Nutritional deficiencies can have profound effects on the fertility and economic viability of dairy cattle. Phillippo et al. (1987) reported that molybdenum in the diet reduced the copper status of cattle and also delayed the onset of puberty, decreased the conception rate and caused anoestrus in cattle. A trial was set up at the University of Leeds farm to test the effect of supplementation with a soluble-glass bolus containing copper, cobalt and selenium on the reproductive performance of cattle.

Milking strategy and calf management vary depending on the requirements of the owner and the production focus. In Kenya, survey results have shown the camel (Camelus dromedarius) to be primarily managed for milk production but considerable variations in calf and milking management exist between pastoralist groups. The aim of this study was to compare two traditional calf management and milking systems and determine their effects on actual milk production.

Despite interest in the potential for fine fibre production from South American camelids in general and guanacos (Lama guanicoe) in particular there is little information currently available which would be relevant to their integration into UK livestock production systems. Without an understanding of their grazing behaviour on UK swards it is impossible to develop effective grazing management systems. This experiment was set up to compare the diet composition of guanacos and sheep when grazing a comparatively heterogeneous indigenous grassland community.

Digestibility studies conducted with South American camelids on conserved forages have identified lower intakes and higher digestion coefficients in comparison with sheep when fed low and medium quality diets (Hintz, Schryver and Halbert, 1973; San Martin and Bryant, 1989). However, such experiments often involve only one or two animals. There are no published reports of detailed comparative in vivo trials based on fresh forage. The aim of this study was to compare the voluntary intake and digestion coefficients of guanacos and sheep when zero-grazed on a comparatively high quality ryegrass sward at three different growth stages.

The use of metabolic profiles in livestock species is a well established technique for monitoring physiological changes, and determining the health status of individual animals. While reference ranges for serum biochemical values in llamas (Lama glama) (Lassen et al, 1986; Fowler and Zinkl, 1989) and alpacas (Lama pacos) (Simons, Waldron and Hennessy, 1993) have been published, equivalent data for guanacos (Lama guanicoe) are negligible. None of the studies which report values for metabolites in the blood of South American camelids have included a direct comparison with conventional livestock species. The aim of this study was to establish baseline ranges for metabolites in the blood of healthy guanacos, and to compare these with equivalent data for sheep.

Angora goats are efficient producers of hair fibre. They produce more fibre in relation to their size than sheep(Shelton et al., 1973). In skin and Mohair fibre cystine, which may be synthesised from methionine, is present in relative excess (5-10 times) to the other amino acids, when compared with major protein stores, such as skeletal muscle. Consequently a limitation in the supply of sulphur amino acids, may have disproportionate effects on the amount of nitrogen partitioned to other body tissues. The objective of this study was to investigate the effect of additional rumen protected intestinally available methionine in the diet on the partitioning of nitrogen between mohair and other body tissues in the Angora goat.

Lameness is a major welfare problem in farm animals. Lesions of the hoof arising from poor growth of hoof horn in dairy cows has been associated with inadequate keratinisation (Kempson and Logue, 1993). The sulphur amino acid cystine is an important component of hard keratins in sound hoof horn and hair fibre and is required in a quantity proportionately larger than that needed for most other body tissues. Cystine may be derived, in ruminants, directly from microbial and food protein or synthesised post-absorptively from methionine in the transulphuration pathway particularly in the liver. The objective of present study was to investigate the relative responsiveness of both hoof horn and mohair to methionine supplementation of the diet.

Biotin, a water soluble B vitamin, is essential for post- absorptive metabolism in animals. A deficiency of the vitamin is frequently associated with lesions of the skin and poor hair growth. Biotin may be supplied from the diet or by microorganisms in the digestive tract. The importance of dietary supply in pre-ruminant animals and the contribution of microorganisms from the rumen and elsewhere in the digestive tract following rumen development has not been adequately characterised.

Factors regulating the growth of Cashmere fibre and the hair follicle cycle are poorly understood. Insulin-like growth factors (IGFs) or insulin at higher concentrations, have been shown to stimulate in vitro growth of human hair follicles (Philpott et al, 1994). The role of such mitogens in the production of cashmere fibre by the Cashmere goat has not been previously investigated. The objective the study reported here was to investigate the growth of hair follicles in the absence and presence of insulin or IGF-I using our established in vitro technique.

Seasonal changes in secondary hair follicle activity and associated patterns of cashmere growth and moult are dependent on seasonal changes in profiles of hormones and growth factors. The aim of this study was to investigate the individual and interactive roles of prolactin and thyroid hormones in the activation of hair follicles and the onset of the spring moult.

