Nitrogen losses following application of pig slurry to grassland represent not only a loss of available N for plant growth, but also a source of air and water pollution by ammonia volatilization, denitrification and nitrate leaching. Previous small scale experiments showed that by reducing the crude protein content of the pigs diet, the slurry nitrogen content was also reduced (Hobbs et al., in press). The aim of this study was to investigate the nitrogen uptake by herbage and losses to the environment following application to grassland of slurry from pigs fed a reduced crude protein diet.

Whereas feed enzymes containing (β-glucanase give good responses in broilers and young pigs those in older pigs have been variable (Campbell and Belford, 1992). In commercial practice, bushel weight is frequently used as an indicator of quality. There are a range of methods for determining ileal digestibility of diets each of which has limitations (Fuller, 1991). Previously in our laboratory the 'T' cannula (T) method has been used, but the post-valve 'T' caecal (PVTC) cannulation method (van Leeuwen et al, 1991) appears to have a number of advantages. The twin objectives of this study were to study the effects of a feed enzyme preparation in two sources of barley of different bushel weight and to compare the T and PVTC methods with diets of differing fibre content.

Field observations suggest an increased incidence of digestive disorders (e.g. non-specific colitis) when growing pigs are offered diets containing high levels of wheat, particularly when the diet is offered in pellet rather than in meal form. This may be due to the anti-nutritive effects of wheat non-starch polysaccharides, with the possibility that such effects are increased following diet processing. Additionally, the provocative effects of wheat on digestive disorders may involve a change in gut microbial balance, which in turn may influence the production of fermentation end products such as skatole. High skatole concentrations (> 0.2 ppm) in carcass fat can adversely influence the sensory quality of pig meat. In this study the aim was to evaluate the effect of diet processing and feed enzyme (xylanase) supplementation of wheat based diets on the performance, general health and carcass skatole levels in growing pigs.

While the efficacy of appropriate fibre-degrading enzymes in poultry diets has been well established, much less data exist to support the economic use of exogenous hydrolytic enzymes in pig diets. This trial was conducted to assess the effects of one such fibre-degrading enzyme, β-glucanase (1,3-(l ,3; 1,4)-β-D-Grocan 3(4)-glucanohydrolase, Allzyme BG), added at graded levels of 0, 500, 1000 and 2000 ppm to a barley-based piglet diet, on a variety of production characteristics.

There is much current interest in the potential of suitable in-feed enzymes to improve digestibility and productive performance in pigs. However, in order to improve the nutritional value of feed by enzyme supplementation it is important to match enzyme characteristics to both the substrates present and the animal species concerned. The main antinutritive factors in wheat are arabinoxylans and they comprise over 50% of the total NSP's in the whole grain. Since monogastric animals do not possess the endogenous enzymes to break down the cell wall structures of wheat, which consist mainly of arabinoxylans, the addition of xylan degrading enzymes should be considered. Therefore, a growth trial in weaner pigs was conducted to evaluate the effect of supplementing a pelleted wheat/soya - based diet with two different xylanase sources (Trichoderma spp.), provided at the same activity levels in a premix (xyl#l and xyl#2). A third enzyme treatment incorporated the same level of xyl#l in conjunction with a protease (pro) obtained from Bacillus subtilis.

It is well established that the fatty acid combustion of adipose issue in pigs (non-ruminants) may be manipulated by changes in the fatty acid profile of the diets. The objective of this program of work was to quantify the responses of adipose depots of finishing pigs to changes in the level and profile of dietary fatty acids and to relate these changes to the sensory quality of meat as determined by taste panel.

Variability in the rate of postmortem meat tenderisation occurs in the carcasses of pigs, even those of similar genotype raised under common conditions (Koohmaraie et al, 1995). Recent work has shown that administration of synthetic (β-agonists enhances muscle growth, reduces tenderisation and increases the activity of calpastatin, the natural inhibitor of the proteolytic enzymes μ-calpain and m-calpain, after slaughter (Kretchmar et al., 1990, Parr et al., 1992). Therefore, it is possible that part of the above variability may be related to levels of natural β-agonists, i.e. adrenaline. In this study the relationship between pigmeat toughness and the calpain proteolytic system has been investigated, using adrenaline infusion in an attempt to perturb the calpain system and create a wide range of meat qualities.

