In the absence of sufficient energy from a carbohydrate source, the GIT microflora can also use protein as a source of energy, by splitting amino acids leading to the formation of volatile fatty acids and ammonia (NH3). Therefore, it is hypothesized that the addition of fermentable carbohydrates to an animal diet, could reduce the concentration of NH3 of the gastro-intestinal tract (GIT) digesta, particularly in relation to the area where the fermentation takes place.

Nutrition models of energy and protein utilisation have been developed for lactating pigs but there is little or no evidence in the scientific literature of the validation of such models. If there are systematic discrepancies in such models, then inappropriate supply of nutrients will either be an inefficient use of resources with oversupply or have an impact on piglet growth and subsequent reproductive performance of the sow with undersupply. In the current study, lactating gilts were fed isoenergetic diets differing in ileal digestible lysine: energy. Protein and energy utilisation were predicted using existing nutrition equations. The validity of the energy and protein utilisation equations was tested by determining if the predicted energy balance differed significantly from zero or if the predicted protein balance was not significantly less than zero.

Gastrointestinal infection caused by pathogenic bacteria and viruses are an important cause of diarrhoea and ill-thrift in human and animal neonates (Guerrant et al., 1986, Radostits et al., 1994). Escherichia coli (E.coli) and Rotavirus are both important causes of neonatal diarrhoea, in addition E.coli is an important factor in the post-weaning diarrhoea syndrome seen in early weaned piglets (Radostits et al., 1994). Neonates reared on maternal milk are protected by antibodies (IgA in humans and pigs, IgG in ruminants) which act passively in the gut against organisms which cause gastrointestinal disease. This study investigated the protective effect of egg antibodies (Lohmann Animal Health) against E.coli and Rotavirus challenge in neonatal piglets. The eggs were sourced from hens vaccinated against E.coli and Rotavirus.

Respiratory health is an important aspect of pig production due to its effects on pig performance and welfare. Haptoglobin, an acute phase protein, has been identified as a sensitive indicator of infection with respiratory pathogens such as Actinobacillus pleuropneumoniae and has been suggested as a possible marker for non-specific surveillance of pig health status (Heergaard et al., 1998). Other acute phase proteins such as Major Acute Phase protein (MAP) and Serum Amyloid A (SAA) may also be of use in disease surveillance. However, little is known about the variation of these proteins and their associations with post-mortem signs of disease in the pig. This information could be of importance in monitoring herd health and in facilitating ante- and post-mortem inspection by identifying diseased animals. This study was designed to determine whether various acute phase proteins could be used to identify enzootic or pleuropneumonia in individual pigs or farms with increased prevalence of these diseases.

Insulin-like growth factor-1 has been positively associated components of growth in pigs, such as protein deposition. Therefore, serum insulin-like growth factor-1 concentration (IGF-1) was measured in lines of pigs divergently selected for daily food intake (DFI) or for efficient lean growth rate (LGS) to determine if there was a non-zero genetic association between IGF-1 and the selection criteria. If a genetic association did exist, then IGF-1 could be used as a physiological predictor of genetic merit in a breeding programme. The presence of a major gene effect on IGF-1 was also examined in the study.

A non-invasive method is proposed for determining the extent of degradation in the rumen, based on the gas production technique and mathematical modelling. The exercise involves developing both a statistical model and a kinetic model (France et al., 2000). The statistical model shifts (or maps) the gas accumulation profile obtained using a faecal inoculum to a rumen gas profile, thus obviating the need for rumen sampling. The kinetic model determines the extent of degradation in the rumen from the shifted profile. It is presented as a generalised mathematical function, allowing any one of a number of alternative equation forms to be selected.

Previous attempts (Offer & Percival, 1998) have been made to develop a prediction system for rumen fermentation patterns from stepwise multiple linear regressions of the chemical constituents of the diet. These authors have also made comparisons between equations derived from diet wet chemistry and those developed from near infrared reflectance spectroscopy (NIRS). However, the potential of NIRS to predict the dynamics of rumen fermentation has not fully been explored using a wide range of forage treatments. Therefore the objective of this experiment was to develop equations from the chemical composition of the diet to predict rumen fermentation patterns and compare these with equations developed from undried and dried NIRS scans of the diets.

