Newly weaned pigs are at least partially protected against sub-clinical gastrointestinal disorders through the provision of in-feed antimicrobials. Possible associations with antibiotic resistance to life threatening bacterial infections in humans and environmental pollution will result in their ban. As a consequence, gut health and pig performance will be compromised. Current research is aimed at reducing, and eventually overcoming, such consequences through novel nutritional strategies. Effects of the latter on the consequences of sub-clinical infection may be assessed in an infection model, since the absence of in-feed antimicrobials does not always lead to gastrointestinal disorders, due to e.g. variation in infectious environmental conditions. A common gastrointestinal disorder is post-weaning colibacillosis (PWC), which is caused by enterotoxigenic E. coli (ETEC), and is associated with diarrhoea and reduced food intake, and hence reduced performance. Existing ETEC infection models, which have yielded variable results and employed relatively large infective doses of ETEC, have focused on clinical PWC (Madec et al., 2000). The objective of our experiment was to assess whether sub-clinical PWC can be induced through experimental infection with ETEC, and whether such sub-clinical PWC is sensitive to the level of infection used.

Development of early maturing forage maize varieties has enabled the crop to be grown in more marginal areas of the UK, consequently the crop is harvested at a range of maturities and dry matter (DM) concentrations. Digestibility of maize silage DM is reported to remain relatively constant over a wide range of maturities; however very mature maize is known to suffer reduced DM digestibility (Bal, Coors and Shaver, 1997). The objective of this experiment was to measure nutrient digestibility of maize silage harvested at stages of maturity commonly experienced in the UK.

Microbial protein is the most variable and uncertain element of current systems of evaluating protein requirements for ruminants. The variability is partly a result of the multiplicity of techniques used to quantify microbial nitrogen (MN) yield and partly due to unrepresentative sampling of microbial cells. In a number of studies in the literature it is tacitly assumed that marker:N ratios in rumen liquid associated bacteria (LAB), solid associated bacteria (SAB) and duodenal digesta bacteria (DDB) are identical. Under ordinary feeding conditions ruminal SAB are numerically predominant and may comprise 50-75% of the total microbiota (Mitsumori and Minato, 1997). This study highlights the variations in chemical composition in LAB, SAB and DDB and their implications in estimating microbial growth. The study also simultaneously compares four microbial markers in vivo.

Ordinary least squares (OLS) regression will give negatively biased estimates of slope if the x-variable is subject to measurement errors. In energy balance regression, metabolisable energy intake (MEI) is neither under precise control nor free from measurement errors. In order to improve the accuracy of prediction of energy requirements, it is necessary to recognise the effect of this bias when deriving estimates of maintenance (M) energy requirements and the efficiency of utilisation of energy for growth (kf).

High-yielding dairy cows must produce large amounts of milk of a desired quality from a cost-effective diet in order for the farmer to remain in profit. Optimal rumen function and health is a key part of the process of converting nutrients into milk efficiently. Essential oils are steam-volatile or organic-solvent extracts of plants that have been shown to have beneficial effects on human digestion. They are mainly cyclic hydrocarbons and their alcohol, aldehyde or ester derivatives (Wallace, 2004). ‘Crina Ruminants’ is a blend of such essential oil compounds, designed to stimulate rumen activity and boost the population of beneficial microbes, through anti-microbial and digestive stimulant activity. In particular, it is believed to encourage an increase in fibre-fermenting bacteria and to counteract the acidotic rumen conditions that can be caused by feeding high starch diets. The aim of this experiment was to evaluate the effects of ‘Crina Ruminants’ on intake and milk production.

In classical quantitative genetic models, phenotypic value depends on genotype, but phenotypic variation among individuals of the same genotype is assumed to be the same for all genotypes. ANOVA and other statistical tests are underpinned by the assumption of a multivariate normal distribution with homogenous variances and independent normally distributed deviations. Heterogeneity of phenotypic or environmental variance has been estimated in dairy cattle (Brotherstone and Hill, 1986). Models and analyses developed by SanChristobal et al. (1998) and Sorenson and Waagepeterson (2003) provide strong evidence for litter size in pigs of heterogeneity of residual variance under genetic control. Environmental sensitivity dependent upon genotype has implications for livestock production, and may explain phenomena such as plasticity and canalisation. The aim was to calculate variability in within family variance among large half sib broiler families, in order to test for the presence of and quantify heterogeneity in residual variation amongst genotypes.