The reduction in the mean backfat thickness of pigs that has occurred in the UK since a national pig carcass classification scheme was introduced in 1971 has shifted the distribution of P2 depths leading to a marked increase in the number of extremely lean pigs slaughtered. This trend in leaner pork has been accompanied by critical comment from the meat industry, particularly retail butchers, regarding the increasing incidence of meat quality problems among the ultra-lean carcasses at the leading edge of the frequency distribution. The complaints are of poor cutting, presentational and processing qualities and suggest that the flavour, juiciness and tenderness (eating quality) of meat from modern lean hybrids is lower than that from pigs produced some 20-30 years ago.

Eating quality is an important aspect of carcass value but it is difficult to measure. Trained taste panels are the only realistic option but results are sometimes variable. As part of a larger study into the design of taste panels tests in commercial situations, this work has examined differences between panellists.

Fresh grass is a highly variable product, which is generally characterised as having a high crude protein content, with a high rate and extent of degradation in the rumen. For lactating ruminants, this may result in an effective rumen degradable protein: fermentable metabolisable energy (ERDP:FME) ratio in excess of the optimum requirement for microbial growth, leading to inefficient nitrogen utilisation and high levels of urinary nitrogen excretion. One method of improving the efficiency of nitrogen utilisation is the use of supplements. An appropriate supplement should optimise ERDP and FME supply to the rumen and provide sufficient metabolisable protein (MP) to balance animal requirements. The objective of the experiment was to investigate the response of lactating ewes offered grazed grass to variations in ERDP:FME ratio and digestible undegradable protein (DUP) supply from concentrate supplements.

To develop sustainable grazing systems based on mixed plant species communities, it is important to know how much and from which species animals eat. Previous studies have shown that sheep have a preference for about 70% clover in their diet, when offered a choice between grass and clover at the same sward surface height, 6cm SSH, (Parsons et al, 1994). The objective of this experiment was to establish whether grazing sheep altered their preference for ryegrass (Lolium perenne) and white clover (Trifolium repens) in response to variation in the relative vertical availability of the grass and clover.

The objective was to identify the long term consequence of two extreme scales of spatial heterogeneity of perennial ryegrass and white clover on the diet selected by sheep, together with plant to plant species competition and hence sward composition. Large patches (ie highly aggregated swards) offer minimum between plant species competition, but maximum likelihood of selection by the grazing animals, whereas a fine mixture of two plant species provides maximum between plant species competition and reduced opportunity for selection by the grazing animals.

Formulation of diets mat are synchronous for the hourly energy and nitrogen release in the rumen increase the efficiency of microbial protein synthesis (Sinclair et al,1993). However few trials have been conducted that have investigated whether this is translated into a whole animal production response. Rate of degradation of energy and nitrogen (N) components of feeds have been classified as fast, medium or stow (Johnson, 1976). Diets containing high proportions of quickly degradable nitrogen but low amounts of quickly fermentable carbohydrate result in an uncoupling of fermentation decreasing the efficiency of use of dietary nutrients (Rooke et al., 1987). The objective of the experiment was to study the effects of synchronising the rate of energy and nitrogen supply to the rumen in diets with two rates of carbohydrate release on growth and metabolism in ewe lambs.

Feed is the major cost of indoor lamb production, it accounts for up to £12/lamb reared (MLC, 1994) which is equivalent to 23% of the output value. Most intensively produced lambs are fed expensive specially formulated lamb creep diets. The aim of this experiment was to evaluate the effect varying the proportions of the starch (barley, WB) and digestible fibre (dried molassed sugar beet feed; SBF) and a protein pellet compared to a commercial lamb creep (LC) on lamb physical and financial performance.

180 early weaned lambs, (weaned at 6 weeks of age), weighing on average 17.5 kg liveweight were allocated to one of six treatments; 0% SBF, 20% SBF, 40% SBF, 60% SBF, 80% SBF and LC. Each diet contained 20% protein balancer pellets with the remainder being whole barley. The LC diet was offered alone.