Peptides and to a lesser extent amino acids accumulate in rumen fluid in the early post feeding period and rapidly decline thereafter (Broderick & Wallace, 1988). Numerous studies have demonstrated benefits to feeding peptides, in terms of increased microbial growth in the rumen (Newbold, 1999). However, given that peptides will only be available in the rumen for a short time after feeding it may be necessary to match supply of peptides and energy in the rumen to maximise the stimulation in microbial activity. The objective of this study was thus to investigate if microbial protein synthesis in rumen fluid would be enhanced by a synchronous provision of peptides and energy.

Novel lines of high sugar ryegrass have been shown to increase the efficiency of N use and milk production in zero-grazed cattle (Miller et al., 1999). An experiment was carried out to determine whether this was in part due to an increase in the efficiency of microbial protein synthesis in response to the amount and availability of water soluble carbohydrate (WSC) increasing the balance between energy and nitrogen supply to the rumen microbial population.

The poor efficiency with which ruminants utilise nitrogen (N) for growth may be due to differences in the temporal pattern of energy and protein absorption following a meal. Efficiency is higher in non ruminant animals where energy (glucose) and protein is absorbed from the same site and at the same time following a meal. Indeed, when an asynchronous pattern of energy and protein supply is imposed on non ruminants, the efficiency of nitrogen utilisation is reduced (Barja et al., 1972). The present experiment compares the efficiency of N utilisation in growing lambs given different temporal patterns of post-ruminal energy and protein supply.

Forage based feeding systems are often disadvantaged compared with those based on high cereal usage in terms of feed intake, live weight gain and efficiency of utilisation of dietary energy and protein. Furthermore, under some situations, particularly with animals fed on grass silage, cattle often have higher fat:protein carcass ratios than those fed other forage-diets. However, other factors such as age, genotype and physiological state may also influence nutrient partitioning. An experiment was conducted to investigate the effect of diet (based on silage alone or supplemented with additional energy and/or protein) and stage of development on the partitioning of nutrients between fat and lean deposition. Overall effects of diet on animal performance and carcass composition were reported by Scollan et al. (1999).

Piglets commonly show a setback in growth and a low intake of solid feed on weaning at three to four weeks of age. Outdoor reared piglets, however, have been found to spend more time eating solid feed than indoor reared piglets in straw yard weaning pens (Webster and Dawkins 2000, Cox and Cooper 2001), even though outdoor piglets do not conventionally receive creep feed prior to weaning. Outdoor piglets are, furthermore, frequently observed chewing the roll nuts provided to outdoor sows. In this study, therefore, we investigated the effect of two aspects of outdoor rearing on the feeding behaviour of indoor reared piglets. These aspects were maternal facilitation of feeding and large pellet size.

The objective of this experiment was to provide a severe test of the two frameworks currently available for understanding and predicting voluntary food intake. Framework 1 predicts that an animal will eat at a level that will allow potential performance to be achieved subject to its capacity to deal with a constraint, such as the bulk content of the food, not being exceeded. In framework 2 intake is seen as that which will allow some biological efficiency, such as the ratio of net energy intake per litre of oxygen consumed, to be maximised (Tolkamp and Ketelaars, 1992). The frameworks differ in their prediction of the effect that a period of prior feeding on a high bulk food (severely limiting) will have upon the subsequent intake of foods of differing bulk content. Framework 1 predicts that the intake of a low bulk food, that is non limiting, but not that of a moderate bulk food, that is limiting, will be increased under such circumstances. Framework 2 predicts that intake will be increased regardless of the type of food being fed as long as the Metabolisable Energy of that food is utilised more efficiently.

The provision of creep feed to suckling pigs is considered to stimulate early food intake as well as health post weaning. However, Barnett et al. (1989) found no effects of creep feeding on post-weaning performance. Research by Pajor et al. (1986) indicated that there is a high variability in creep feed intake both among and within litters. This variability in creep feed intake is probably the main cause of disagreement on the effects of creep feed provision. The objective of the present study was to assess the effect of creep feed consumption on individual food intake characteristics and performance of group-housed weaned pigs. Chromic oxide was added to the creep feed to identify piglets that consumed food during the suckling period. In the piggery, IVOG®-feeding stations were used to measure individual food intake after weaning.

