Animals have predispositions towards the organoleptic properties, such as flavours, of the foods available to them. These predispositions can influence the feeding behaviour and diet selection of animals and prevent from, or enable them to select a diet that meets their nutrient requirements, in both short - and longer - run (Forbes and Kyriazakis, 1995). In this experiment, we investigated whether predispositions of sheep for novel food flavours could affect their diet selection when offered a choice between two foods with different nutrient content. The specific hypotheses tested were that such predispositions are: (i ) influenced by the nutritional quality of the food that are associated with, and (ii) affected by the current nutritional state of the animal.

The ability of animals to select appropriate levels of nutrients for growth or maintenance has been demonstrated in pigs ((Kyriazakis et al. 1990) and lambs (Glimp, 1971; Early and Provenza, 1998). However, there has been little research on the diet selection abilities of the horse, and it is often assumed, due to their many feeding related illnesses, that horses may not be well adapted to control intake or select their best diet. The aim of this study was to investigate the horse’s preference for cue flavours when associated with different energy concentrations and hence investigate the horse’s ability to associate flavours with post-ingestive consequences.

Sheep can use spatial memory to locate preferred food items in a background of less preferred items and forage more efficiently if the preferred patches are aggregated (Edwards et al. 1994). However, if a constant proportion of available patches contain food, foraging efficiency is not affected by the total number of patches (Edwards et al. 1996). The objective of this study was to test the hypothesis that spatial memory will be used to a lesser extent as the proportion of patches containing food increases. Not only is the animal faced with a potentially more complex task as the proportion of food patches increases but the cost:benefit ratio of using spatial memory is less. If 10 of 100 potential foraging sites contain food, an animal with perfect spatial memory could locate 5 of these patches in only 5 visits, whereas random searching requires 50 visits. If 50 patches contain food, 5 visits are required with perfect spatial memory but only 10 visits using random searching. Thus the benefit of using spatial memory over random search is reduced from 5:1 to 2:1.

4-tert-octylphenol (OP) is an alkylphenolic compound formed as metabolite of some nonionic surfactants that are widely used in industrial detergents, as plastic additives, dispersant for insecticides, etc. (Naylor et al., 1992). OP accumulates in adipose tissue. Micromolar concentrations of these compounds may constitute health hazards to animal cells. Furthermore, it has previously been shown to exert oestrogenic activity in vivo and in vitro (White et al., 1994). A growing concern about “endocrine disruptors” and their impact on oestrogen-dependent phenomena led us investigate the effects of OP on oocyte maturation. For variuos reasons bovine oocytes were chosen as the model system. We examined the effects of OP exposure on oocyte nuclear maturation in vitro and on the expression of oestrogen receptors in cumulus cells.

Polychlorinated biphenyls (PCB) are persistent environmental contaminants that have been reported to adversely affect reproduction in mammals. The exact mechanism of action of these chemicals on oocyte and embryo development are not known. Previous studies in our laboratory demonstrated that PCB adversely affect in vitro oocyte maturation and embryo development in two different in vitro systems (cattle, rabbit). The objective of present study was to investigate the possible role of the arylhydrocarbon receptor (AhR) in PCB toxicity. The AhR is a transcription factor activated by ligands such as dioxins or PCB. Its transcriptional activity depends on dimerisation with its nuclear partner ARNT. The presence of AhR and ARNT was investigated in bovine and rabbit genital tract (uterus, ovary) and embryonic tissues, employing RT-PCR and immunohistochemistry.

The use of controlled dietary intake for administration of environmental oestrogens to laboratory animals is essential in assessing the real threat of natural exposure to these compounds. Although human and animal exposure to environmental chemicals is mostly through diet or water, administration of these chemicals to laboratory animals is usually via injection. In this study, in order to overcome the problem of unpalatability of high doses of chemicals, a wax and a powdered diet were designed. These diets were used as vehicles for administration of the environmental oestrogen octylphenol (OP) to non-pregnant, pregnant and lactating laboratory rats and the dose of dietary octylphenol required to induce oestrogenic effects in the reproductive tract of female animals was determined.

