The objectives of this experiment were to investigate the effect of adding a multi-enzyme product to a diet based on wheat, barley and soybean meal on faecal nutrient digestibility and nitrogen retention in early-weaned piglets.

A total of 36 pigs, weaned between 21 and 25 days of age, were assigned on weight and litter origin basis to two dietary treatments and placed in flat-deck pens of 6 pigs each. The design of the pens allowed total collection of urine and faeces separately.

While a considerable amount of information is available on the nutritional properties of rapeseed meal for ruminants, there is only limited information on its suitability and nutritive value as a feed ingredient for pigs. The objective of the present study was, therefore, to investigate the effect of feeding isonitrogenous diets containing rapeseed meals of different origins, but which varied in their glucosinolate content, to pigs. Thus, the effect of the level of dietary glucosinolates from rapeseed meal on the voluntary feed intake and performance of young pigs was investigated. Weaned piglets were chosen as the experimental model because of their sensitivity to unpleasant tastes, their high requirements for protein and their rapid response to the antinutritional components of feedstuffs.

Sheep breeding programmes for genetic improvement in carcass composition of terminal sires measure livewelght and ultrasonic backfat and muscle depths for inclusion in a selection index to predict genetic merit. Physiological traits which were genetically correlated with carcass traits could be incorporated into the selection index to increase the accuracy of selection and the rate of genetic improvement.

This study examined differences in physiological traits between lines selected for high or low carcass lean content. The measured physiological traits were chosen according to their role in protein and lipid metabolism : b-hydroxybutyrate (BHB) and glucose (GLUC) : indicators of energy balance; triglyceride (TRIG) and non-esterified fatty acids (NEFA) : intermediaries of lipid metabolism; UREA and creatinine (CREA) : indicators of nitrogen / amino acid metabolism and insulin-like growth factor-1 (IGF-1): an Indicator of growth hormone status.

Whilst it is well recognised that there is considerable within-breed variation in growth performance and body composition of cattle it is unusual for sire origin to be taken into account when designing nutritional studies. In planning an experiment on the effects of plane of nutrition and slaughter weight on the body composition and energy metabolism of Friesian steers it was recognised that the increased incidence of the Holstein gene pool in many AI bulls could have serious implications for interpretation of the results. Hence AI bulls of low Holstein content were identified and an attempt was made to obtain calves from a small number of bulls of uniform conformation.

Milk producers in the UK are paid according to their production of milk fat, protein and lactose and are also subject to a production quota which includes an element restricting fat production. The ability to predict the production of milk solids consequent on the feed inputs and animal state is therefore important. Results reported previously (Rook, Sutton and France, 1990) showed that multiple regressions of milk constituent yields on feed variables and animal characteristics such as parity and postcalving liveweight fitted poorly, with R2 ranging from 0.35 for lactose yield to 0.52 for protein yield. In practice, however, previous yields are often available and can be used to improve the fit of these empirical models. This study investigated the use of models including previous yields.

One assumption made by most users of the BLUP (Best Linear Unbiased Prediction) method to predict breeding values, is that variances are homogeneous over herds or herd-year-seasons (HYS). In dairy cattle there is abundant evidence, however, of heterogeneity of variance across herds or herd groups (see e.g. Hill et al. 1983 and Brotherstone and Hill, 1986, for U.K. studies). The effect of ignoring heterogenous variances between herds on prediction of breeding values for bulls may be small when using a sire model, if sires were tested across many herd-variance groups. Loss in efficiency may be larger when sires are tested in few herds, or, for cows, when the genetic evaluation is for bulls and cows simultaneously (with an animal model (AM)). The aim of this study was to calculate individual herd parameter estimates to investigate heterogeneity of within herd variance in the U.K. dairy population. The investigated trait was fat yield and the estimations were carried out using a REML (Restricted Maximum Likelihood; Patterson and Thompson, 1971) program written by Karin Meyer (Meyer, 1989).

Sire referencing schemes were first introduced in Australian sheep breeds with the aim, as the name suggests, of referencing sires used In different flocks, where the flocks tended to be large and sires tended to be selected from within the flock. However, sire referencing schemes can provide additional benefits when flock or herd size is small, since In this situation sires at least must be purchased from outside from other breeders to avoid problems of inbreeding; sire reference schemes help ensure that superior stock from other breeders can be identified objectively.

The recently developed technologies of genetic engineering offer the plant scientist not only a number of opportunities for introducing valuable novel characteristics into some of our crop plants but also provide for the first time the means to analyse and dissect some of the complexities of plant development and metabolism, and which will ultimately lead to even greater contributions to plant science.

At present the technology is still in an early phase of development. Methods of isolating particular genes and regulatory sequences are accelerating rapidly, as are the means of modifying them prior to their reintroduction into plants; the ability to culture cells and tissues in vitro are well established for a great number of species. Introducing the genes into plants cells is relatively easy for some species but remains very difficult as yet for others, including some of our most important crop plants; regenerating whole plants from cultured cells and tissues is similarly easy for some but difficult for others. However even at this early stage there are some remarkable achievements; the production of herbicide resistant plants by incorporating genes either from bacteria or from unrelated plants is one. Resistance to particular insects has been achieved by again incorporating a gene from a bacterium which codes for a toxin or one from a plant which codes for a naturally occurring compound toxic to insects. An achievement which may have even greater potential is that of the production of virus resistant plants; this is achieved by incorporating a part of the virus’ own genetic information into the plant. These achievements are already nearing commercial exploitation in some instances.

