Accurate prediction of daily food intake is a fundamental pre-requisite of any nutritional model designed to provide feeding recommendations for lactating dairy cattle. From an evaluation of five of the most commonly used models to predict food intake, Keady et al. (2001) observed a considerable range of accuracy of prediction, with some under-predicting intake by 0.9 kg DM/cow/day, whilst others over-predicted intake by up to 2.9 kg DM/cow/day. The aim of the current study was to develop a model, encompassing both animal and feed variables, which accurately predicts food intake of lactating dairy cattle offered a range of diets in production systems currently employed on dairy farms. The new model has been adopted to predict food intake in the Feed into Milk (FIM) rationing system.

One of the cornerstones in the development of a new feed rationing system for dairy cows must involve a reappraisal of both the concepts and ‘numbers’ adopted in defining the energy requirements for dairy cows. This is particularly important in the present scenario where increasingly high levels of animal output are being achieved from very different animal genotypes to those used in UK dairying 20 - 30 years ago. One of the tasks within the Feed Into Milk (FIM) project was to develop a new system to predict the energy requirements of todays dairy cow. The objective of the present study was to collate all available energy metabolism data with dairy cows in the UK and to develop relationships for describing metabolisable energy (ME) requirement for maintenance (MEm) and efficiency of ME use for lactation (kl) using both existing and new methodologies.

The Feed into Milk (FIM) project in the United Kingdom has developed a Mitscherlich equation from calorimetric data for energy rationing of dairy cattle (Agnew et al., 2004). The objective of the present study was to evaluate this equation using independent data sets obtained in both calorimetric and production studies.

Under Northern Ireland conditions, Keady et al. (2002, 2003) obtained positive responses in milk production to the inclusion of maize silage in grass silage-based diets. However, while the area of forage maize is increasing, there is considerable interest in the production of whole crop wheat as a forage for feeding to lactating dairy cows. The objective of the study was to examine the responses of lactating dairy cows to the inclusion of maize silage or fermented whole crop wheat silage in grass silage-based diets. Furthermore, the concentrate sparing effects of maize and wheat silage were determined. Finally the effect of protein level in the concentrate supplement when offered with the different forages, was evaluated.

As a consequence of the anticipated ban on all in-feed antibiotics in the European Union, novel alternatives are being intensively investigated in the adult ruminant area. Previous reports have documented the potential of natural plant extracts and their principle components to modify rumen dynamics in vitro (Evans and Martin, 2000; Wallace et al., 2002). However, more data needs to be accumulated on the underlying mechanism of action of these phytocompounds on the rumen microflora. The aim of this study is to use molecular methods in order to elucidate the effects of two plant extracts, namely cinnamaldehyde and garlic extract in comparison to the ionophore antibiotic monensin on the structure of the microbial community in a rumen-simulating dual flow continuous culture system.

Ruminants grazing on forages that contain condensed tannins (CT) have lower parasite burdens compared to those grazing on similar quality, tannin-free forages (Min and Hart, 2003). Evidence from previous grazing studies suggested that chicory, which contains only traces of CT, could also reduce the size of the parasite population carried by ruminants (Hoskin et al. 1999). Such bioactive plants may have direct anthelminthic effect on different developmental stages of the worms or indirect effects through nutritional improvement of host immunity. The purpose of this study was to determine whether short-term grazing of bioactive forages could affect either the established adult population or incoming infective larvae of Teladorsagia circumcincta a common abomasal parasite of sheep. The bioactive species tested were chicory (Chicorium intybus) and the CT-containing plants: lotus (Lotus pedunculatus), sainfoin (Onobrychis viciifolia) and sulla (Hedysarum coronarium).

It has been suggested that the periparturient breakdown of immunity to parasites has a nutritional basis (Coop and Kyriazakis, 1999). The often observed breakdown of immunity to abomasal nematodes in lactating sheep is indeed sensitive to metabolizable protein (MP) scarcity (Houdijk et al., 2003). However, a periparturient breakdown of immunity to intestinal nematodes is less likely to occur (Jackson et al., 1988). This discrepancy suggests that immunity to abomasal and intestinal nematodes may differ in their sensitivity to changes in MP supply. The objective of this experiment was to assess whether immunity to intestinal nematodes in lactating sheep is sensitive to MP supply.