Endocrine disrupting compounds (EDC) are chemically diverse and ubiquitous compounds which are released into the environment as a result of industrial, domestic and agricultural processes. They are generally readily absorbed from ingested food and water, can accumulate in animal tissue and can have adverse effects on reproductive and immune systems at very low concentrations. They are present in high concentrations in sewage sludge which is likely to be used increasingly as a fertiliser on pasture and arable land and so there is potential for bioaccumulation in animal tissues and associated, adverse biological effects. The aim of the study was to determine the concentrations of one EDC, dioctyl phthalate (DOP), in the livers of ewes and lambs maintained on control and sludge-treated pastures.

Hormonally active compounds of different origins such as polychlorinated biphenyls (PCBs) and their derivatives are widely dispersed in the environment by various industrial processes. They represent a threat to human health since their toxic effects can result from biological accumulation of low doses of active compound during extended periods of exposure. Critical doses for a cytotoxic effect have been determined using cellular models such as cultured hepatocytes but it is still not known if lower doses can affect in vitro cell functions before any toxic effect can be detected. To address this issue we have used a functional genomic approach to characterize changes in the profile of genes expressed by cultured bovine fibroblasts exposed during only 26 hours to concentrations as low as 10-10 to 10-12 molar of TCDD

Modern retailing of venison through supermarkets requires that the product be on the shelf for an extended period compared with the traditional short season in autumn/early winter. However, deer are highly seasonal animals and a range of strategies is needed to increase marketing opportunities for venison. One strategy utilizes extended winter daylength and high levels of nutrition to advance the slaughter season (Davies, 1995; Fisher et al., 1995). Another strategy is to adopt more natural, low input systems with reduced production costs, in which deer reach slaughter condition during their third summer at 22-26 months of age, but this needs full investigation. This study involved sequential slaughtering of deer to ascertain how rapidly carcass composition and meat quality changes over this period.

The EU is the second largest world producer of beef meat, but production is fragmented, consisting of highly variable local systems, compared with homogenous, highly intensive feedlot systems. The current EU agricultural policy requires a reorientation of beef market to take advantage of this diversity by creating meat quality labels relating to geographical areas and with specific genotype and production systems, symbols of guaranteed quality. The aim of this experiment was to analyse the relationships between productive and carcass parameters with some meat quality traits, within breed-production systems in different European countries.

The n-3 polyunsaturated fatty acids (PUFA) are healthy nutrients which can be increased in pork by feeding sources such as linseed to the growing animal. The levels achieved depend on many factors such as the concentrations of lipid classes in tissues (eg phospholipids containing high PUFA levels are more abundant in muscle than adipose tissue) competition for incorporation with n-6 PUFA and possible inhibitory effects of PUFA on synthesis of saturated and monounsaturated fatty acids. This study examined the time course of the incorporation of n-3 PUFA into tissue lipids and the effects on the major synthetic enzyme D9-desaturase. The effects on pork odour were also studied.

The fatty acid and vitamin E concentration in the diets of growing pigs are known to affect backfat and meat quality. The aim of this study was to determine the effects of substitution of a carbohydrate dietary source (maize) by a series of oils on the fatty acid (FA) composition of backfat and marbling fat at slaughter. Vitamin E concentration in muscle (longissimus dorsi ) was also determined.

Calpastatin is the endogenous inhibitor of the calcium-dependent protease family known as calpains and is thought to be an important determinant of postmortem tenderisation rates in beef, lamb and pork (Koohmaraie, 1996; Parr et al, 1999). Regulation of calpastatin is therefore of great importance if efforts to overcome unpredictable incidences of pork toughness are to succeed. Recent evidence in ovine tissue has shown that calpastatin is susceptible to fragmentation by calpains (Doumit and Koohmaraie, 1999). The ability of calpain to fragment calpastatin in porcine tissue was investigated and the consequences for pork quality are considered.

High concentrations of skatole in adipose tissue are a major factor in boar taint - the offensive odor and taste in cooked pork from some intact male pigs. Skatole is produced by bacterial fermentation of tryptophan in the large intestine, absorbed into the blood and transported into the liver, where it can be metabolised via the cytochrome P450 system. One reason for high skatole levels in pig adipose tissues could be low expression of hepatic cytochrome P450IIE1 in liver and hence a reduced rate of skatole clearance, but no correlation was found between the rate of skatole metabolism and the P450IIE1 content of isolated liver microsomes. The present study re-investigates the relationship between backfat skatole, liver P450IIE1 expression and the rate of microsomal skatole metabolism in two breeds of pigs.