The objective of any livestock breeder is the identification of stock of superior genetic merit with respect to some goal for the production of future generations; their objective is the estimation of genetic merit. Traditional breeders achieve this simply by visual appraisal. Some breeders have realised the value of collection of performance records to make the assessment more objective. The animal’s performance record however results not only from the animal’s genetic make-up but also from the management and other non-genetic factors (age of dam, age of measurements) that it has experienced. Best Linear Unbiased Prediction (BLUP) is a method to estimate genetic merit (or breeding values) of animals. BLUP is universally regarded as the best method available to us to predict genetic merit of animals when performance records have been collected In a variety of herd, year, season and management environments. Considerable investment of time and money Is made in the organisation of unique animal identification and collection of records. It is therefore appropriate that maximum use is made of those records in the accurate prediction of genetic merit of individual animals.

Hormones play a vital role in promoting growth and in re-ordering metabolic priorities among tissues in a wide variety of physiological situations important to animal production. During pregnancy and lactation, however, the hormonal requirements for growth promotion in the developing infant seem diametrically opposed to those necessary within the mother for support of pregnancy and later for the provision of milk to the suckling young. Fetal endocrine autonomy clearly plays an essential role in protecting prenatal development. Despite this, fetal metabolism cannot be isolated altogether from that of the mother because of the need for maintained nutrient transfer to the conceptus. Indeed, hormones secreted by the fetal placenta into the maternal circulation appear to play important roles in manipulating maternal metabolism to favour transfer of metabolic substrates such as glucose to the conceptus. Similarly, alterations in the secretion of growth hormone during lactation have been considered to play an important homeorhetic role favouring transfer of substrate to the mammary gland for milk synthesis. However, many aspects of these adaptive changes remain uncertain.

Puberty in the female lamb may be defined as the time when a preovulatory follicle develops within the ovary, and secretes sufficient oestradiol as to activate the LH surge mechanism, and thus, trigger its own ovulation. The development of the ovarian follicle results from a marked increase in the frequency of episodic luteinisincg hormone (LH) secretion from the pituitary gland (1). This probably reflects increased secretion of gonadotrophin-releasing hormone (GnRH) from the hypothalamus; studies in adult female sheep have demonstrated that pulses of LH in the peripheral circulation correlate with peaks of GnRH in the hypothalamic portal /circulation (2). In the Suffolk sheep, a very seasonal breed, changes in photoperiod provide a precise time cue to initiate reproduction (3). Under natural conditions, the autumnal decrease in daylength triggers puberty at ~30 weeks of age (4). In other breeds, the introduction of mature rams may also be important in triggering puberty. However, photoperiod and social cues can only induce puberty if appropriate growth has occurred (1, 4). Traditionally, a critical body weight or composition has been considered necessary for puberty. Although changes in body weight and composition may be good correlates of puberty, this notion neglects to consider the actual mechansim by which the brain percieves somatic changes. An alternative viewpoint is that the brain monitors and responds to changing concentrations of blood-borne metabolites or metabolic hormones or some other aspect of metabolism during development, and uses this information to trigger enhanced GnRH secretion. To investigate the mechanisms by which the central nervous system monitors somatic development, we have developed an experimental model in which growth is retarded by means of dietary restriction (4,5). Suffolk lambs are placed on low nutrition at weaning at ~8 weeks of age. The diet provides 25-50% of the caloric intake for a normally growing lamb at 20 kg, with water, minerals and vitamins ad libitum. Although the lambs remain active and healthy, growth is slowed, and eventually plateaud at ~20 kg. Puberty is markedly delayed beyond the normal 30 weeks of age in such lambs. If the lambs are ovariectomised (OVX), LH secretion remains low, indicating that the hypogonadotrophic state does not arise from enhanced responsiveness to ovarian steroid negative feedback (4, 5). Exogenous GnRH at physiological doses (2.5 ng/kg BW) can induce LH and FSH secretion, indicating that the pituitary gland is capable of adequate function (5).

In any cattle production system, reproductive performance is of central importance. The output from beef cow systems is calves, while lactation in the dairy cow is only achieved following parturition. On a world basis, the major cause of poor reproductive performance is inadequate nutrition, and in most cases this is represented by an inadequate energy supply, although in specific circumstances particular vitamin, mineral or disease problems can occur. This review considers how nutrition, and in particular energy nutrition may act via the endocrine system to influence reproductive performance in cows. The paper will consider the post-partum anoestrous period, fertilization and embryo mortality.

