The use of laparoscopic intrauterine insemination to deposit semen directly into the tip of the uterine horn thus bypassing the involuting uterus ensures fertilization in ewes induced to ovulate at 3 to 5 weeks post-partum. Acceptable pregnancy rates are achieved if embryos from post-partum donors are transferred to a normal uterine environment (60%; Wallace, Robinson & Aitken, 1989a) but embryos rarely survive when transferred or returned to a post-partum uterus (0-25%; Wallace, Robinson & Aitken, 1989b; McKelvey, Wallace, Robinson & Aitken, 1989). Furthermore, when conceptus development was assessed at Day 16 after insemination only a small sub-set of post-partum ewes remained pregnant, suggesting that any defect in the maternal/embryonic dialogue which may inhibit the re-establishment of pregnancy in post-partum ewes occurs prior to this stage (Wallace, Ashworth, Aitken & Cheyne, 1991).

In the current study a novel blastocyst transfer procedure was developed to test whether the post-partum uterus can support conceptus development during the period of rapid growth coincident with the maternal recognition of pregnancy.

Inhibin is a dimeric protein hormone composed of two dissimilar, disulphide-linked subunits (termed α and β) involved in the negative feedback regulation of gonadotrophin secretion, preferentially FSH. Interfering with this negative feedback by active immunization against inhibin has resulted in a consistent increase in ovulation rate and litter size in sheep. However, similar results have not been achieved in cattle. This paper describes the effect of active immunization of heifers against either of 3 synthetic peptide sequences from the bovine inhibin α-subunit on inhibin antibody titres, ovulation rate, calving rate and twin-calving rate.

Three peptide sequences from the bovine inhibin a-subunit were identified as likely immunological epitopes by computer analysis. These peptides (P1: bl-α-[YG] (18-30); P2: bl-α-(63-72)[GY]; P3: bl-α-[CG](107-122) were synthesized by solid phase methods and tyrosyl or cystenyl residues, linked through a glycine spacer where appropriate, were added during synthesis in order to facilitate iodination and conjugation respectively.

The relative importance of genetic variation in ovulation rate and in embryo survival together with the genetic relationship between these traits are important issues in terms of manipulating prolificacy in all multitocous mammalian species. Evidence in sheep, primarily from study of breed differences but also based on results of selection for litter size, shows that genetic variation in litter size is essentially attributable to differences in ovulation rate although genetic differences in embryo survival have been identified. Results from selection on litter size also suggest that genetic variation in ovulation rate is independent of any variation in embryo survival. The evaluation of the relationship between these traits in sheep is somewhat problematical in most populations due to the low level of ovulation and particularly the associated high proportion of ewes which shed a single ovum. The objective of the present study was to use lines of Finn Sheep, a breed with a high ovulation rate and in which single ovulations are rare, which have been developed by divergent selection on ovulation rate to evaluate the genetic association between ovulation rate and embryo survival.

Progesterone or progestogens can be administered either intravaginally or via ear implants. The ear implant Synchromate B (SMB) has been used widely in the USA and Europe. SMB (Ceva laboratories) utilises a 6mg norgestomet ear implant with an intramuscular injection of 5mg oestradiol valerate and 3mg norgestomet. Crestar (Intervet, UK) is a similar regime but the ear implant contains 3mg norgestomet. The objective of this experiment was to evaluate the effectiveness of Crestar as a synchronising agent for potential recipients in an embryo transfer programme.

A total of 334 Hereford x British Friesian maiden heifers, housed in straw bedded pens were allocated at random to be synchronised using either a PRID (Sanofi) plus prostaglandin; or a Crestar (Intervet, UK) regime. Equal numbers of heifers received each treatment.

Early embryo mortality results in significant inefficiency in cattle breeding. A pregnancy rate of 65-70% to a single service, AI or transfer of fresh embryos is considered to be very good indeed. A pregnancy rate of 55-60% using frozen embryos would also be considered very good. Of the 30%, or so, of cattle which do not become pregnant to a single service, approximately one quarter are accounted for by fertilisation failure (Diskin and Sreenan, 1980; Roche et al, 1981) and another quarter by cytogenetic abnormalities in the embryos, which usually occur within the first few days after fertilisation (Hare et al. 1980; Gayerie de Abreu et al, 1984). Failure in the communication between embryo and uterus probably accounts for the remaining 50% of pregnancy loss. Fertilisation failure and early deaths due to cytogenetic abnormalities are by-passed by embryo transfer (ET) so that other causes of loss become rather more significant.