A hypothesis for the role of improved ewe nutrition, notably protein, in reducing the peri-parturient rise (PPR) in nematode faecal egg output has been developed by Coop and Kyriazakis (1999). More recently this hypothesis has been tested in field studies with organically managed ewes (Keatinge et al, 2003). It might also be expected that maternal body reserves could affect the potential availability of nutrients for further metabolism by the host animal. The objective of this experiment was to assess the effect of ewe body condition at lambing, on animal performance parametres and the PPR in ewe faecal egg output.

There is an increasing body of evidence to support the view that the periparturient breakdown of immunity to parasites has a nutritional basis; an increased supply of metabolizable protein (MP), at times of MP scarcity, would reduce abomasal nematode egg excretion and worm burdens in periparturient ewes (Houdijk et al., 2001). It has been suggested that an increased MP supply may rapidly improve expression of immunity to gastrointestinal nematodes; immunity improved within one week when the MP demand of lactating ewes was reduced, at times of MP scarcity (Houdijk et al., 2003). Here, it was assessed if changes in MP supply can result in similarly rapid changes.

Increased anthelmintic resistance worldwide has lead many to investigate alternative methods of parasite control (Donaldson et al. 1998). In sheep it is believed that the larval contamination of the pasture is derived mainly from the mature breeding ewe due to the periparturient relaxation of immunity (PPRI). Donaldson et al. (1998) reported that increasing the metabolisable protein (MP) supply of the ewe in late pregnancy may moderate the PPRI. Previous studies investigating the effect of MP supply to dairy ewes on faecal nematode egg output have, however, not shown significant differences (Partington et al. 2003). This study investigates the effects of both MP supply and the effect of milking on the PPRI and worm burden.

The use of direct fed microbials has been shown to enhance digestion in the ruminant. One source of microbial live populations is a yeast culture Saccharomyces cerevisae (Yea-Sacc1026, CBS 493.94; Alltech Inc, USA), and its use in ruminants has been associated with a range of benefits including an overall increase in dry matter and fiber digestibility (Wiedmeier and Arambel, 1985), combating heat stress in lactating cows (Huber and Higgenbotham, 1985) and increased performance (Fallon and Harte, 1987). Glade and Biesik (1982) working with yearling horses, demonstrated increased DM and N digestibility when S. cerevisae was added to the diet. It was suggested that S. cerevisae enhanced cellulolytic activity, triggering microbial metabolism changes in the horse’s large intestine that enhance hemicellulose fermentation. They also reported that the addition of S. cerevisae results in smaller percentages of absorbed nitrogen excreted in the urine, indicating that the biological value of the S. cerevisae -supplemented diets may be more than the direct contribution of the nitrogen within the yeast itself. The aim of this review is to determine the effects of S. cerevisae on performance parameters of bulls.

The production of early-weaned lamb is a high cost production system with the major cost being the concentrate consumed by the lamb. However the transformation of concentrate to weight gain is more efficient when the concentrate is fed to the lamb directly rather than fed to the dam and the lamb avails of the mother’s milk. This type of finishing system requires a lamb with a high lean proportion in the carcass, a trait that characterises Texel cross lambs. Molasses, a by-product of the sugar processing industry, is high in soluble carbohydrates and is a common ingredient in commercial animal feed formulations. Inclusion levels in excess of 10% have been reported to cause excessive stickiness of the feed (Ewing, 1997). Molasses based diets increase propionic acid concentrations in sheep (Cortez et al., 1987), which promotes soft carcass fat (Bozzolo et al., 1990). The objective of this experiment was to determine the optimum inclusion rate of molasses in the diet of early-weaned lambs, based on growth rate, lamb cleanliness and carcass characteristics.