It is now known that growing pigs can utilise considerable quantities of non-starch polysaccharides (NSP) in their diets (Bulman et al., 1989). These materials are fermented in the hind-gut of the animal to produce volatile fatty acids (VFAs) which are then used as an energy source, unlike starch from conventional cereal-based rations which is digested by the host enzymes of the animals. Little is known about how animals adjust to a sudden change in dietary energy source and the present experiments were designed to investigate the metabolic adaptations in pigs fed either a conventional cereal-based diet or one containing 300 g sugar beet pulp/kg diet.

Insulin-like growth factor-1 (IGF-1) stimulates many anabolic processes within the body. In entire animals, release of IGF-1 has been shown to be regulated by nutritional status (e.g. starvation/re-feeding) and in reproductive tissues by gonadotropins and steroid hormones (Phillips et al., 1990). To investigate this further the relation between serum IGF-1 and N retention has been studied in entire and castrated pigs at different planes of nutrition and stages of growth.

Continued improvement through genetic selection and the use of entire males has resulted in pigs with considerable potential for lean tissue growth rate. These animals have, however, lower appetites and this suggests that there may be considerable differences in the partition and in the efficiency of utilisation of dietary nutrients, compared with those previously recommended by ARC (1981). There may also be differences in energy expenditure since Campbell and Taverner (1988) and Rao and McCracken (1990) have suggested that animals of high potential for lean tissue growth rate have higher maintenance energy requirements. There is little information on the energy requirements of pigs of different growth potential and the present experiments were designed to evaluate the effects of feeding levels on nutrient partition and energy metabolism of pigs of different body weights and sex.

Sulphydryl (SH) groups and disulphide bonds are important in maintaining the structure and functional properties of food proteins. They play an important role in the formation of relatively rigid complexes as in protein gels and doughs. Heating affects the proportion of cysteine/cystine residues (ie. SH/S-S groups, respectively) and has also been found to reduce protein utilisation by animals. It has been postulated from studies which utilised fish protein that heat induced S-S linkages from SH group oxidation hamper the action of proteolytic enzymes and cause a reduction in protein and amino acid digestibility (Opstvedt et al.,1984). An examination of literature data on pigs also show that the amino acid cystine, is often among the least digestible amino acids. Secondly, proteins that are typically high in cystine or S-S bond content such as blood, feather and hair meals, are all known to have low in-vitro or in-vivo nitrogen digestibilities.

The development and improvement in processing technology in recent times has resulted in considerable reduction in trypsin inhibitors and enhancement of protein quality of full-fat soyabeans (FFSB) thus leading to their increased use in relation to soyabean meal (SBM) in animal diets. This study was designed to provide information on the relative nutritive values of the various soya products for their effective use in diet formulation.

Scrapie-like diseases occur in sheep, goats, cattle, and other ruminants, in mink, and in man. An identical disease has now been seen in cats. There are no in vitro laboratory tests of infection which thus can only me recognised clinically, neuropathologically, with tedious animal transmissions, and by finding an altered host protein, called PrP, electrophoretically or ultrastructurally. There is no immunity in these diseases, due to an absence of infection-specific antigens, Assays of infection depend on incubation period measurements in mice infected intracerebrally with serial dilutions of infective sources. Dilution of different strains or isolates, or of single strains in different host genotypes, or using different routes of infection, result in distinct dose-response curves (incubation period/infecting dose).

Legislation to control veterinary medicinal products is undergoing continual development in the EEC and UK and therefore the risks are continually reassessed. In the present paper current and future legislation together with consumer concerns both real and imaginary are reviewed.

Since the EEC ban on hormonal growth promoter implants in 1986 the remaining legal products are all feed additives. Registration of feed additives in the EEC is controlled under Directive 70/524 and its various amending directives. this directive is concerned with all products added to feed and mainly includes substances used to affect the quality of the feedstuff i.e., emulsifiers, stabilisers, antioxidants, colorants and binding agents and also vitamins and micronutrients. The majority of growth promoters exert their affects by antimicrobial activity and these and certain prophylactic medicinal products such as coccidiostats are also included. All products with a therapeutic action are controlled under the Veterinary Medicine Directives 81/851 and 81/852, quite separate legislation and under the responsibility of a different department within the EEC Coimdssion. However, there is provision under Directive 84/587 amending 70/524 to transfer the medicinal feed additives to 81/851 and 81/852.

The use of barley and a protein supplement as a system for intensively finishing calves for beef has been widely used commercially since Preston, Whitelaw, Aitken, MacDermaid and Charleson (1963) originally developed the concept. Once the basic requirements for protein and energy were established the concern of researchers turned to how these requirements could be met at minimal cost. Obviously the most profitable combination of ingredients depends on the prices prevailing at the time, but a variety of raw materials, which may be used to cheapen intensive cereal rations, have been tried experimentally. In the present study the effects of using rapeseed meal (RSM) or maize gluten (MG) as protein supplements to either barley (B) or wheat (W) on the growth and carcass characteristics of Charolais cross Friesian bulls were assessed. The wider availability of double low rapeseed meal (low in both erucic acid and glucosinolates) and maize gluten, combined with their relative cheapness, has made them attractive raw materials for inclusion in ruminant feeds.