Efficiency has replaced productivity as the prime rationale for research and development in agriculture. The reasons for this are to (1) reduce input costs when output is static; (2) to make best use of limited renewable resources; (3) to conserve both non-renewable resources and the quality of the environment. Efficient agriculture and conservation are often seen as opposing arguments because parties are arguing from different, incomplete premises. Blaxter (1975) explored the biological efficiency of agricultural systems using energy as a unit of account. He recognised that it was primarily the use of fossil energy as fuel (0.42) and as fertiliser (0.38) that had increased the productivity of U.K. agriculture but that “in the long term …the world must eventually reach a steady state in which energy provision will not entail a depletion of its capital resources.“

Much has been written about the changing structure of dairy farming in Europe in the last decade, but comparatively little has been said about the processing sector. Yet the future market for milk largely depends on the success of the dairy trade in adapting to the new market environment. Accordingly, this paper concentrates on the pressures and strategic issues facing the milk processing sector in Europe. Certainly, in recent years it has had to cope with radical changes in both the production and consumption of dairy products. After several decades of uncontrolled expansion in milk production, the introduction of milk quotas by the European Community in 1984 was a rude shock. In general, the industry was still geared to an expanding milk market. Almost overnight, it was faced with the problem of excess processing capacity.

Stereotypies such as bar-biting and sham-chewing, inactivity and unresponsiveness are behavioural responses to confinement in pigs. A link between stereotypies and opioids in sows, has been established by Cronin et al.,(1986) who found that the opioid antagonist naloxone inhibited some stereotypies. Stereotypies exhibited different degrees of resistance to the disruption by naloxone, in Cronin's experiment. Modulation of opioid receptors can be influenced by chronic treatment with opioid agonists and antagonists (Blanchard, and Chang,1988). Similarly, opioid receptors can be up or down-regulated by stressful stimuli such as restraint, electric footshock or social isolation (Zeman et al., 1988). In the study reported here mu, delta and kappa receptor densities and affinity were measured post-mortem. A comparison was made between sows which had been tethered or group-housed on commercial farms. The receptor densities were also compared with the behaviour which tethered sows had shown during the latter stages of pregnancy, as well as with their reproductive peformance.

A considerable amount is now known about the endocrine and neuro-endocrine control of parturition. Far less is understood however about the effect of events which may be considered stressful on the parturition process, despite its broad relevance to animal welfare and farm animal production. There is evidence that stress can have highly disruptive effects during parturition. For example, it has been suggested, that in pigs the behaviourally restricting farrowing crates used in commercial farming practice give rise to increased inter-piglet birth intervals and piglet mortality (Vestergaard and Hansen, 1984). Recent work on rodents has suggested that inhibtion of oxytocin secretion mediated by endogenous opioids, might be responsible for prolonged parturition following an acute stress such as a mid-partum change of environment. The aim of the present work was to extend the study of the effects of stress at parturition to a large animal model. We report two studies on the effects on parturition and oxytocin secretion of movement in mid-parturition to a novel environment (environmental disturbance). In Experiment 1 the effect of this disturbance on inter-piglet interval was investigated. In Experiment 2 a fuller investigation was made of the effects of environmental disturbance on a range of measures including inter-birth interval, behaviour of the sow and plasma oxytocin and Cortisol levels. The role of opioids was investigated in both experiments by administration of the opioid antagonist naloxone.

Previous work (Terlouw et al., 1991) has shown that confined sows only developed stereotypies when kept under food restriction. Furthermore, highest levels of stereotypies were found immediately after feeding. The present study tested the hypothesis that stereotypies in food restricted sows are specifically stimulated by food ingestion.

Experiment 1. The experiment was conducted on 13 restrained and food restricted sows (parity: 2; Cotswold Pig Development Co. Ltd, UK), receiving 2.5 kg of a concentrated sow food (13 MJ/kg) at 0900 hrs and that had shown post-meal stereotypic chain manipulation (range 0-300 min/day) and excessive drinking (range 6-50 litres/day) for 7 months. Two treatments were given in the afternoon, when they were generally inactive; 1) novel sound (duration 10 min) 2) unexpected extra meal (approximate ingestion time 10 min). Each treatment was repeated twice, with two treatment days per week. Days preceding treatment days were used as controls. Chain manipulation and drinking were recorded continuously using an automatic logging system.

