Curing data were obtained from the carcasses of 54 boars (B), 58 gilts (G) and 46 castrates (C) reared from birth to slaughter at 89 kg live weight. Middle bacon rashers were compared for colour and incidence of fat splitting. The uptake of curing salts was similar for each sex group but carcasses of B retained proportionately 0012 less of the cure compared with G and C which did not differ significantly. Bacon yields from B, G and C at a final live weight of 88·6 kg were 40·6, 42·4 and 42·2 kg respectively. Sex did not influence the degree of splitting of the backfat layers in bacon rashers and had little effect on the colour of their lean tissue, but B compared with G and C tended to have a higher incidence of separation of the inner fat layer from the m. longissimus in the bacon rasher.

Probiotics (microbial preparations and their growth media) are of increasing interest as feed additives for both ruminant and non-ruminant livestock. Amaferm is a fermentation extract prepared from cultures of the fungus Aspergillus oryzae which, when included in the diet of dairy cows, increases the yield of milk and buttermilk (Harris et al. , 1983). These improvements have been associated with changes in rumen fermentation (Weidmeier et al., 1987). The present study describes the use of the rumen simulation technique Rusitec (Czerkawski and Breckenridge, 1977) to investigate the effects of increasing doses of Amaferm on the stoichiometry of rumen fermentation in vitro.

Amaferm was added at 0, 25 and 250 mg/d to duplicate Rusitec vessels and at 1 g/d to a single vessel, receiving 10 g/d of a mixed diet of hay, barley, molasses, fishmeal and vitamins/minerals (500, 299-5, 100, 91 and 9.5 g/kg DM respectively). Vessels were initially inoculated from animals receiving the same diet. Artificial saliva was continuously infused into the vessels (total volume 850 ml, dilution rate 0.88/d) and feed bags were changed daily such that each bag was incubated for 48 h. Samples were taken at the time of feeding after 15 d adaptation to Amaferm.

Amaferm had no influence on total VFA concentrations but there was a shift towards an increased proportion of butyrate as the level of addition increased. Ammonia production was also stimulated by the addition of Amaferm, with the concentration in the vessel receiving 1 g/d being almost twice that found in the control vessels. There was no effect on dry matter disappearance after 48 h. The concentration of methane in the gas collected from the head space of the vessels was decreased by Amaferm, with the maximum decrease (17%) being seen at the level of 250 mg/d.

Hormonal growth promoters (growth hormone (GH), β-adrenergic agonists, steroids) which improve growth rate and/or lean: fat ratios in the carcass have received considerable adverse publicity and are either banned or have no licence for their use in countries of the European Community. This has led to the development of a number of techniques, involving the use of antibodies, aimed at regulating metabolic processes involved in determining growth and body composition.

A number of these approaches have focused upon the GH axis, for example immunoneutralization of somatostatin (which normally inhibits GH secretion) to improve growth, the use of antibodies to GH which can enhance its effects in vivo and the development of antibodies which mimic the actions of GH. Although immunization against somatostatin has led to increased growth rates in a number of studies other studies have failed to demonstrate such an effect. A precise understanding of the mechanism of action of this approach is required before we can begin to understand why success is not assured. Antibodies which enhance GH action clearly do work reproducibly but the major problem in developing this approach is to produce an inexpensive peptide immunogen (its sequence derived from GH) which can be used to actively immunize animals so that their own antibodies enhance endogenous GH activity. Anti-idiotypic mimics of GH have also been produced which have GH actions in vivo but again this approach is of limited value until appropriate vaccines can be developed.

A different approach to the problem of excess fat deposition involves the use of antibodies directed against the plasma membranes of adipocytes in order to elicit their destruction and thereby limit the storage capacity for fat. This technique has been demonstrated in rats, sheep and pigs in both passive and active immunization techniques. Once again, however, this promising approach is limited by the lack of a commercially suitable vaccine. The identification of individual membrane proteins which are antigenic has been achieved and this provides the prospect of producing recombinant DNA-derived vaccines.

