Incorparating dry feed materials such as molassed sugar beet pulp with grass at ensiling has been shown to reduce effluent production (Jones et al. 1990) and improve silage fermentation (Offer and Al-Rwidah,1989). Jones and Jones (1988) observed higher liveweight gains in beef steers fed silage produced by ensiling grass with molassed sugarbeet pulp compared to animals fed the same quantity of beet pulp, mixed with silage produced from untreated grass, at the point of feeding. Ferris and Mayne (1990) observed that milk output per unit of grass ensiled was similar for cows offered diets in which a given quantity of sugar beet pulp was either included with grass at eniling or offered as a supplement with untreated grass silage.The objective of the present study was to examine the possible use of molassed sugar beet pulp fed either separately or ensiled with grass at the time of silage making on ewe and lamb performance.

The use of fodder beet in rations fed to cattle and sheep has always been valued highly. Recent long-term experiments have shown that the palatability and high feeding value of fodder beet is fully preserved during the ensiling process.The objective of this experiment was to evaluate the performance of ewes in late pregnancy when fed either whole crop fodderbeet silage or grass silage.

Mature (2-7 yrs), oestrous synchronised, twin bearing ewes (n=60) of mixed breeds (mainly Suffolk cross, greyface and halfbred), were selected following winter shearing and pregnancy scanning in December. At ten weeks prior to the predicted mean lambing date, the ewes were allocated to one of two treatment groups which were balanced for breed, age and liveweight. High quality precission chopped silage (DM 194 g/kg; CP 152 g/kg DM; in vivo ME 12.8 MJ/kg DM) and whole crop fodderbeet silage (WCFB)(DM 171 g/kg; CP126 g/kg DM; in vivo ME 11.7 MJ/kg DM) were fed in Tl and T2 respectively.

Feeding cattle is an operational process where such factors as the size and range of the animals, the nature of the feed, the design and robustness of the feed barriers and troughs and the man doing the feeding task all contribute to its efficiency. In two trials reported here three types of feed barrier, dovetail, tombstone and diagonal, were compared and their troughs were varied in height. A previous trial (Petchey and Abdulkader, 1991) indicated that food wastage was significantly (P<0.05) greater from a post-and-rail barrier. The third trial was to examine the effect of varying the central rail and trough height on the efficiency of the post-and-rail barrier.

Each of the experimental barriers was movable 2.7 m long and positioned across the front of the experimental pens. Each trough could be varied in height. The trials had a Latin square design. In trials 1 and 2 there were three Friesian heifers and two Hereford x Friesian cows in each group respectively. Trial 3 had three Friesian heifers in each group. The mean values for the nine heifers, six cows and nine heifers in trial 1,2 and 3 respectively are given in Table 1.

Previous research has shown that social dominance in dairy herds can be measured using replacements of one cow by another at feed stations (Rutter et al,1987). When there is competition for feed or space, the motivation to engage in physical and non-physical agonistic interactions will be stronger than if resources are freely available. When resources are limited, social dominance becomes very important and high ranking animals have priority.

This becomes especially important after cows are returned from milking and/or when fresh feed is added when the number of cows is far greater than the number of feeding spaces (Campling and Morgan, 1981). This experiment aimed to further investigate the way in which social interaction between cows affects the feeding behaviour, particularly at times of peak feeding activity.

Many of the effects of growth hormone are now thought to be mediated via the stimulation of insulin-like growth factor-I (IGF-I) production by many tissues, especially the liver, with this stimulation being dependent upon the presence of the GH-receptor (GHR). IGF-I gene expression occurs via alternative promoters giving rise to class 1 and 2 transcripts, of which class 2 is thought to be preferentially responsive to GH (Saunders, Dickson, Pell & Gilmour, 1991).The effects of IGF-I include the stimulation of DNA synthesis (mitogenesis) and protein synthesis in most cell types, together with the differentiation of many cell types into mature tissue, including the differentiation of muscle cells into muscle fibres. Thus the GH/IGF-I axis has been found to play a major part in the control of animal growth. For this reason, we studied the age related changes in IGF-I and GHR mRNA expression in pig liver and skeletal muscle.