Legumes, such as red and white clover, are potentially important constituents of low input, environmentally friendly beef production systems. However, the effects of grazing clover on the quality of beef have not been assessed fully. Important aspects of meat quality are shelf-life (colour and lipid stability), flavour and human nutritional value, all of which are affected by components of the animals diet such as antioxidants and fatty acids. Tissues from lamb finished on swards containing white clover were reported to contain more linoleic and a-linolenic acid and less eicosapentaenoic acid (EPA, 20:5 n-3) (Vipond et al., 1993) compared to animals grazing grass. The objective of this study was to determine the quality of meat from two beef breeds raised on grass or grass plus white or red clover.

Increasingly the market demand is for carcasses of better conformation which is reflected in carcass prices. Therefore the breeding policy for suckler herds must reflect market requirements. This study examined the usefulness of ultrasonic scanning and muscle scoring in predicting carcass conformation, fatness and meat yield.

Carcass fat of meat producing animals has long been identified as one of the most important characteristics of overall meat quality. In this respect, consumer choices of particular food reflect their awareness of the link between health and consumption of fats particularly saturated. Lamb meat is considered to be excessively fat and this results in substantial loss in its marketability. This study was carried out to assess the effect of breed, sex, post-weaning nutrition, live weight at slaughter and their interactions on the fatty acid (FA) composition in carcass fat of lambs of three indigenous dairy Greek breeds of sheep.

There is increasing interest in the use of red clover (Trifolium pratense) as a high protein forage crop to finish growing lambs. Red clover contains the isoflavanoid compound formononetin which is converted to the non-steroidal oestrogen analogue equol by rumen micro-organisms. Equol is absorbed by the animal, and can have significant effects, such as suppressing reproductive cycling in ewes. Very few commercial red clover varieties have been bred with a low formononetin content to prevent this problem. Although human health benefits have been linked to the consumption of oestrogenically active compounds in foods such as soya (Kurzer and Xu, 1997), there is a need to investigate the presence of oestrogenically active compounds in animal products. The objective of this study was to investigate plasma metabolite and hormone concentrations, and the residual levels of equol in meat, of lambs grazing two varieties of red clover differing in their formononetin contents, compared to control animals grazing grass.

Proteolytic degradation is known to be faster in white muscles than in red muscles (Whipple & Koohmaraie, 1992). Variation in eating quality between muscles has often been correlated to their metabolic properties, as determined by the fibre type distribution. Correlations between fibre type distribution and postmortem proteolysis could result from two possible effects: (1) Due to their inherent differences in metabolic potential, composition and content of proteolytic enzymes, fibres of some types may degrade more than others. (2) The balance of fibre types controls postmortem (p.m.) metabolic characteristics of the muscle as a whole, with all fibre types within it being equally affected. An experiment was conducted to compare the rate of postmortem proteolysis in five porcine muscles differing in fibre type distribution and to compare the rate of proteolysis in type II fibres isolated from these muscles.

It is desirable to increase the level of conjugated linoleic acid (CLA) in milk as a health benefit in human nutrition. CLA has been shown to affect carcinogenesis, atherosclerosis, diabetes, the immune system, bone mineralization, body fat accretion and nutrient partitioning. The predominant CLA isomer present in foods from ruminants is cis-9, trans-11 CLA. It is formed in the rumen by anaerobic bacteria as an intermediate in the hydrogenation of linoleic acid. Recent evidence has shown that CLA can also be produced in the mammary gland by desaturation of trans-11 C18:1. Previous researchers have used various oils or oil seeds to try and elevate CLA levels in milk. A problem with this approach is that most oils contain mixtures of fatty acids so responses cannot be attributed to individual acids. Up to now there has been no report looking at how individual fatty acids affect CLA production. The objective of this work was to separate the effects of linoleic and linolenic acids on CLA production in dairy cows.