Whether these new approaches will be perceived as acceptable to the general public remains a serious concern and a potential limitation to their development as many would-be sponsors cut back their support for research in these areas.

Social learning can be of critical importance to cattle grazing rangeland environments with high variability of food resources across space and time. Experienced individuals can greatly facilitate foraging decisions (what to eat and where to eat) of naïve peers in such settings. We conducted an experiment with cattle to investigate strength and persistence of socially induced food and feeding site avoidance behaviours. Sixteen naïve yearling steers were paired with 16 social models that had either not been trained (control) or been trained with an emetic (LiCl), electrical shock or both to avoid: (a) an unsafe high-quality food (LiCl); (b) an unsafe high-quality feeding site (shock); or (c) both the unsafe high-quality food and the unsafe high-quality feeding site (LiCl + shock). Ten-minute trials were conducted in an experimental arena containing three artificial feeding sites each consisting of groups of bowls with either high- (HQ) or moderate-quality (MQ) foods (HQ = barley and oat grain; MQ = Bermuda grass hay). Unsafe high-quality (UHQ, surrounded by traffic cones) and safe moderate-quality (SMQ) feeding sites consisted of nine rubber bowls containing either HQ or MQ foods. The safe high-quality (SHQ) feeding site consisted of two groups of eight bowls containing HQ food, which surrounded the UHQ and SMQ feeding sites. Social models did not induce diet and feeding site avoidance behaviours in naïve steers; they exerted small and transient changes in the feeding behaviour of their naïve counterparts. Consequences to the individual outweighed social influences; when naïve animals experienced the same punishment contingencies as their social models, their behavioural patterns closely resembled those of their social model. Conditioned food and location aversions via LiCl were apparently influenced by prior exposure to target foods and the experimental arena. Conversely, conditioned feeding site avoidance via shock was apparently not influenced by prior exposure to target foods or the experimental arena.

A Number of authors (Bonsma and Neser, 1951; Bisschop, 1954; Wiener and Donald, 1955) have recently provided experimental evidence on the age at which the eruption of permanent incisors occurs in cattle and, in view of the wide ranges generally encountered, criticised the practice of estimating age from dental development. Though factors such as individuality, breed, plane of nutrition and type of grazing are frequently quoted as being responsible for deviations from the ‘accepted’ means (Miller and Robertson, 1952; Zorn, 1953), apparently little support is to be found in the scientific literature on the subject.

Forty-five Bos indicus (zebu) cows were blocked by body condition (BC) score at calving and allocated by body weight (BW) to three treatments: untreated controls (CON), and progesterone-releasing intra-vaginal device (PRID)-treated at either 45 (T45) or 60 days (T60) post partum. Cows were given food individually and blood-sampled three times a week for progesterone. Calves sucked twice a day and were weighed weekly. PRIDs resulted in only 21% of cows responding at 60 days and they did not reduce anoestrus (PPI) or calving interval (CI) (P > 0·05). Dry matter (DM) and metabolizable energy (ME) intake were 7·1 (s.e. 0·6) kg and 54·3 (s.e. 4·6) MJ/day, respectively. BC score and BW at calving, and ME intake influenced cow and calf average daily gain ranging from −580 to 625 and 331 to 868 g/day, respectively. Milk yield during the first 4 months was 507 (s.e. 97) l. Cows gained 25 kg per unit increase in condition but lost 50 kg for a unit decline. CI (mean 14·2, range 10 to 24 months) was inversely related to BC score at calving (r = −0·31) and was delayed by a long PPI (r = 0·51), ranging from 38 to 297 days. Most (95%) cows experienced one or more ‘silent ovulations’ before first oestrus, the number extending PPI length (r = 0·49, P < 0·001). Efficiency of ME utilization was higher for smaller cows of 240 (s.e. 28) kg at calving. It is concluded that: (1) PRID treatment before 60 days post partum is unlikely to reduce anoestrus in Boran zebu cattle; (2) given adequate energy intake zebu cattle in thin condition at calving initially replenish body reserves at the cost of lactation and experience more ‘silent’ ovarian activity before returning to oestrus; (3) cows in good condition at calving express maximum lactation potential, mobilizing their own body reserves to support milk production, yet resume oestrous activity earlier despite weight losses to support higher milk yields.