In non-ruminant livestock the energy which can be derived from dietary cellulose and xylan is limited by the inefficient microbial fermentation of these polymers in the hind-gut. Furthermore, in poultry, cereal-derived plant structural polysaccharides impair normal digestive function through the formation of gel-like structures that trap nutrients which are therefore unavailable to the animal. The nutrition of non-ruminant livestock could be significantly improved by the depolymerization of plant structural polysaccharides, through the introduction of cellulase activity in the small intestines of these animals. This report describes the generation of transgenic animals with the capacity to express and secrete a functional endoglucanase from the exocrine pancreas.

The gene encoding endoglucanase E (celE) from Clostridium thermocellum was fused to the exocrine pancreas specific enhancer of the elastase I gene and the (β-globin polyadenylation signal, and used to create 14 lines of transgenic mice. A range of tissues were assayed for cellulase activity, using β-glucan and 4-methylumbelliferyl-β-D-cellobioside as substrates. The pancreas was also subjected to immunohistochemistry and in situ hybridization.

Plant structural polysaccharides provide a major source of nutrient for ruminant livestock. These carbohydrates are not degraded by mammalian-derived enzymes, but are hydrolysed by rumen microbial plant cell wall hydrolases. In view of the pivotal role of microbial cellulases and xylanases in ruminant nutrition, there has been considerable interest in these enzymes. In this paper we wish to illustrate how recombinant DNA (rDNA) technology can be utilised to dissect the biochemistry and molecular architecture of these enzymes, and provides us with the opportunity of generating novel cellulases and xylanases with increased capacity to hydrolyse the plant cell wall.

In general cellulases and xylanases from anaerobic microbes associate into large molecular weight complexes, whose integral structures are responsible for the efficient hydrolysis of plant structural polysaccharides. The feasibility of altering these complexes, or transferring them to other organisms represents a significant challenge.

Silage inoculants consisting of primarily Lactobacillus plantarum, are widely used to ensure that lactic acid bacteria dominate the fermentation of water soluble carbohydrates (WSC) during the ensilage process. Previous studies have shown that the supplementation of ensiled forage crops with cellulases can also improve the quality of silage through i) increasing the generation of WSC, and therefore ensuring an adequate supply of substrate for L. plantanim; ii) Partial hydrolysis of the plant cell wall increasing the rate of cellulose hydrolysis within the rumen. From the above discussion it is apparent that the use of an L.plantarum strain, with the capacity to hydrolyse cellulose, could be beneficial in the ensiling process. No celluloytic lactic bacterium has been isolated from microbial ecosystems. However, the advent of recombinant DNA technology affords us the possibility of engineering a cellulolytic derivative of L. plantarum. This report describes progress towards this objective.

There have been many attempts to separate X- and Y-chromosome bearing spermatozoa on the basis of surface charge or density (Schröder, 1941; Bhattacharya et at., 1966; Engelman et al., 1988; Blottner et al., 1992). These have not met with universally accepted success. More recently, sorting has been achieved using the flow cytometer (FACS) to discriminate between the very small differences (3-4%) in DNA content of X- and Y-bearing spermatozoa (Johnson et al., 1989; Cran et al., 1993). However, the spermatozoa must be ‘flat headed’ e.g. rabbit, chinchilla, horse, pig, cattle and sheep.

The flow cytometer (fitted with a U.V. laser) was adapted to accept a bevelled inlet tube. This gave us a ‘ribbon-like’ profile of the sample stream which forced the spermatozoa into a specific orientation.

Semen was collected from healthy bulls of proven fertility and within 1/2 hr. was diluted to 1 x 107 per ml. and stained with Hoechst 33342 (5-10/μm) for 1 hr. at 35°C. Only those spermatozoa emerging from the 70μ nozzle that were edge-on to the 90° detector were selected as X or Y by the 0° detector. Gated intact spermatozoa were positioned into individual drops and then charged positive or negative for later deflection and collection into tubes containing egg yolk medium.

A map of the bovine genome will be an important tool for identifying genes causing congenital defects, and those controlling disease susceptibility and production traits in both beef and dairy cattle. Over 300 genes have already been mapped and a low resolution map should be available within two years. We are actively involved in the EC funded European Bovine Genome Mapping Group. To date our work has involved the development of markers and studies of experimental designs, two necessary precursors of a large scale bovine genome mapping project. In this article we briefly describe ongoing projects underpinning and improving the prospects for mapping bovine genes affecting disease and production.