Vegetable proteins, including soya-bean meal (SBM), can only be included in diets for newly-weaned piglets in restricted amounts as they can induce a transient local gut hypersensitivity. This hypersensitivity may be a causative factor in post-weaning diarrhoea. Previous studies have indicated a strong maternal influence on the response of piglets to SBM. The object of the current experiment was to assess more formally maternal influences on weaning performance of piglets

Fertility of UK dairy cows is at an all time low (Royal et al., 2000). Genetic improvements through direct selection is minimal since parameters can only be measured in the mature female and generally have low heritability (h2 < 0.1). It may be possible to overcome these genetic limitations with the use of an indirect selection criterion. Whilst commencement of luteal activity might prove a valuable genetic indicator of female fertility (Darwash et al., 1997), a major step forward would be the identification of a highly heritable trait in the male that is measurable in early life and genetically correlated to a measurement of female fertility. The physiological control of reproduction is by the same gonadotrophic hormones in both sexes (Land, 1973), and Haley et al. (1989) reported that the underlying variation in gonadotrophin response to GnRH is controlled by the same genes in both sexes. High heritabilities (0.4–0.55) for the response to GnRH have been reported in ram lambs (Haley et al., 1989) and beef bulls (Mackinnon et al., 1991). The objective of this study was to estimate the genetic variation in a number of parameters associated with the LH response to a GnRH challenge in pre-pubertal Holstein-Friesian (H/F) heifers.

An earlier study at Langhill (Veerkamp et al, 1995) showed that selection for yield in dairy cows increases body tissue mobilisation during lactation, since high genetic merit animals had a lower average condition score (CS) compared with low genetic merit animals. However, in this study no diet effect for condition score and no interaction between diet and genetic merit was found. The reasons for this might have been that average condition scores during lactation were analysed, and therefore the objective of this study was to evaluate the effects of genotype and diet during lactation using weekly observations.

Empty body (EB) weight (EBW) is used to estimate the energy and protein requirements for maintenance for dairy cattle. It is predicted from live weight (LW), but the prediction can be influenced by a number of factors, e.g., feed and water intake, pregnancy and body condition. The objective of the present study was to develop prediction equations for EBW and carcass weight in lactating dairy cows using LW and other live animal data.

Slaughter weight in UK pig production is increasing annually, with an associated increase in age at slaughter. This increases risk of reaching sexual maturity and a reduction in carcass quality and production efficiency. In entire boars, puberty is associated with increased aggression levels and the production of hormones causing carcass taint. Management systems and production practices may affect these risks. Thomas et al (1979) found that extensive housing and management systems increased the risk of pigs reaching puberty. In previous Scandinavian research, Fredriksen et al (2005) found that maintaining stable litter groups reduced aggression and mounting behaviour, and gave a lower propensity for carcass taint at slaughter. To date, there is a lack of research examining the effects of these factors on physiological development and aggression under UK conditions. This study explored the effect of stable litter grouping and housing system on performance, aggression and physiological maturity in entire males and gilts over the 60kg-130kg weight range.

There is a large body of research investigating the nutritional needs of the dog at different life-stages and the use of different feed ingredients in commercial diets (Clapper et al, 2001; Schroeder & Smith, 2008). Despite this, though there has been relatively little published work looking at the role the large intestine plays in nutrient digestion in the dog. The dog’s gastro-intestinal tract has been compared to the cat’s in terms of relative length. However the cat is a true carnivore and has little need to ferment fibre from the diet, whereas the dog is a scavenger and will consume a much wider range of food, and therefore may need to ferment fibrous material from the diet. The dog may therefore require a more developed large intestine to harbour a microbial population to aid in the digestion of this fibrous material. This study was performed to determine differences in digestion of nutrients in this segment of the canine gastrointestinal tract.

In tropical countries is a common practice to feed cattle with variety of forage trees as supplements. In order to develop adequate strategies for management of trees, an assessment is needed of their potential use (intake) by cattle. Little research has been conducted in this area, and most effort has been focused on single forage evaluation. The objective of this experiment was to assess the preference by cattle of five forage trees. Preference was taken as the voluntary intake of a tree forage offered in a cafeteria trial.

The existence of genotype by environment interaction (G*E) can cause a change in the ranking of bulls tested in one environment when their daughters are subsequently milked in another environment. If the degree of re-ranking is large, the genetic correlation between milk production in the two environments will be substantially less than 1.0, with the implication that proofs made in one environment may not be reliable predictors of proofs in the second environment. The aim of this study was to investigate the effect of increasing the difference between environments, defined on the basis of herd average milk yield, on the genetic correlation (rg) for milk, fat and protein yield in Holstein Friesian dairy cattle in Ireland.