Previous trials performed in temperate sown swards from New Zealand (Clark et al, 1982), from UK (del Pozo and Wright, 1995) and from Spain (Osoro and Martinez, 1995) showed improvements of sward clover contents on grass/clover pastures grazed by goats during the early part of the grazing season. However, this phenomenon might not occur to the same extent during autumn due to clover's poorer competitiviness with ryegrass. Additionally, Merchant and Riach (1994) showed that cashmere goats required pastures with mean sward heights to be above 6 cm to achieve aceptable levels of performance but were not able to considerate the implications of the sward legume content on their liveweight changes. The aim of this study was to investigate the effects of three contrasting sward height regimes and their associated relative changes in the vertical distribution of the sward clover proportion on the performance of cashmere goats grazing during the autumn season a lowland perennial ryegrass/white clover pasture located in Northern Spain.

Differences in grazing behaviour between sheep and goats could potentially be exploited in temperate sown swards to improve the efficiency of grazing systems (McGregor, 1985). However, integration of cashmere fibre goats with sheep in pastures from Northern Spain needs to be evaluated and compared with autoctonous breeds under different farming managements to allow assesments of the relative grazing profitability achieved on summer dry grass/clover pastures. The aim of the current study was to examine in lowland grass/clover swards the feasibility for animal performance of the integration of cashmere plus autoctonous goats with local sheep breeds under contrasting grazing managements (rotational, sequential or mix) with two different sward heights over a spring-summer period.

In November 1989, ten Suffolk breeders co-operated to establish a nucleus flock at Wye College, University of London, known as the Wye Suffolk Improvement Group (WSIG). The members contributed 10 ewes each to the base flock. The objective of the group was to produce breeding stock with lean carcasses for the current lamb market. The objective of this study was to estimate breeding values (EBV) of live animal traits, measured annually on the lamb crop, and to plot any genetic trends over a six-year period.

Lambs are born with a well developed hypothalamo-pituitary-thyroid system and are producing tri-iodothyronine (T3) and thyroxine (T4) in significant quantities by birth. Thyroid hormones are high in the newborn lamb and appear to play an important role in adaptation, by the lamb, to the extra-uterine environment. The aims of this study were to look at the effects of the thyroid hormones T3 and T4, on the neonatal lamb's ability to cope with the cold and its activity and vigour. Secondly to obtain preliminary estimates of the heritability of the two hormone concentrations and the lambs rectal temperature to see if they could potentially be useful indicators of the lambs genetic ability to thrive.

Dam genotype affects the phenotype of progeny through a sample of direct additive genes for growth and maternal effects on growth (Meyer, 1992). In this study (co)variance components due to direct and maternal effects were estimated for 50 day weight of Welsh Mountain lambs reared in a hill environment. The data set was based on ewes in an embryo transfer trial providing an opportunity to examine maternal effects based on larger numbers than usual of progeny per genetic dam.

The dam's milk production, mothering ability and the lamb's own genetic potential are important for preweaning growth. If there are strong maternal effects, which have not been separately accounted for, they can bias the estimates of heritability.

The objective of this study was to estimate genetic parameters for 12 week weights in Welsh Mountain lambs, and to assess the relative importance of the maternal genetic effect in this trait.

The UK sheep industry needs more information on the effect of ewe breed genotype on lamb output. Ewe genotype has been shown to affect prolificacy, dystocia, lamb viability, lamb growth rates and lamb carcass quality (Johnston, 1995). The aim of this experiment was to determine the effects of the proportion of Texel (T) or Rouge de l'Ouest (R) genes on lowland ewe productivity.

It is widely recorded that placental weight varies a great deal in uniformly treated ewes, yet this variation remains unexplained (Mellor, 1983). The aim of this experiment was to assess the effects of differing parameters on birth weight, placental weight, and number and weight of cotyledons in Texel ewes carrying the Booroola fecundity gene.

In Ireland, hay has been the traditional fodder offered to sheep during the winter period but the increasing tendency to house ewes before lambing has led to a substantial increase in the use of silage for this purpose. By-products are increasingly used as supplements to these forages, with little relative information available on their value. The objective of this experiment was to compare the effects of feeding grass silage and hay when supplemented with either barley, molassed sugar beet pulp or citrus pulp based concentrates to ewes in late pregnancy on feed intake, ewe weight and body condition changes, gestation length, litter birth weight and colostrum yield.

Winter shearing of ewes has been shown to reduce the incidence of hypoglycaemia in twin bearing ewes (Symonds et al, 1986), increase litter birthweight and reduce lamb mortality especially in housed conditions (Austin. 1982. Vipond et al, 1987). It is however not clear if winter shearing effects lamb birth weight independently of nutrient intake or reflects solely an increase in the intake of nutrients in late pregnancy. The aim of the experiment was to study the interaction between changing the source of energy in the concentrate given in late pregnancy and winter shearing in multiparous ewes.