When barley has been used as a supplement to straw in diets for finishing cattle the performance achieved has often been below target. A trial was made to measure whether substitution of sugar beet pulp, a fibrous source of energy, for barley in such diets would Improve performance. Forty-eight Frieslan-type steers weighing 370 kg were offered long, Spring barley straw (variety Doublet) ad libitum. The straw was either untreated or treated with ammonia. Ammonia treatment was carried out in an oven with 3% anhydrous ammonia for 21 hours. Supplementation of the straw was designed to give a daily live weight gain of 1 kg. Animals offered untreated straw received 5.5 kg per head daily of dry matter (DM) from supplementary concentrates whilst those offered ammonia-treated straw received 4.5 kg concentrate DM. Included in the concentrates was 0.23 kg DM from white-fish meal and 0.07 kg of a mineral/vitamin supplement. The animals offered untreated straw also received 0.09 kg per head daily of urea. The remainder of the concentrates consisted of either bruised barley, a mixture of equal parts of DM from bruised barley and dried molassed sugar beet pulp, or sugar beet pulp only.

Fifty-six Landrace ♂ x Yorkshire ♀ gilts were divided at 140 days of age into four groups in a 2 x 2 factorial design whereby they were exposed continually (BE) or not exposed (NE) to a mature boar and were or were not blood sampled twice weekly for progesterone determinations.

There was no effect of BE on the age at the first or second ovulation. Since detection of oestrus was only 70·80% accurate, BE apparently delayed the onset of first and second oestrus by 16 days (p = 0·06). Blood sampling advanced first oestrus by 15 days (F = 0·07) and second oestrus by 32 days (P = 0·001).

The results suggest that gilts are unlikely to be responsive to boar exposure at 140 days of age, that observations of oestrus alone may be a misleading end-point of the effect of boar exposure and that the use of blood sampling for the measurement of progesterone as an index of ovarian activity may attenuate the response to stimuli intended to advance puberty in the gilt.

Trials have previously shown that during the first 48 hours of life, new born piglets are reluctant to use forward-creep areas. In the neo-natal period, in order to prevent piglets lying in the danger-zone, luxury creep heating has been proposed. This comprises temporary heating at the rear and sides of the sow. On commercial farms, various luxury creep-heating systems are used. In an attempt to increase the precision and safety aspects of luxury creep-heating, a purpose-built device has been developed on a commercial farm. Trials were therefore undertaken, in co-operation with Eastern Electricity, to compare this system to a conventional forward-creep system.

A total of 124 litters supplied only with a 150 watt heater in the creep box (Control) was compared to 124 litters provided with the luxury regime. The supply line for the luxury device is shown diagramatically in Figure 1. It comprised a timber-mounted mains electricity power-line, temporarily suspended prior to farrowing above and behind groups of 4 sows. The line provided three 13 amp sockets for each litter and supplied a 300 watt dull-emitter located behind the sow and two 175 watt, dull emitters suspended in the side creep areas.

