Synchronising the rate of rumen breakdown and availability of dietary energy and nitrogenous components can improve the capture of rumen degradable nitrogen and improve the amount and efficiency of rumen microbial protein synthesis. It is not clear what influence rumen synchrony has on nutrient use by the portal-drained viscera (PDV). This experiment has examined the impact of feeding two diets formulated to be asynchronous or synchronous with respect to the potential hourly supply of energy and nitrogen to the microbial fraction of the rumen on portal blood flow, net flux of ammonia and urea across the PDV and arterial insulin concentrations.

Formulation of diets that are synchronous for hourly energy and nitrogen (N) release in the rumen has been shown to increase the efficiency of microbial protein synthesis (MPS) in the rumen (Sinclair et al. 1995). However diets formulated to be synchronous for hourly release of energy and N did not improve the whole body N efficiency of male lambs (Witt et al. 19%) but there were indications of possible differences in energy metabolism between animals offered synchronous or asynchronous diets. The objectives of the experiment were to measure the effects of synchronising hourly energy and N release in the rumen in diets with two rates of energy release on growth, aspects of whole body metabolism and carcass traits in male lambs.

In a number of studies with beef cattle, diets composed mainly or entirely of grass silage have sustained lower growth rates and have resulted in a greater proportion of fat in the gain than high-concentrate diets offered at the same level of energy intake. However these have involved replacement of silage by concentrates in the diet and there would appear to be no comparative information on responses to adding silage or concentrates to a mixed diet. It is also not clear to what extent the lower growth rates sustained by silage are due to the higher energy content of the gain in animals given silage or to lower efficiency of utilization of metabolisable energy. A comparative slaughter experiment has been carried out to examine responses to the addition of silage or concentrates to the diet of lambs.

The metabolisable energy (ME) requirement for maintenance (MEm) can be determined by measuring the fasting metabolism of the non-lactating cow, but this approach cannot encompass any differences in maintenance metabolic rate between lactating and non-lactating animals. The MEm and efficiency of ME use for lactation (k1) can also be estimated by regression of energy outputs against ME intake (MEI). During 1992 to 1995, a total of 221 Holstein/Friesian lactating dairy cows, which were offered grass silage-based diets, were subjected to gaseous exchange measurements in indirect open-circuit respiration calorimeters. The objective of the present study was to use these data to predict the MEm and k1 by a range of regression techniques for lactating dairy cows offered grass silage-based diets.

The quality of protein supplied from grass silage is poor in relation to it's ability to sustain satisfactory levels of milk production and it is therefore necessary to use protein supplements in order to increase protein supply. However responses at the highest level of inclusion can be marginal with excess nitrogen being excreted and causing an increased environmental threat. The aim of this experiment was to examine the effect of six different concentrates fed in conjunction with grass silage, supplying two levels of dietary crude protein (CP) at three levels of degradability, on nitrogen partitioning by lactating cows.

The aims of this study were (i) to consider the information about cows that may be available for use on commercial farms and which may be useful in predicting intake and (ii) to quantify the variation that will exist between cows even when all of the available information has been used. This information is of fundamental importance to the development of rapidly applicable systems for predicting the intake of dairy cows.

The accurate prediction of the food intake of cows is a necessary step in the formulation of dairy rations because the formulation to meet requirements will depend on the level of intake. Intake may change as lactation progresses. The way in which intake changes with stage of lactation on foods of different composition is therefore central to intake prediction systems. However, in the vast majority of existing experiments, the influence of stage of lactation on intake is confounded with changes in either the allocation of the ration or the composition of the diet. The results reported here are from the first part of an experiment which was carried out to provide, for the first time, intake data for dairy cows throughout lactation where diet composition remains constant.

Previous experiments in this series showed that a major cause of the disappointing milk yield response to the partial replacement of grass silage by urea-treated whole crop wheat (WCW) was the low digestibility of the WCW. The present experiment was designed to investigate the effectiveness of various treatments in improving milk production from such diets. Treatments examined included pre-treatment of the WCW to improve digestibility, replacing part of the concentrates by molasses or ground wheat to increase rumen ammonia utilisation, and increasing the digestible undegradable protein (DUP) content of the concentrates.

Results from a previous study at this Institute indicated that concentrate energy source did not alter silage intake or animal performance of lactating dairy cows offered a range of grass silages of similar digestibility but differing in intake characteristics. Digestibility is probably the single most important variable affecting animal performance from grass silage. The present study was undertaken to examine the effects of concentrate energy source and effective rumen degradable protein (eRDP):digestible undegradable protein (DUP) ratio in the concentrate on the silage intake of, and animal performance from, lactating dairy cows offered a diverse range of grass silages differing in digestibility and intake characteristics.

Rumen inert fats are often included in dairy rations to increase the metabolisable energy (ME) supply whilst maintaining rumen function. Protected fat supplements have been shown to increase milk yields and fat content but with an associated and undesirable reduction in protein content. A reduced intake of rumen available energy (FME) may limit the microbial protein yield and so reduce the supply of amino acids to the mammary gland. Lactose supplements have been shown to increase the flow of microbial protein to the intestines (Chamberlain et al, 1993) and to reduce the effect of protected fats on milk protein content during early lactation (Garnsworthy, 1996). A trial was conducted to determine whether lactose supplementation could reduce the effects of protected fats on milk protein content during mid lactation.