Addition of sewage sludge to grassland may be reflected in ingestion of lead by animals with implications for the human food chain. The research reported here was part of a series of experiments conducted to investigate the possible risk to the health of livestock and humans associated with the use of sewage sludge in agriculture. The transfer of several elements to the body tissues of lambs was examined, including that of cadmium, copper, zinc and lead. The results for lead are reported in this paper.

Weaned Kent lambs (6/treatment, 20 to 45 kg liveweight) were given dried grass ad libitum (Trial 1, indoor feeding) either as the sole feed (C) or with 100 g/kg DM of one of two soils (CM, sandy -pH 6.18; or RM, a calcareous loam - pH 7.55) which had been amended historically with sewage sludge and which contained 102 (CM) and 130 (RM) mg Pb/kg DM.

This trial sought to increase the knowledge of the changes in the endocrine status of male sheep as they mature, and to link this with sexual and agonistic behaviour when they are reared in the presence or absence of females from weaning.

80 twin-reared Suffolk x Mule lambs were selected at birth. 32 of the male lambs were castrated (C) and 32 were left entire (E); there were 16 female lambs (F). The ewes were stocked at a rate of 20 ewes per hectare. The lambs were weaned at 12 weeks of age in late June, when they were separated into two groups. The first group (+F) comprised 16 entire males, 16 castrated males and 16 females that were run together until the end of July. Thereafter, raddled vasectomized rams were run with the ewe lambs to show when the first oestrous cycles occurred.

Testosterone levels are generally higher in entire male sheep when photoperiod is short as this coincides with the mating period and oestrous cycles of the female. This may increase management problems of entire male sheep through augmented agonistic and sexual behaviour. By delaying puberty in the entire male lamb, management problems may be avoided, while retaining the full benefits of some testosterone secretion to promote growth and leanness. This experiment was initiated to examine the possibility that lamb growth will be enhanced under either constant long or constant short photoperiod without increased behavioural problems.

At birth (mean birth date 19 March 1994 ± 3 days), 24 twin male lambs were assigned as pairs to either long (L) or short (S) photoperiod treatments alternately. One lamb from each pair was left entire (E) and the other lamb was castrated (C) at 12 hours of age using elastrator bands.

Feeding lambs a single ration, with a fixed protein:energy ratio, from weaning until slaughter will incur inefficiencies of protein utilisation if protein requirements (relative to energy requirements) vary with stage of growth. Kyriazakis and Oldham (1992) have demonstrated the ability of sheep to select systematically between diets of low and high protein content. The objective of this experiment was to use a choice-feeding methodology to identify optimum dietary protein concentrations at different stages of lamb growth.

Eighty Suffolk cross-bred lambs were weaned at 6 weeks of age, blocked by sex and then live weight and allocated at random (within block) amongst 16 pens. Pens were allocated at random to one of two dietary regimens: SINGLE (concentrate containing 200g CP/kg as-fed) or CHOICE (free choice between concentrates containing 170 or 230g CP/kg as-fed).

A variety of in vitro methods have been developed to characterise feeds. For routine analysis, any such method needs to be relatively rapid, cheap and reproducible, as well as providing data that may enable the accurate prediction of animal performance (Graham, 1993). The objective of this experiment was to determine which of a number of methods of feed characterisation best predicted the observed daily liveweight gain of ewe lambs fed those feeds.

The feeds used in this experiment were grass silage, (GS), molassed sugarbeet feed (MSBF), citrus pulp (CIT), wheat distillers' grains (WDG) and fishmeal (FM). Forty ewe lambs were randomly allocated between four groups and fed GS (0.7 kg DM/d) supplemented with either MSBF/FM, MSBF/WDG, CIT/WDG or CIT/FM.

Lamb consumption has fallen steadily over the past 40 years, partly due to the consumer's belief that it is an over-fat meat. In general, there are two approaches to solving this problem of excess fat. Firstly, to identify and breed from sheep that are genetically leaner. Secondly, to modify the feeding strategy to produce a leaner product. If an interaction between the genotype - either breeds or lines within breeds - and diet exists, establishing methods for linking selection and feeding programmes becomes a priority. In the first year of a programme investigating genotype by dietary interactions in sheep, the effect of non-limiting and limiting foods on growth rate, feed efficiency and body composition in ewe lambs from a line of Suffolk sheep was evaluated indoors.