Recent years have seen a small but consistent growth in the use of AI on commercial pig farms in Britain. Currently about 12 percent of all matings are artificial and 25 percent or more of farms are using some AI.(6) This figure still falls well short of our continental neighbours, with Denmark and the Netherlands inseminating 50 percent of their sows. The conception rate and litter size achievable with AI (6) can at least equal results from natural matings. However, it is recognised that some people achieve far superior fertility results to others when using AI. Part of this is due to different genotypes employed (e.g. purebreds vs crossbreds), different production systems and management practices imposed. It is most likely, however, that an unquantified but substantial part of the reason for such big differences between farms in fertility following AI is due to differing abilities of stockpeople performing the inseminations. “Ability’ refers not only to the actual insemination technique, which is straightforward and can be quickly learned, but to their general ability to recognise behavioural changes in their stock, to interact with their stock and generally get the best out of their stock i.e. their level of stockmanship skills.

Pigs from 4 farms were slaughtered at 2 abattoirs, each with 2 slaughter handling systems. Pigs at abattoir 1 were electrically stunned, either in a floor pen holding 5 pigs or a race restrainer. A straight race 1m wide led to the floor pen. A stepped collection pen and single file race led to the race restrainer. At abattoir 2 a single file curved race led to a floor pen with electrical stunning and a circular collection pen led to a double race and dip-lift C02 stunner. Each replicate involved 2 farms sending 50 pigs to each abattoir. There were 16 replicates (3200 pigs). Stun system had a significant effect on the development of early rigor, muscle pH, muscle colour and skin blemish (GLM Analysis of Variance). At abattoir 1, pigs slaughtered through the race restrainer had a greater tendency to develop early rigor and more skin blemish. Pigs slaughtered through the race restrainer also had lower pH in the m. longissimus dorsi at both initial and ultimate readings post mortem. In general, pH readings were higher than would be expected in the pig m. longissimus dorsi. Muscle reflectance was higher in the m. longissimus dorsi of pigs slaughtered through the race restrainer at both initial and ultimate readings. Significant differences between means at abattoir 1 (two-sample t-tests) are contained in Table 1. At abattoir 2, the floor pen produced carcases with a greater tendency to develop early rigor and more skin blemish. There were no significant differences in muscle pH or colour. Significant differences between means at abattoir 2 (two-sample t-tests) are contained in Table 2.

Results from the Langhill Dairy Cattle Research Centre (a joint venture between the Scottish Agricultural College and the University of Edinburgh) have confirmed that cows with a high genetic index for fat plus protein are more efficient (ME in milk divided by ME in feed) and more profitable (margin over food costs) than low index cows (Simm et al 1991a). Although food is one of the major costs of production it is important to monitor the consequences of selecting solely for fat plus protein yield on other costs, such as health and reproduction as well. This paper includes further results from a project supported by the Hoistein Friesian Society of Great Britain and Ireland. The aim of the study reported here is to examine the contribution which pedigree index, liveweight and linear type traits make to the prediction of margin over food, health and reproduction costs of individual cows.

The total amount of feed eaten by ruminant animals in a given period of time depends on the number of meals eaten in that time, the duration of each meal and the rate of eating during each meal (Bines, 1976). It has been suggested that differences in the pattern of intake with differing silages may influence the rate of nutrient release within the rumen, and thereby alter the efficiency of use of ingested nutrients (Gill et al, 1988).

An experiment was carried out to examine the eating behaviour of 48 lactating dairy cows offered 5 silages with contrasting fermentation characteristics, with silages produced using a range of silage additive treatments.

The treatments consisted of five silages harvested between 2-6 July from a perennial ryegrass based sward which had previously been harvested between 18-19 May. Herbage was ensiled either untreated (C), treated with an inoculant (I), inoculant with enzymes (I + E), formic acid (FA) or high levels of mixed aliphatic carboxylic acids (A). Animals were allocated to a randomized block design with 9 animals/treatment on treatments I, I+E, FA and CA and 12 animals on treatment C. Eating behaviour was monitored using a system in which cows were identified from collar borne transponders as they ate from weighed blocks of silage (Forbes et al, 1987).

In an attempt to increase the value of distillery by-products, in the 1970's many Scottish distilleries installed drying plants and dried distillers wet grains and pot-ale syrup together to produce dark grains. The feeding value of these dark grains for ruminant livestock has been well researched in America and researchers Firkins et al (1984) concluded that the protein component of dark grains is partially resistant to degradation in the rumen and this protein fraction can be more efficiently utilised by some classes of ruminant livestock than rumen degradable protein.