For a linkage map of the bovine genome to be of use, the markers should display high levels of polymorphism. The most common markers on the map of the human genome are restriction fragment length polymorphisms (RFLPs), however these are usually diallelic, often with one allele at high frequency. We have been concentrating our efforts on the production of a relatively new class of marker, the micro-satellite.

There is a multitude of physiological and metabolic effects that could occur in animals fed ß adrenergic agonists. Many of these could contribute directly or indirectly to the repartitioning effect. ß-agonists are known to stimulate muscle hypertrophy at least partially by reducing the rate of myofibrillar degradation. It is presumed that the changes in muscle growth are associated with changes in the calpain system, which includes the calpain specific inhibitor, calpastatm. Parr et al., (1992) demonstrated a significant effect of ß agonist treatment on calpastatin gene expression in cattle when measurements were made on day 42 of treatment. The present study was conducted to assess the acute and chronic effects of ß; agonist treatment on muscle growth and calpastatin (both in terms of gene expression and enzyme activity), the interpretation of which would provide an insight into the role of the calpain system in muscle growth.

The rate of milk secretion is controlled acutely by the frequency and completeness of milk removal from the mammary gland. Numerous experiments in dairy animals have shown that this acute control is exerted locally within each gland, rather than by circulating galactopoietic hormones (Wilde & Peaker, 1990). Local regulation of milk secretion by milk removal is not related to physical distension of the gland by accumulated milk (Henderson & Peaker, 1984), but is instead the result of changes in the degree of chemical feedback inhibition exerted by a secreted milk constituent.

Proteins that may act as feedback inhibitors of lactation (FIL) have been isolated from goat's milk (Addey et al, 1991a), cow's milk (Addey et al, 1991b) and human milk (Wilde, unpublished work) on the basis of their ability to inhibit synthesis of milk constituents in a rabbit tissue explant bioassay (Wilde et al, 1987a).

Yucca schidigera extracts have been reported to reduce noxious gases such as ammonia in animal rearing facilities when incorporated into the diet. Ammonia reduction effects have been hypothesised to be due to inhibition of microbial urease by the extract The effect of a commercial extract, (De-Odorase, Alltech Inc., Nicholasville, Kentucky, U.S.A.), on the activity of urease enzyme from Bacillus pasteurii was determined by measuring the ammonia generated from the breakdown of urea using a modified Berthelot assay. The basis of this assay is the reaction of ammonia, hypochlorite and phenol to give phenolindophenol dye which can be measured colorimetrically. The use of trichloroacetic acid as a stopping reagent allowed addition of extract to controls and standards after enzyme reaction but before colour development. As ionic strength has been reported to affect the activity of certain ureases, it was fixed at 0.90 for all enzyme reactions. Subsaturating substrate concentrations (5 mM) were employed to mimic in vivo conditions. Reaction velocity was measured over the pH range 3.0 to 8.5 in 170 mM potassium citrate, potassium phosphate and potassium HEPES buffers in 0.4% extract (40 times typical dosage). Over the active pH range of the enzyme no significant differences between control and analytical urease activities were observed (P > 0.10). Phosphate strongly inhibited this particular urease, as has been reported for C.ensformis urease and was deemed unsuitable for such assays. We conclude that it is very unlikely that Y.schidigera extracts function as urease inhibitors either in vitro or in vivo.

Lactobacilli have been shown to inhabit the proximal regions of the digestive tract of many species of animals, and some of these lactobacilli have the ability to adhere to and colonise the epithelium of the oesophagus (Tannock, Blummershine and Archibald, 1987) and stomach (Fuller and Turvey, 1971; Tannock et al., 1982), whilst others appear to be associated with the small intestine (Tannock et al., 1982). The mechanisms by which these bacteria colonise their habitats is still unclear.In this study the adhesion of lactobacilli, isolated from the small intestine of pigs, to porcine small intestinal cells was investigated.

Polyunsaturated fatty acids(PUFA) are vitally important for normal neonatal development. As well as providing a source of energy they are intrinsically involved in the establishment and maintenance of cell membrane structure and function. High PUFA levels, however, are subject to peroxidation and consequently require to be protected against free radical attack via an adequate antioxidant supply. The avian embryo was used as a model system as it is particularly dependent on PUFA and poor hatchability has recently been linked to inadequate PUFA metabolism. The micronutrient elements Se, Cu, Zn, Fe and Mn are involved in the antioxidant complex through their presence in the enzymes glutathione peroxidase (GSH-PX), superoxide dismutases (SOD) and catalase. The concentrations of these elements were measured in eggs and in chick embryonic and post hatch brains at different stages of development in order to elucidate their roles in the maintenance of PUFA metabolism.