In an extensive review of energy metabolism of dairy cows, Agnew and Yan (2000) concluded that high genetic merit cows are capable of partitioning more energy into milk and less into body tissue when compared to low genetic merit cows. The objective of the present study was to use production data for a complete lactation to evaluate the effect of cow genotype on energy partitioning between milk and body tissue.

Tail biting is a widespread adverse behaviour that occurs in growing pigs but, as of yet, no one knows what initially encourages the development of this behavioural problem. It has been suggested that tail biting is linked to a behavioural predisposition, exacerbated by environmental inadequacy, or a nutritional deficiency such as inadequate protein or minerals. Using a model tail test, Fraser (1987, 1991) demonstrated an experimental link between mineral or protein dietary deficiencies and an increased attraction to blood. Using this test, Fraser demonstrated that large individual variation exists between pigs in the extent of their attraction to blood. The current experiment extended this tail test to investigate the nature of the attraction to blood, and to examine factors that may be related to tail biting predisposition.

The gas production (GP) technique has been developed to assess dynamics of ruminant digestion. Relationships have been observed between a feed's GP profile and in vivo parameters such as digestibility (Khazaal et al., 1993), feed intake and growth rate (Blümmel and Ørskov, 1993), and in situ degradability (Sileshi et al., 1997). However, there are few studies which relate GP data to the in vivo pattern of rumen fermentation (in terms of the rate of pH decline 2 h post-feeding and the mean rumen pH, concentration of total VFA and molar proportion of individual VFA). The object of this experiment was to determine whether such a relationship existed between a feed's GP profile and the pattern of rumen fermentation observed in animals fed that feed.

Lipids are present in muscles as structural components of the muscle membranes, as storage droplets of triacylglycerol between muscle fibres and as adipose tissue (marbling fat). These lipids, or more precisely their fatty acids, contribute to a wide range of quality attributes. For fresh meat these are colour stability, drip loss and the development of oxidative rancidity. Meat colour and level of marbling are the two major factors relevant to the selection of meat by the consumer. Eating quality of meat is judged by texture and flavour. The former depends, in part, upon marbling fat which also contributes to juiciness, and flavour depends upon products from the thermal oxidation of lipids. These breakdown products react with other meat constituents to produce flavour and odour compounds. Finally, nutritional quality depends upon the fat content of the meat and it’s fatty acid composition.

There is evidence from UK field data to suggest that selection for milk yield has led to a deterioration in the fertility of lactating dairy cows (Pryce et al., 1997). As cow fertility may be affected by metabolic load and lactation effects, it is important to investigate the fertility of non-lactating heifers. Since 1973 selection line (S) cows at the Langhill Dairy Cattle Research Centre have been bred to bulls with the highest predicted transmitting abilities for weights of fat plus protein (PTA F+P) available in the UK, while the control line (C) are of about UK average genetic merit for PTA F+P. Results using data from lactating Langhill cows show that S cows have calving intervals that are, on average, 12 days longer than C cows, which is a combination of poorer conception rates and a delay in first observed oestrus (Pryce et al., 1999). The objective of this study was to investigate the effect of selection for PTA F+P on the fertility of maiden heifers at Langhill.

In recent years there has been a shift in emphasis in livestock production away from increased muscle growth towards improved meat quality. The final eating quality of meat depends on a number of organoleptic properties including appearance, colour, fat content, taste, texture and tenderness. Whilst colour and fat content are important in influencing meat purchase, consumer studies indicate that it is the degree to which muscle tenderises after slaughter that is the most important factor contributing to overall meat quality (Warkup et al, 1995). Despite efforts to standardise breeding, husbandry, nutrition, transport, lairage and slaughter regimes, ensuring a consistently tender product still remains difficult to control or predict. The problem is international, with beefsteak toughness a major concern in the USA and pork toughness difficult to eradicate in the UK. The tenderisation process involves complex changes in muscle metabolism in the immediate post slaughter period and is dependent on genetic makeup, protein complement, metabolic status and environmental factors such as physiological stress. In the early postmortem period, glycogen depletion, lactic acid accumulation, pH decline and rate of entry and exit into rigor can all influence the ultimate tenderness of the meat some 8 - 20 days later following a period of conditioning (Goll et al, 1995). However, the main determinant of ultimate tenderness appears to be the extent of proteolysis of key target proteins within muscle fibres (Taylor et al, 1995). Research in all major livestock species has pointed to the calpain proteolytic enzyme family being a major factor responsible for key peptide bond cleavage (Koohmaraie, 1996). Whilst opinion is divided as to which isoform of calpain is the most important under specified conditions, most workers agree that the major factor is the level at slaughter of the specific calpain inhibitor calpastatin. The evidence for this is reviewed here, highlighting potential means of regulating the system in order to assure a consistently high quality tender product.