Previous studies in foetal and growing sheep have shown that prolonged administration of β-agonist drugs leads to selective but marked attenuation of cardiovascular, metabolic and endocrine responses to the natural catecholamine hormones adrenaline and noradrenaline, as well as attenuation of responses to the drug itself. The experiment reported here was carried out to determine whether administration of the β-agonist drug, salbutamol, by twice-daily intramuscular injection at rates of 40 or 200 μ/kg per day, for a period long enough to result in substantial attenuation of its metabolic and endocrine effects, might also result in impairment in the ability of treated animals to respond to stressful husbandry procedures which disturb metabolic homeostasis and which depend on increased sympathetic nervous and adrenal activity for the restoration of homeostasis. Serial blood sampling on day 1 and day 14 of salbutamol treatment showed that the large increases in plasma lactate and glucose observed on the 1st day were absent on day 14, while the rapid increases in free fatty acids and insulin observed on day 1 were very greatly attenuated. Daily blood sampling also demonstrated that salbutamol, like cimaterol, significantly decreased both pre- and post-feeding plasma insulin and glucose concentrations.

Metabolic and endocrine changes consequent on herding and immersion of the lambs in a sheep-dip, were unaltered by 14 days of salbutamol treatment, even though the procedure resulted in activation of the pituitary-adrenal axis as evidenced by increased β-endorphin and cortisol concentrations, and a large increase in plasma lactate concentration. These results suggest β-agonist-treated animals can respond normally to physiological stresses but further investigations remain necessary to determine whether responses dependent on increased lipid mobilization and shivering, such as shearing or prolonged exposure to severe cold, remain normal in β-agonist treated animals.

The contribution of matrix metalloproteinases (MMP) to timely discharge of the placenta from bovine uterus at parturition is yet inconclusive, partly because of the presence of multiple MMP forms in situ. In the current study, the expression of different gelatinase subtypes on non-retaining placentas of Holstein cows was fingerprinted by using gelatin zymography. Different topographic regions on the placenta were measured separately, including the placentome-like structure and the fetal and maternal sides of interplacentomal placenta, all sampled from the central and peripheral areas of the placenta, respectively. The spontaneously ruptured umbilical cords were cross-sectioned as fetus end, middle and placenta end also for separate measurement. Body fluids including blood samples from the parturient cows, their neonatal calves and umbilical cord, as well as fetal fluids and the first colostrum were measured concomitantly. Results showed multiple forms of gelatinases subtypes in the placenta tissues and body fluids, including neutrophil gelatinase-associated lipocalin (NGAL)-MMP-9 complex, both the latent and active forms of MMP-2 and MMP-9; of them, the latent forms were much more abundantly and frequently expressed than the active forms. NGAL-MMP-9 complex was more prevalently present in the body fluids than in the placenta tissues. No distinguishable pattern of the expression of any gelatinase subtype was observed among the placentome-like structure, interplacentomal placenta and umbilical cord, or between fetal and maternal sides. Nonetheless, for interplacentomal placenta, proMMP-9 expression was higher in the central than in the peripheral area. In addition, proMMP-2 expression was higher in the rupture end (fetus end) than the placenta end of the umbilical cord. In conclusion, the current validated gelatin zymography detected a gradient proMMP-9 expression on the non-retaining placenta of cows in reverse to the proximity to the umbilical insertion point, and a gradient proMMP-2 expression on a section of the umbilical cord in reverse to the proximity to the rupture site, suggesting roles played by gelatinases in normal discharge of the placenta at term.

A method for the iterative set-up of optimum designs for crossbreeding experiments was used to study the robustness of designs to differences in the biological interpretation of two-locus epistatic interaction. Designs could be found which are efficient for the estimation of genetic models including, alternatively, seven different types of epistatic effects. Also, the design efficiency of a large-scale beef cattle crossbreeding experiment between Angus and Hereford cattle conducted at the Clay Center, Nebraska, and reported by Koch, Dickerson, Cundiff and Gregory (1985) was investigated and found to be high (proportionately 0·88 of the optimum). It was concluded that choice of the right genetic groups (i.e. types of crossbreds) seems to be more important for a good design than the exact number of observations allocated to each group.

Over 95% of laying fowls in the UK are now housed in conventional battery cages. In recent years the general public and more specifically an Agricultural Committee on Animal Welfare in Poultry (1981) have raised doubts concerning the welfare of hens maintained this way and have called for further studies on alternative systems.

