Lower reproductive efficiency of buffalo than that of cattle hampers efficient utilization of tropical buffaloes. Heat detection in buffaloes poses problem because overt signs in buffaloes are of less intense and of shorter duration than in cattle. Moreover, buffalo tends to exhibit overt signs during night or early morning and most farmers are ignorant of physical signs of estrus. Inhibin, a glycoprotein hormone produced by ovarian granulosa cells, suppresses production and / or secretion of FSH through negative feedback effect at pituitary level (Burger, 1992). There is no information available on comparison of peripheral plasma inhibin profiles in Sahiwal cows and Murrah buffaloes reared under identical feeding and management condition. The present study was, therefore, designed to compare inhibin profiles in Sahiwal cows and Murrah buffaloes reared under tropical condition.

Progesterone and progestagens are widely used to synchronise oestrus in sheep, however 15 to 30 % of ewes fail to maintain a pregnancy following the first service after oestrous synchronisation and the reason(s) for this failure rate is unclear. In commercial flocks, the progestagen treatment commences at a random stage of the oestrous cycle and in some ewes luteolysis may occur soon after treatment commences, leaving the ewe solely dependent on the exogenous source of progestagen which promotes the development of persistent follicles (Flynn et al., 2000). These persistent follicles may be up to 14 days of age when they ovulate whereas the age of follicles at ovulation in natural cycles is 4 to 8 days. In cattle, it is clear that ovulation of these old follicles results in a decrease in fertility. The aim of this study was to examine the effect of ovulation of aged follicles on fertility in cyclic ewes by using treatments based on a 14-day, progestagen synchronisation protocol that is known to produce persistent follicles.

Sheep group breeding schemes have gained in popularity in recent years. The objectives of group breeding schemes are to improve desirable traits such as carcass conformation, weight and maternal ability whilst maintaining local type. However, if group breeding schemes were to work together then a larger genetic pool of performance recorded animals would be available to facilitate improvements. The objectives of this project were therefore twofold, 1.) was to improve traits such as weight and carcass conformation and 2.) to demonstrate the benefits of cooperative groups working together. In this project, group breeding schemes from North and Mid Wales have been working together with ram performance testing groups from North, South and Mid Wales to improve results from Welsh Mountain breeding schemes.

In recent years genetic improvement programmes for sheep in the UK have been primarily directed towards the improvement of growth and carcase traits. The possible correlated responses in other production traits, that may not be of such obvious economic importance, have not been fully assessed. Birth weight is such a trait.

Although of no direct economic importance, birth weight is an important trait in sheep production. There is a known relationship between birth weight and lamb survival, with lambs of both low and very high birth weight being at greater risk. There have, however, been very few genetic studies of the trait. The aim of this study, which is part of a larger project covering a number of breeds, was to estimate the direct and maternal heritability of birth weight and its genetic correlations with 8 week weight in the Dorset Down and Hampshire Down breeds. In addition the genetic trend in birth weight over a fourteen year period is assessed.

In view of the stratified nature of the sheep industry, changes in breeding policies in the hill sector impinge on the performance of the lowland sector. Carson et al (2000) investigated the effect of choice of ram and ewe breed on lamb output and carcass quality in the hill sheep sector. First cross (F1) ewes were produced as a result of crossing Scottish Blackface and Cheviot ewes with a range of ram breeds. The primary objective of the present study was to provide information on the performance of these crossbred females in terms of lamb output and carcass quality and thus determine the impact of changing hill genetics on all strata of the sheep industry. Within the terminal sire breeds significant improvements in lean growth potential have been made through genetic improvement schemes. The secondary objective of this study was to provide information on the effects of using high lean growth index rams on lamb growth and carcass quality.

Reproductive failure is a source of major economic loss to the UK pig industry, accounting for 0.5 of all first parity gilt cullings (MLC Pig Year Book, 1995). Previous research (Cameron et al, 1999) has shown that rearing gilts on a diet formulated to support maximal protein deposition has beneficial effects on ovulation rate at 3rd oestrus. The aim of the current experiment was to develop further the previous model to assess long and short-term effects of protein nutrition on reproductive performance, body composition and metabolic status.