Characteristically, voluntary food intake in the young pig in the days after weaning is low and very variable. Such low feed intakes can lead to reduced digestive efficiency and ultimately poorer physical performance. This is due to the digestive tract requiring a continuous supply of nutrients to maintain gut integrity and digestive capacity.

The presence of this check in a young pigs growth immediately after weaning is a well documented problem of commercial significance. It is multi faceted and has been found to encompass many issues such as stocking density, mixing of litters, feeder type and space and the formulation and presentation of the feed.

The Braude scholarship enabled me to travel across Europe to visit various research institutes and commercial companies in the Netherlands, Belgium and Poland including, ID-Lelystad, Institute for Animal Health, Netherlands, Rosmalen Institute for Pig Research, Netherlands and the experimental farms of the Provimi Group in Veldriel, Netherlands and Central Soya, Chelmno, Poland who were all engaged in trying to find solutions to the postweaning problem. The research they were involved in was as diverse as the problem itself appears to be.

Selection for milk production alone would lead to a genetic decline in cow fertility (e.g. Kadarmideen et al., 2000) thus incorporation of fertility in selection seems desirable. The Dairy Information System (DAISY) is a comprehensive recording scheme for insemination and health events and hence the data quality is more reliable for genetic analysis of cow fertility. The objective of this study was to analyse DAISY data to estimate sire breeding values and genetic parameters for various fertility measures based on insemination and calving events on daughters.

Increasing genetic merit for production has been associated with a decline in dairy cow fertility. In order to sustain lactation it appears that appreciable amounts of body condition are being mobilised, which may impinge on fertility. Body condition score (BCS) of first lactation heifers is recorded by Holstein UK and Ireland (HUKI) as part of its national type classification scheme. BCS may be a useful selection criterion for improving fertility. Calving dates and hence calving interval (CI) are generally very reliably recorded, but the usefulness of CI as a selection criterion is hampered for a number of reasons, one being that only the most fertile cows have two consecutive calving dates. This is a serious issue that still needs to be addressed. Our aim here was to investigate if there is genetic covariation between BCS and CI after adjustment for milk yield and to investigate selection responses in all three traits when selection is for each trait in turn and how responses are affected by restrictions imposing no genetic change in one of the traits. Restricting a trait to no change when it is correlated to a trait under selection may be important in developing customised indexes to satisfy specific requirements.

Breeding programmes for Holstein Friesian (HF) animals have been based on improved milk production with little emphasis on functional traits such as fertility. This has resulted in a rapid increase in milk production potential of the national dairy herd but unfortunately this has been at the expense of issues such as longevity, especially due to poor reproductive performance. In contrast Norwegian (NC) dairy cattle have been bred via a multi-trait selection procedure for 25 years and there is evidence that fertility has improved during that period. These differences in selection procedures for the two breeds may have major effects on overall herd output and profitability within the grass-based systems of milk production employed in Northern Ireland. The present study is part of an overall study comparing the effects of HF and NC genotypes on food intake, animal performance, nutrient utilisation, behaviour, health, fertility and longevity. The objective of the present paper is to present the effects of breed on food intake and utilisation, and animal performance when offered two levels of nutrient inputs based on grass silage-based diets.

The term ‘negative energy balance’ (NEB) is used to describe the condition in early lactation when the energy available from food intake is lower than that of the energy used by the cow for milk output, maintenance and activity. Current selection objectives may be favouring cows that are genetically predisposed to mobilise body tissue. This may have consequences for fertility since cows appear to resume reproductive activity only after the nadir of NEB has passed (Veerkamp et al., 2000). Extreme NEB may be considered generally undesirable, as it is a precursor to health and fertility problems. The aims of this study were: 1) to predict genetic merit for sires for traits contributing to energy balance; 2) to combine those breeding values into an overall energy balance evaluation for bulls using either daily energy flux or body state changes.

Profitability of hill sheep enterprises depends on both maternal and lamb traits, and selection programmes should include all aspects of performance. However, the relative contribution of different traits to overall profitability depends on the type of hill farm and, specifically, the severity of the environmental constraints on the farm (Conington et al., 2000). The objective of this paper is to derive and evaluate selection indexes for holistic and sustainable genetic improvement of hill sheep on ‘intensive’ and ‘extensive’ hill farms by considering carcass, maternal and ‘sustainability’ traits simultaneously.