Consequently investigations into three alternatives to battery cages have been initiated: a range and covered strawyard system at The West of Scotland Agricultural College and a modified deep litter system at The East of Scotland College of Agriculture. The main objective of these investigations is to determine the practical feasibility and welfare consequences of the respective systems as alternatives to cages for keeping laying fowls. As well as recording productivity, the behavioural activities and distribution of wing-tagged birds have been monitored within the flocks of both the strawyard and deep litter systems. In all three studies ISA Brown layers were used and compared with sister stock housed in cages.

The variations that occur in saliva flow in cattle at rest may affect digestive processes in the reticulo-rumen (Bailey and Balch, 1961). To learn more about the effects of variations in saliva flow on digestion, it would be of value to have a reliable method of measuring saliva flow in intact animals. Stevens and Sellers (1959) showed that emptying the rumens of cows altered the rate at which saliva was swallowed and suggested that this was a result of changes in the rate of secretion. The rate of swallowing was measured during the course of experiments on saliva secretion described earlier (Bailey and Balch, 1961). Those earlier values are here analysed to study the relationship between rate of secretion of saliva and rate of swallowing.

The morphological development of the sheep and the goat is different and this difference is manifested from early post-natal life. The main characteristic of kid goat carcasses is their low adipose tissue, and this is considered detrimental to quality. In an attempt to determine the nutritional causes of this, a study was performed with kid goats of the Granadina breed and lambs of the Segureña breed. Six kid goats and six lambs were slaughtered at birth, while a further eight kids and eight lambs were fed a milk replacer to satiety until the 60th day of life and slaughtered on the 61st day. Dry matter (DM) and metabolizable energy (ME) intakes and apparent digestibility of energy were determined in four balance periods between 8 and 60 days of life. From the intakes of ME and comparative slaughter data it was possible to calculate energy retention (ER), heat loss (HL) and energy retained as protein (ERp) and as fat (ERf) for kids and lambs. Kid goats showed a similar apparent digestibility of energy to lambs but had lower DM and ME intakes per kg metabolic body weight (M0·75) than lambs. For kids and lambs respectively these values were: 0·93 and 0·94; 45·4 and 50·1 g/kg M0·75 per day; 937 and 1033 kJ/kg M0·75 per day. Mean values for ER, HL, ERp and ERf rates were: 263, 674, 131 and 132 kJ/kg M0·75 per day for kid goats and, 343, 690, 132 and 211 kJ/kg M0·75 per day for lambs. Together with the different intake, kid goats showed a lower rate of ER and overall, a lower rate of ERf than lambs.

Intensively reared rabbits are particularly sensitive to heat stress. For this reason it is useful to identify reliable stress indicators to evaluate peculiar stress conditions of the breeding environment.

In order to recognize which changes in biochemical and functional measurements can be utilized as stress indicators, three groups of eight New Zealand White rabbits, of 2·8 kg body weight and 11 weeks of age, were kept in individual cages and submitted to different environmental conditions.

Group 1 was located in a climatic chamber at 33·5 (s.e. 0·5)°C and relative humidity 0·62 (s.d. 0·05) and groups 2 and 3 (control) at 18·0 (s.d. 0·5)°C. Group 1 was given ad libitum a commercially pelleted diet, group 2 was pairfed with group 1, and group 3 was given food ad libitum. For all the groups, at days 0, 1, 6, 12 and 24, the following measurements were made: body weight, rectal temperature, food consumption and plasma glucose, cholesterol, urea, triglycerides, uric acid, and glutamate oxalacetate transaminase, glutamate pyruvate transaminase, thiobarbituric acid-reactive substances, vitamin A and vitamin E, SH-groups and total (peroxil) radical-trapping antioxidant parameter (TRAP).