The accurate replication in vitro of bovine mammary gland function would be of enormous benefit to studies investigating the control of milk synthesis and secretion. However, progress towards this end has been slow, partially because of the biological variability in the cell preparations produced to date. In particular, the heterogeneous nature of primary cultures of mammary epithelial cells (MEC) makes them unstable for repeated experimentation over time, while for immortalised cell lines in vitro the level of milk protein production is either very low or non existent; if it does occur it has been independent of in vivo factors known to regulate mammary growth and milk secretion. The aim of this project was to establish a bovine MEC non-immortal clone, which is both responsive to mitogens and functionally responsive to lactogenic hormones and an appropriate extracellular matrix.

Endocrine disrupting compounds (EDC) include a diverse range of chemicals derived from industrial, agricultural and domestic processes (IEH, 1999). They include phthalates (used in the manufacture of plastics), alkyl phenols (present in detergents and surfactants), polychlorinated biphenyls (PCB; formerly used in electrical equipment), dioxins (released from incinerators), organochlorine pesticides and organohalogens (used as flame retardants).

The compounds have a wide range of chemical structures but all of them have the capacity to disrupt normal hormonal actions. In some cases they bind to steroid hormone receptors and so they can have weak oestrogenic or androgenic effects while others disrupt thyroid hormones or other physiological functions. Consequently, they may disrupt reproductive or immune function and can be carcinogenic.

Evidence of adverse effects on animal physiology is partly circumstantial and partly based on empirical studies, mostly involving laboratory rodents. Many reports in the literature indicate that reproductive disorders in wildlife species such as pelicans, birds of prey and polar bears are associated with abnormally high concentrations of EDC in their tissues. Furthermore, controlled studies involving the administration of large, arguably pharmacological, doses of EDC to laboratory rodents have demonstrated adverse effects on their reproductive or immune systems. Relatively little work has yet been done to determine the pattern of uptake and bioaccumulation of EDC in domestic species or the effects of EDC on the physiology of these species.

Fifty percent of Dutch dairy farmers use surface water as the main source of drinking water for their cows during the grazing season. In many locations this surface water is in direct contact with a sewerage overflow. Belfroid and coworkers (1999) have demonstrated that this sewerage overflow surface water contains EDC, in particular xeno-oestrogens. The concentration of conjugated ethinyl-oestradiol, for example, in sewerage water was 0.02 mg/l. During the last decade the fertility of dairy cows has decreased dramatically. There is an increased incidence of cystic ovaries, an increase in the interval from calving to first insemination, an increase in the number of inseminations per pregnancy and more abortions have been recorded. These observations raise the possibility that EDC’s adversely affect reproduction in dairy cows. Meijer et al. (1999) compared the production and fertility of cows on 397 farms that used normal surface water with the production and fertility of cows on 60 farms that used water in direct contact with sewerage overflow. The results showed clearly that cows drinking water that was in direct contact with sewerage overflow produced less milk and had a greater age at first calving. Moreover they exhibited a tendency towards a longer interval between calving and first succesful insemination and tended to have a higher rate of abortions. Boerjan et al. (2001) have recently addressed the issues of concentrations of xeno-estrogens present in soil, in plants, in water and in cow tissues, milk and blood, in order to assess the potential risk to ruminants of xeno-estrogen exposure through soil and water ingestion. Although data are sparse and concentrations of EDC in feed and water of ruminant animals are low, under certain circumstances such as sewerage overflow and sludge-fertilized pasture, they concluded that rates of ingestion of certain xeno-oestrogens may exceed levels at which there is no effect. Since most EDC’s are lipophilic and become concentrated in adipose tissue, the mobilisation of fat during onset of lactation and pregnancy can expose animals to much higher concentrations of xeno-estrogens than are present normally in the environment. Important questions are:

1. 1) how much of the EDC’s stored in fat cells will enter the blood under certain circumstances

2. 2) how much of the EDC’s in soil, water and plants will pass the rumen and enter also the blood and

3. 3) how potent are the different EDC’s i.e. what is the dose response relationship? In order to answer the last question an in vivo animal-model is urgently needed.