The current trial considered replacement or partial replacement of proprietary concentrate with one of three types of dark grains. The dark grains were from cereal sources - either barley, wheat or maize.

Twenty-one British Friesian cows in early lactation were used in an incomplete changeover design experiment consisting of four periods each of four weeks duration.

The sodium (Na) requirement of dairy cows is dependent on the level of production and the physiological state of the animal (ARC, 1980). In a previous paper (Chiy and Phillips, 1991), it was shown that changes in pasture growth rate and composition following sodium (Na) fertilizer application in mid-season to a dairy cow perennial ryegrass pasture leads to increased grazing and ruminating times, milk yield and milk fat concentration. Adding Na to concentrate also increased ruminating time and milk fat concentration. The effects of different levels of Na fertilizer have not been reported. The aim of the present experiment was to compare the effects of 0 (Nil), 32 (Low) and 64 (High) Kg Na /ha/year appied as fertilizer, with ( + ) or without (-) a sodium bicarbonate (NaHC03) buffer added to a concentrate supplement on cow production and ingestive behaviour during the grazing season.

Fifty four cows in their second or later lactation, and with a mean calving date of 4 February 1990, were allocated to sextets. Within sextets, cows were allocated to one of six treatments in a split-split-plot design arranged in a 24 X 3 X 2 factorial: weeks 1 to 24 of experiment; 0 (Nil), 32 (Low) or 64 (High) Kg Na ha/year and with (+) or without (-) 100 g NaHC03 included in 2 Kg maize gluten supplement/ cow/day.

It is not clear when the optimum time of harvesting the winter barley as whole crop for silage should be in terms of feeding value for dairy cows and yield of the crop. Little information is available using whole crop barley as a buffer feed. The aim of these experiments was to evaluate the feeding value of whole crop barley (WCB) silage harvested at three stages of growth as a supplementary feed for grazing dairy cows during the late season.

Winter barley (var. Pipkin) was harvested at 4 stages of growth : T1:250, T2:350, T3:450 and T4:550 gDM/kg, at the following dates : 25/5, 19/6, 3/7 and 11/7/1991, respectively. The chopped material from T1-T4 was stored in minisilos and from T1-T3 in larger silos for animal studies.

In comparison to steers bulls slaughtered at the same age have produced 14% more carcase gain and 20% more lean meat. Immunological castration which is reversible may reduce aggressive behaviour and maintain the performance advantages of bulls. Active immunization against luteinising hormone releasing hormone (LHRH) reduces LH and testosterone production and, therefore, aggression in bulls (Robertson et al. 1982). However, a controlled predictable response to vaccination has not been achieved. This may be due to suboptimal choice of a number of variables in the vaccination programme. This study investigated the effect of conjugate dose and age of the animal on the anti-LHRH antibody response in bulls.

Synthetic LHRH (UCB Bioproducts) was conjugated to keyhole limpet haemocyanin (KLH) (Sigma Chemical Company) using a modification of the novel carbodiimide method reported by Deen et al. (1990). New batches of conjugate were prepared for each vaccination. The efficiency of incorporation of radiolabelled LHRH varied between 40 and 45%.

The term pheromone is used to describe a substance that is produced by an animal and creates a response in other Individuals of the same species.

Reproduction in females can be affected by pheromones from other females in a number of mammals. This can invoke a degree of synchrony of oestrous cycles in for example the hamster (Handelmann et al, 1980) and the human (McClintock, 1971). Izard and Vandenberg (1983) demonstrated that in heifers which had their oestrous cycles synchronised using exogenous prostaglandin the degree of synchrony was enhanced when they were exposed to cervical mucus from cows in oestrus. They suggested that cervical mucus from cows in oestrus contains a pheromone which can enhance the degree of synchrony of oestrus in heifers.

The interval from calving to first oestrus (post-partum interval) is an important determinant of reproductive efficiency in suckler cows. While this interval is influenced by a range of factors including cow age, breed, presence of bull, cow-calf interactions and disease, the most important factors are suckling (frequency / number of calves) and nutrition (pre- and post-partum nutrient intake, body condition at calving and during early lactation). The mechanisms by which these factors, either independently or interactively, affect the length of the anoestrous period are unclear. Similarly, the time post-partum at which suckling exerts its effect on resumption of cyclicity is unknown. The effects of body condition score at calving and of changing the frequency of suckling on the length of the post-partum interval were determined. Preliminary results are presented.