It is estimated that ammonia emission from pigs contributes approximately 23kt of a total of 198kt from UK agriculture. Of this, 14kt is lost from buildings and 7.5kt from land spreading. It is likely that pig enterprises will need to reduce ammonia losses under the newly adopted Integrated Pollution Prevention Control (IPPC) legislation. Earlier work (Kay and Lee, 1996) has demonstrated that low crude protein (CP) diets reduce the amount of nitrogen in slurry. However, there is no information available on the effects of reducing nitrogen excretion by pigs on the emission of ammonia from buildings and limited information on the effects of collection and storage of slurry over time. The objective of this experiment was to determine the effect of low CP diets on the emission of ammonia from buildings, and on the characteristics of slurry collected and stored beneath slats.

Selection for carcass leanness in pig breeding schemes has promoted lean tissue growth rate whilst reducing body fat stores and appetite. Dietary protein restriction has been proposed as a way to enhance body fat reserves in the breeding animal. However, protein restriction during gilt rearing has been shown to adversely affect reproductive performance (Cia et al., 1996). The aim of this study was to test the effect of short term elevation of dietary protein prior to ovulation in gilts reared on restricted protein, to determine whether short term improvement in metabolic state could reverse these detrimental effects.

Commercially, restricting dietary nitrogen intake in breeding sows of lean genotype may be desirable. Reducing protein intake whilst maintaining high energy levels will result in limited lean tissue growth and promote fat accretion. This would be beneficial in ensuring more back fat reserves for lactation and reducing nitrogen pollution of the environment. However lowered protein levels during lactation have been shown to result in a negative nitrogen balance and extended weaning to oestrus intervals (King and Williams, 1984). In this experiment trans-rectal ultrasonography was used to assess any detrimental effects of protein restriction on ovarian activity in non lactating sows.

Feeding regimes in commercial practice do not always meet precisely the changing nutritional requirements of growing pigs. Increasing the number of feeds offered (phase feeding) or, alternatively, allowing the animals to select their own diet from a choice of foods may improve the balance between nutrient supply and animal requirements. The aim of this experiment was to compare 8 feeding strategies from weaning to slaughter at 90kg.

Both road type and journey time may influence the welfare of animals during road transportation. Animals may face a higher risk of injury on narrow, winding roads (Waran et al., 1993), and increasing the journey time may have deleterious consequences for animal welfare (Mormede et al., 1982), carcass bruising (Yeh et al., 1978), and meat quality (Wythes et al., 1981). In this study, the effects of road type and journey time on the behavioural and physiological responses of farmed red deer were investigated.

The farming of red deer (Cervus elaphus) for venison is a small but established part of the UK livestock industry. While slaughtering of deer is undertaken in commercial abattoirs, as yet there are no specific regulations governing the welfare of deer at this time. The behavioural characteristics of deer lead to the supposition that inappropriate pre-slaughter handling may adversely affect their welfare. In particular, exposure to unfamiliar species, as could occur in a multi-species abattoir, may be an area of particular concern: placing groups of unfamiliar animals next to each other has been reported to cause stress in cattle (Duchesne & Perry, 1975). Results of an experiment which investigated the location, orientation and behaviour of deer when penned between pens of unfamiliar species (i.e. modified preference testing) are presented.

Consumer demand theory has been used to assess the environmental requirements of domestic animals, because they will defend consumption of important resources, but not consumption of less important resources as their cost is increased (Dawkins, 1983). A commonly used approach is to place the cost on access to the resource, where once the animal has overcome the cost of access, there is no limit on time spent with a resource. So animals can compensate for fewer visits by spending longer with the resource on each visit (Sherwin and Nicol, 1995, Cooper and Mason, in press), in which case price paid and amount consumed may not covary, which would contravene the assumptions underlying the construction of demand functions (Mason et al., in press). In this experiment we investigated one solution to this problem: increasing the entry fee until the subject ceases to gain access to each resource.

Human intervention and selection of sheep for production characteristics have led to the establishment of defined breeds adapted to live in diverse environmental conditions. It is also apparent that the social and foraging behaviour of different breeds can vary considerably (Arnold, 1985; Dwyer and Lawrence, 1996), even within the same environment, and variations in social behaviour may have significant effects on production (Lawrence and Wood-Gush, 1988). It remains to be established, however, whether these behavioural differences have a genetic basis, or result from the cultural transmission of information and learned behaviour. The aim of this study was to examine the effects of ewe genotype and behaviour on the behaviour of lambs of different breeds derived by embryo-transfer.

One of the major limitations to increasing the polyunsaturated fatty acid (FA) composition of ruminant products is the fact that these FAs tend to get hydrogenated by rumen micro-organisms to more saturated end products (biohydrogenation). This experiment reports on the extent of FA biohydrogenation in the rumen of four diets of differing sources of long chain polyunsaturated FA (PUFA) as used by Scollan et al. (1997).

Concerns regarding levels of fat consumption and particularly saturated fatty acids (FA) (Department of Health, 1994), has resulted in closer scrutiny of the FA composition of ruminant products. The FAs deposited in beef tissues are relatively saturated, leading to a low polyunsaturated:saturated FA ratio (P:S) in the meat (approximately 0.1, the ideal being about 0.4), whilst the n-6:n-3 ratio is beneficially low at approximately 2. Feeding strategies for raising the P:S ratio whilst keeping n-6:n-3 ratio low are required. This experiment has investigated the impact of feeding different sources of long chain polyunsaturated FA (PUFA) on animal performance and the FA composition of muscle.