We have developed an animal-model, based on the genital tract of an ovariectomized cow; the height and organisation of the endometrial lumen-epithelium, the rate of oedema in the stratum compactum and the electrical resistance of the cervical mucus are sensitive measures of oestrogenic activity.

Concerns have been raised about the potential adverse effects on reproductive health in farm animals, humans, and wildlife species from a range of environmental chemicals that disrupt normal hormonal actions. The alkylphenol polyethoxylates are non-ionic surfactants used in the manufacture of detergents, paints and herbicides. During sewage treatment, these compounds are broken down to short chain alkylphenol polyethoxylates, alkylphenol carboxylic acids and alkylphenols which bioaccumulate in the lipid of living organisms. The estrogenic nature of one of these compounds - octylphenol has been clearly demonstrated in cell culture, in a recombinant yeast screen with human estrogen receptor?and in animal studies. It is proposed that these endocrine disrupting compounds influence male adult reproductive potential by disrupting the development of the hypothalamic-pituitary-testicular axis during fetal life. We have recently identified that exposure to octylphenol for the second half of gestation decreases circulating concentrations of FSH during fetal life and the number of Sertoli cells of the testis and testis size at birth in comparison to control animals (Sweeney et al., 2000). However, the testes size, % interstitial space, semen volume, semen concentration and % live semen was similar in both treatment groups in the adult. In contrast animals exposed to octylphenol from birth to weaning (16 weeks of age) had a significantly greater number of primary and secondary abnormalities in comparison to controls and animals exposed to octylphenol for the second half of gestation. A number of the animals exposed to octylphenol from birth to weaning exhibited augmented sexual behaviour, while those exposed to octylphenol for the second half of pregnancy showed a suppression of sexual behaviour. The current data suggests the physiological effect of exposure to octylphenol is dependant on the time and duration of exposure. This has major implications for the determination of universal end-point measurements to assess exposure to endocrine disrupting compounds.

Over recent years increasing evidence suggests that xeno-oestrogens including alkylphenols, such as nonylphenol and octlyphenol (OP), may represent a threat to the health and reproductive function of humans, domestic animals and wildlife populations. To date most attention has focused on the effect of these endocrine disrupting compounds (EDCs) on male reproductive health. In contrast, hardly any attention has been paid to the potential adverse effects that these compounds may exert in females, where the end points are easier to measure than in males, and where oestrogen modulated diseases such as breast cancer, are of such importance to humans. This is also despite evidence from a number of species, including humans, that exposure in utero to the potent synthetic oestrogen diethylstilbestrol (DES) has profound and long-term effects on ovarian morphology, folliculogenesis, fertility, and pregnancy outcome of female offspring.

For over thirty years livestock improvement programmes have exploited mainly statistical technology for the process of selective breeding. This has been safe, non-controversial, and highly cost-effective. The present revolution in knowledge of DNA now offers the possibility of much faster change in a wider range of traits, including meat quality and disease resistance which are difficult to measure in the live animal. However this new technology presents a threat as well as an opportunity. This paper examines the possible role of the new technology in genetic improvement, and considers the scientific strategy that the industry should adopt.

The United Kingdom, and much of the rest of Western Europe, has seen a series of food “crises” over the last 10-15 years, which have shaken consumer confidence in the safety of the food they purchase. Such concerns have also led to the establishment of Food Safety/Standards Agencies in a number of European countries. The most serious food safety issue has been BSE, which has claimed the lives of many thousands of cattle and almost 100 people in the UK. The rise of BSE coincided with the appearance of highly pathogenic bacteria, such as Salmonella Enteritidis phage type (PT) 4 and Escherichia coli O157:H7. Campylobacter spp. also became highly important zoonotic pathogens during this period.