Food consumption of animals exposed to 33·5 °C was strongly reduced in the 1st day (13·6 v. 161·6 glday); a gradual increase until the end of the trial was then observed (98·8 v. 177·3 gl day). Rectal temperature rapidly increased and remained stable and higher than in the control groups all through the trial (P < 0·01). The major changes in the measurements of the heat stressed animals were a significant increase of the plasma level of vitamin E at days 6, 12, 24 (P < 0·05), and a significant reduction of the plasma concentration of SH-groups and TRAP (P < 0·05).

The results suggest an impairment or overload of antioxidant systems after thermal stress, indicating a reduced resistance to biological and environmental stress factors. The results also indicate that some parameters of antioxidant systems can be used to select a significant stress indicator.

Six lines of mice were fed distinctive fixed or shifting diets while being selected for fast growth in the first two weeks after weaning. The intention was to provide alternative routes for the improvement of growth with respect to a maize diet (100% maize) where controls grew 6 g, an optimum diet (76% maize, 24% milk) where controls grew 17 g, and a ‘milk’ diet (16% maize, 84% milk) where controls grew 12 g. After 10 generations of selection the lines, hybrids and unselected controls were compared on these and intermediate diets. Realized genetic correlations between growth on optimal and suboptimal diets depended on the feeding regime in which selection was practised, and were significantly higher in lines that were selected on suboptimal diets. When the selected lines were tested on unfamiliar suboptimal diets they were hardly better than controls, but on their own diets and also on the optimum diet were about 6 g heavier. Peak growth was never much greater than on 76% maize and was made on diets containing between 58% and 82% maize. With one exception, the hybrids grew on each test diet about as well as did the best selected line.

A genetic limitation was encountered on the optimum diet. The growth there of the mice selected on either milk or maize diets was not improved upon by the mice actually selected on the optimum diet.

The position of the incisor teeth in relation to the maxillary pad was examined in bulls (at approximately 10 months old). Visual gradings grouped into five classes were made on 5582 bulls of eight breeds in the course of inspection for licensing. In addition, measurements of the tooth positions (grouped into 11 classes) were made on separate samples of 1163 Galloway and 191 Ayrshire bulls.

Among the beef breeds 84·0% of all tooth positions were classed as being normal and 96·6% of those among the dairy breeds. The proportion of mouths with incisor teeth forward of the maxillary pad was higher among the beef breeds. Individual breeds within the beef and dairy types also differed significantly.

Herds of the Galloway and of the Ayrshire breeds, judged on the bulls submitted for licensing, differed in the distributions of the position at which the incisor teeth met the pad. Herds also differed when judged on the occlusion of the sons of their bulls.

Heritability was calculated for Galloways by half-sib correlation and sire-son regression, yielding estimates from 0·31 to 1·28, suggesting that at least some of the variation is inherited. The undershot and overshot conditions were found together only rarely among the male offspring of any one bull.

The importance of feeding the ewe well during pregnancy and lactation has long been realized, but differences of opinion exist as to what stage food, in addition to natural grazing, should be given. If, for example, a farmer had a limited supply of supplementary food, when would it be best to feed it? The answer to this question is dependent on factors such as breed of sheep, the expected lambing percentage, the grazing available and the weather conditions.

The female progeny of Angus, Boran and Red Poll bulls mated to Ankole, Boran and Zebu cows were compared. Heifers by Angus and Red Poll sires out of Boran and Zebu cows could be mated at an average age of 23 months with excellent calving percentages, whereas Boran-sired heifers and heifers from Ankole cows were not ready for service at this age. Lactation stress caused heifers suckling calves to lose 4% of body weight over a 7½ month suckling period, while heifers not suckling calves gained 14% in body weight. Heifers by Red Poll sires did not provide more milk for their calves, as measured by early growth rate, than heifers by Angus or Boran sires. The effect of hybrid vigour on mothering ability of F1 dams was at least as great as it was on the early growth of the F1 crossbreds themselves.