A significant fraction (≈ 50%) of methionine (Met) in the diet of weaned pigs is retained by the portal drained viscera (Stoll, et al. 1998). The consequent reduction in extraintestinal availability of Met may compromise piglet performance. Met regeneration in hepatic and renal tissues is achieved through combination of a methyl group from either N5-methyl-tetrahydrafolate or from betaine (trimethyl-glycine) with the Met derivative homocysteine. Supplementing the diet with betaine might therefore improve extraintestinal Met availability and piglet performance. Furthermore, betaine is an osmolyte and has been shown to stabilize or protect the intestinal epithelial structure of broilers under conditions of intestinal stress (Kettunen, et al. 2001). Provision of supplementary betaine in the diet of the newly weaned pig may thus reduce the extent of small intestine (SI) morphological degeneration characteristic of the early post-weaning period. The study reported here was designed to test these hypotheses.

As pigs mature their requirements for amino acids decline. Phase feeding a series of diets of reducing protein and amino acid content has the potential to increase growth rate and improve feed conversion efficiency because less surplus nitrogen (N) is excreted. In addition, phase feeding is expected to reduce the amount of N excreted in the manure. This experiment was carried out to assess the response of group penned growing-finishing pigs to feeding a single diet throughout or a sequence of five diets of high, medium or low amino acid content.

Cereals have traditionally been used in the pig industry as the main source of energy in pig diets. However, as a result of cereal availability and price, alternative sources of energy have been considered, for example the addition of oil to cereal by-product-based diets. By-product-based diets commonly contain higher levels of fibre than cereal-based diets and several studies (e.g. Bakker et al 1995) have reported them to be less digestible in terms of dry matter (DM), energy, crude protein (CP) and oil. The lower DM digestibility of by-product-based diets may lead to a higher level of slurry output, which is an increasing environmental concern. The aim of this work was to examine the differences in digestibility between by-product-based diets supplemented with oil and cereal-based diets.

The post-weaning growth check causes considerable economic losses in pig production. Some of the problems in susceptibility to disease have been associated with immunoregulation. For example, immaturity of the neonatal immune system, stress-associated and pathogen-induced immunosuppression have all been linked to increased disease susceptibility throughout the early post-weaning period. Studies in both infants and animal models suggest that dietary nucleotides have significant effects on the immune and gastrointestinal systems (see Carver, 1999). It has been suggested that under conditions of limited nucleotide intake, rapid growth or certain disease challenges, dietary (or preformed) nucleotides may spare the cost of de novo nucleotide synthesis and optimise the metabolic function of rapidly dividing tissues such as those of the gastrointestinal and immune systems. The aims of the current study were to determine the effects of a yeast-based nucleotide source (Ascogen™; Chemoforma Ltd, Switzerland) on performance, gut physiology, microflora and immunological parameters in post-weaned piglets.

The exposure of pigs to different pathogens compromises productivity (Greiner et al., 2000), i.e. reduces weight gain and food intake, even in the absence of clinical disease. Associations between productivity and a range of immunological traits have been demonstrated in apparently healthy animals facing the same infectious challenge (Clapperton et al., 2003). Specifically, it was demonstrated that some leucocyte proportions (monocytes, B cells, MIL-4 (NK) positive cells) increased significantly as performance decreased. This study aims to verify these previous results on an independent population of pigs, examine relationships between immune measures and actual bacterial counts in the gut, and examine the influence of diet type on these measurements.

The performance of commercial pigs is often below that seen under good experimental conditions. At least some of this decrease in performance can be attributed to environmental stressors. Stressors in the physical environment have been modelled (e.g., Black et al., 1986) allowing predictions of performance under varying conditions to be made. However, the influence of social stressors, including group size (N), space allowance (SPA, m2/BW0.67), feeder space allowance (FSA, feeder spaces/pig), and mixing, on pig performance, although undeniable, is generally ignored in pig growth modelling. The aim here was to quantify the effects of the major social stressors on the performance of growing pigs. Genetic variation in the ability to cope, and the social stressor effects were integrated to produce a more general growth model.

Models intended to simulate animal performance typically represent a single animal. The assumption necessarily made is that the response of the population will be the same as that of the deterministically simulated response of the ‘average’ individual. However, this will necessarily be the case only if all animals in the population have an equal growth potential, all are at the same stage of growth and all react in the same way to encountered stressors. In order to predict adequately the response of a population in a given environment it is necessary to take account of between animal variation. The objective of this work was to investigate the impact of between-animal variation on the predicted performance of a population of growing pigs.