There is a public belief that the above bacterial pathogens, and BSE, gained a foothold in animal production as a consequence of the intensification of the industry. Although this is an over-simplification, there is no doubt that the presence of a large number of potential host animals in the same place at the same time facilitates both infection and horizontal transmission. Food safety cannot be separated from the economics of production, however, and with ever-falling profit margins farmers must find the most economical ways of producing animals. The unit costs of intensive production will often be lower than with extensive systems and thus it is highly likely that intensive animal production will continue. Does intensification necessarily mean unsafe? Is it possible to produce food at an affordable price that is free from microorganisms that are potentially pathogenic for man? These and other issues will be discussed with particular emphasis on Salmonella, Campylobacter and E.coli O157:H7.

We can produce the tenderest, tastiest, highest welfare beef, pork and lamb in the world but if the consumer wants to buy chicken and fish, so what!

The changes that have taken place in what consumers can purchase and what and where they eat are nothing short of phenomenal and on-going.

In the 1950s families ate at least one cooked meal together every day, as they had for most of the century. The focus of this meal, lunch, dinner, tea or evening meal, depending on where you lived, was meat and two veg. All of this was cooked from scratch by the housewife, who had probably bought all the ingredients freshly that day.

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.

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.

For most common meats, the most important aspects of eating quality that determine overall acceptability are taste (flavour), texture (especially toughness/tenderness) and juiciness (water-holding). Unexplained variations in tenderness and water-holding are two of the consistent problems in the industry and sources of consumer dissatisfaction. A basic understanding of the causes of variability in toughness and water-holding is therefore important to the meat industry, because an understanding of the mechanisms controlling these aspects of eating and processing quality is desirable if we are to reduce undesirable variations and ensure high acceptability. Despite considerable research in the last century, we have met with only partial success in explaining the causes of such variations. This warns us that the complete picture is multivariate and complex. Toughness and water-holding are in fact both properties determined at several levels of structure within muscle tissue, from the molecular, through to macroscopic. Our current programme of research contains several related areas of work which aim to further our understanding of the structural mechanisms at several levels of organisation which cause variations in tenderness and water-holding of whole meat.

Computer tomography (CT) scanning is a method for non-invasive imaging of subjects developed for use in human medicine. It allows cross-sectional images, containing a wealth of information, to be obtained for a living animal (Davies et al., 1987). These can be used to provide very accurate assessment of body composition in live animals in a welfare-friendly manner. Not only is accuracy improved but also a wide range of novel traits lend themselves to assessment and objective measurements can be collected rapidly, using mathematical algorithms for image analysis (Glasbey & Robinson, 1999; Glasbey et al., 1999).

The perception of milk has changed over the past 25 years from one of being the ideal food to one of being detrimental nutritionally, mainly due to the fatty acid composition of its fat component. Now however, it has been discovered that milk contains a number of compounds, which may have positive nutritional benefits. It also appears that the association between saturated fatty acids in milk and effects on cholesterol may have been an oversimplification. It is accepted that the hypercholesterolaemic saturated fatty acids in milk fat are confined to lauric (C12:0), myristic (C14:0) and palmitic acid (C16:0) with the shorter chain saturated fatty acids and stearic acid having no cholesterol raising effect. Indeed bovine milk fat contains two fatty acids which may have important beneficial effects on human health, namely conjugated linoleic acid (cis- 9, trans- 11 linoleic acids – C18:2, CLA) and butyric acid (C4:0). Also monounsaturated fatty acids have been shown to be beneficial in altering the proportions of LDL and HDL cholesterol and it is possible to increase the concentration in milk of the principal monounsaturated fatty acid, oleic acid (C18:1), by optimising the diet of the cow. This paper will discuss nutritional strategies to optimise milk fat composition with particular reference to work from my own Research Centre in relation to oleic acid and CLA.

Meat and milk production from farm animals is dependent in part on fetal development and post-natal growth of specific tissues. This paper will review some of the systems controlling both muscle and mammary growth which are related to meat and milk production and some of the genes known to regulate these production traits.