrates together with grass silage ad libitum in a cyclical change-over design experiment during lactation weeks 8 to 22. The carbohydrate source in the concentrates was either mainly starch, mainly digestible fibre or a 1:1 mixture. Each concentrate type was formulated to provide 120, 160, 200 or 240 g crude protein (CP) per kg DM and similar metabolizable energy concentration. Silage contained 142 g CP per kg DM, in vivo digestible organic matter was 0·690 kg/kg DM, pH 4·4 and ammonia-N 172·2 g/kg total nitrogen.

Silage intake increased as fibre replaced starch in the concentrate. Apparent digestibility of organic matter and energy were highest for starch-based concentrates, but there was no effect of carbohydrate source on yields of milk and milk solids. Milk protein concentration was depressed by feeding mixed or fibrous carbohydrates.

Silage intake increased on average by 0·13 kg DM per additional 10 g/kg CP in the concentrate. The digestibility of the diet was not affected by increasing CP except for nitrogen. Milk yield increased by 0·028 kg per additional g/kg CP in the concentrate and there were linear effects ofCP on yields of milk solids.

As CP increased, milk fat concentration tended to rise with starch but was depressed both overall and by offering mixed or fibrous carbohydrates. In contrast milk protein concentration increased with mixed and fibrous carbohydrates but not with starch.

It is concluded that when silage is given ad libitum with 9 kg/day concentrates, CP level has more effect than source of carbohydrate on milk production.

Oestrous activity, ovulation rates and embryo survival rates were investigated in Border Leicester × Scottish Blackface (Greyface) ewes with condition scores of approximately 2·75 (moderately fat) or 3·5 (very fat) at mating. Four of a group of 20 very fat ewes failed to show oestrus at the expected time. Very fat ewes had a higher mean ovulation rate (3·36 v. 2·33; P < 0·05) but a slightly lower potential lambing rate (1·10 v. 1·42 lambs born per ewe put to ram) than the moderately fatewes.

The model incorporates, amongst its novel components, variable efficiency coefficients in the simulation of the responses of growing pigs to nutrient inputs, and thereby increases the accuracy and efficacy of control of feeding and nitrate excretion. The model determines (rather than is presented with) net energy and required amino acid level and balance. The estimation of protein turn-over as a function of rate of protein retention, protein mass and the maturity of the pig was found to be central to both the energy (ATP) and protein economy. Protein turn-over varied from around 0·14 to 0·08 of the protein mass depending upon the size of the pig. Efficiencies of energy yield from lipid, starch (and sugar), protein and (fibre-derived) volatile fatty acids were calculated to be 0·98, 0·86, 0·56 and 0·58 for ATP production and 0·90, 0·70, 0·50, and 0·44 for lipid retention, respectively. The maximum efficiency of use of ileal digestible amino acids was determined as around 0·85. The energy cost of protein synthesis was equivalent to 4·2 MJ metabolizable energy (ME) per kg, and the efficiency of use of ME for protein retention varied from 0·55 to 0·40 depending on the protein mass of the pig. The components of the model and the biochemical drivers are described in detail, and proof of principle of the main elements is presented. The model is different in its architecture to other published simulation models, and is considered to add to the present knowledge base in this discipline.

The genetic and economic efficiency of alternative selection schemes and breeding objectives for the Karagouniki dairy sheep in Greece was investigated by model calculations. Criteria of efficiency were the annual genetic gain for the aggregate breeding value, the profit per ewe in the population and the annual selection responses for single traits. The introduction of a two-tier selection scheme, where the recorded ewes are separated into a nucleus and a pre-nucleus, was found superior in both genetic and economic terms for a breeding objective comprising the traits milk yield and number of lambs weaned per ewe per annum. Highest rates for annual genetic gain and selection responses were obtained when the nucleus size was proportionately 0·05 of the population (200 000 ewes), the size of the test matings 0·50 to 0·60 of the size of the pre-nucleus unit (0·10 of the population) and the number of daughters per test ram 40. Opening the nucleus to replacement ewes from the lower tier did not affect positively the annual genetic gain and the selection responses. Furthermore, a breeding objective comprising the traits fat yield and number of lambs weaned per ewe and per annum was found very efficient in both genetic and economic terms while selection on growth and carcass traits did not seem to be justified.