Broiler diets are routinely supplemented with approximately 50 g/kg lipid. The lipid supplement used in the UK has been a blend of tallow and vegetable oil, however, there is considerable interest in the use of alternative fat sources. The fatty acid composition of supplemental lipids, in particular the degree of unsaturation of fatty acids can (1) effect lipid digestibility and may be reflected in differences in growth performance and (2) markedly influence tissue fatty acid profiles which may increase the requirement dietary antioxidant supply and affect meat storage characteristics.

Full-fat low glucosinolate rapeseed has been included safely in, broiler diets, at 10-20% (Leeson et al., 1978), and at 20% (Lee et al., 1991). Full-fat low glucosinolate rapeseed (21 % crude protein (N X 6.25) and 39% oil), milled with field bean (26% crude protein), produce a dietary component which has good physical handling qualities, high protein content (24% CP), with a reasonable balance of amino acids, and moderate oil content (21%). We conducted an experiment to study the ability of broiler chickens to utilize the milled mixture (1:1) of rapeseed and field beans (RB), included at different dietary levels. The study considered; bird performance, nitrogen and fat utilization, pancreas and liver weights, trypsin and a-amylase in jejunal digesta and the pancreas, and plasma thyroxine concentration.

The metabolisabie protein system (AFRC, 1992) requires the measurement of the dynamics of the degradation of protein in the rumen. However the recommended method, using fistulated animals, is slow, expensive and may be considered unacceptable by many in terms of animal welfare. The objective of this work was to develop an in vitro technique for the routine assessment of feed protein degradability.

A 101 vessel fitted with an automatic stirrer was filled with modified van Soest media and rumen liquor (pooled from two sheep) and maintained under anaerobic conditions at 39.5°C. Small artificial fibre bags (4.5x3cm, pore size 54 micro-m ±4) were filled with 0.4g of soya bean meal and incubated in the vessel for 3,6,10 and 24 hours using 3 replicates at each time. Bags were washed in running cold water for 30 mins immediately after removal. Four replicates of 3g samples in large Dacron bags (10x7cm, pore size 55 micro-m ±22) were also incubated in sacco in fistulated yearling wethers using a 4x4 Latin square design to assess the base line degradability. In sacco bags were rinsed and frozen after removal and washed in a domestic washing machine at the end of the experiment.

The metabolisable protein system (AFRC, 1992) requires the measurement of the dynamics of the degradation of protein in the rumen. However many drying techniques used during sample preparation cause protein damage and denaturation which may affect the subsequent assessment. The objective of this work was to compare the dry matter and nitrogen degradation profiles of samples of grass silage dried using a range of techniques.

One kilogram samples of first cut grass (Lolium perenne) silage (156 g CP/kg DM) were air dried (AD), freeze dried (FD), dried at 50 (OD50) or 100°C (OD100) in a still air oven or dried in a microwave oven (MD) on the ‘defrost’ setting. In sacco degradability was assessed in fistulated yearling wether sheep, using a 5x5 Latin square and incubation times of 3,6,12,24 and 48 hours. Bags size was nn x nn cm with a sample size of 3 g. Bags were rinsed and frozen upon removal, mechanically washed and dried at 60°C before analysis. Dry matter and nitrogen disappearance data for each sheep was fitted to the model y = a + b(1-e-ct) using non-linear regression.

A technique involving the measurement of the gas production from the microbial fermentation of a specified substrate in sealed conditions has recently been proposed as a method of assessing the fermentation kinetics of tropical feeds (Theodorou et al, 1992). The objective of this work was to determine if such a technique could be used to assess the dry matter degradability of protein supplements.

1g air dried feed samples were placed with 95 ml of modified van Soest media and 5 ml of strained rumen liquor in 150 ml serum bottles and sealed under anaerobic conditions. Five replicates of soya bean meal (SBM), fish meal (FM), rape seed meal (RSM) and winter beans (WB) were set up together with control blanks that lacked the test feed. Bottles were incubated at 39.5°C for a 96 hour period and gas production volume measured at regular intervals. Cumulative gas production was corrected for the blanks and sample dry matter and plotted against time.