The availability of high quality pasture for mating is frequently limited in hill farming systems. The majority of ewes usually conceive during their first oestrous cycle after ram joining. More effecient use might therefore be made of better grassland if ewes could be successfully returned to their hill grazings part way through the mating period. This would allow either a longer period of availability of improved grass before ram joining or more logically access by a larger number of ewes to the improved grassland area.

Efficient management techniques in sheep production must take particular account of the pattern of reproductive behaviour and its application in the manipulation of reproductive processes. Conventionally in the UK, the advancement of the breeding season has been achieved by the use of progesterone-impregnated sponges and pregnant mare's serum gonadotrophin (PMSG). The ‘ram effect’ has been shown to be a powerful and cheap way of controlling the time of mating of sheep. The objective of the present study was to investigate the value of using different methods of teasing for the stimulation of ovarian activity in an early lambing flock.

Population studies have shown useful correlations between alleles at the casein loci and important production parameters such as compositional characteristics of milk, cheese yield and lactation yield. Molecular genetic analysis of genotype at the casein loci could therefore enhance sire selection in dairy herds. We are Investigating polymorphisms in K-casein, where the B-variant gives improved cheesemaMng and in β-casein, where the A3 allele is associated with improved lactation yields. We have previously reported a restriction fragment length polymorphism in the K-casein gene, enabling us to identify the alleles at this locus [Perry, B.N., Savva, D., Radley, E., Skldmore, C.J. & Lovell, R.D. (1989) Anim. Prod. 48, 661]. Our current work makes use of the polymerase chain reaction (PCR) to increase dramatically the speed of di agnosis.

The increasing international exchanges of semen and embryos have made it necessary to develop methods for converting bull and cow evaluations from the scale in the country of export to the scale in the country of import. Methods were Initially recommended by the International Dairy Federation (IDF, 1983) and latterly by the International Bull Evaluation Service (Interbull),(Philipsson et al, 1986).

The Interbull recommended methods were compared using United Kingdom (UK) data and one, known as the Goddard method was selected for routine use (Swanson, Bellamy and Oliver, 1988). These methods dealt with direct comparisons whereby progeny test evaluations for the same bulls were available In the two countries for which a conversion was required. In situations where this information is not available or is limited, an indirect conversion involving a third country may be calculated.

The slaughter of male chickens at hatching in the egg industry constitutes a considerable financial loss. Although there is a close phylogenetic relationship with the chicken, the alligator displays the unique phenomena of temperature dependent sex determination i.e. the temperature of egg incubation determines the sex of the progeny (1). A comparison of chicken and alligator embryo metabolic data may thus suggest ways through which the sex determination operates and may be applied to the chicken. In the chicken and the alligator the lipids of the yolk perform a vital role as an essential nutrient and energy source to the developing embryo (2). As part of a wider research programme on temperature dependent sex determination, comparative data has been obtained on aspects of yolk lipid metabolism in the two species.

Aitrenogest (17 α -allyl-17-hydroxyestra-4,9,11-trien-3-one; Regumate Porcine; Hoechst Animal Health) is a synthetic progestagen which has been used to control and synchronise the ovarian cycle particularly in cyclic gilts. However progestagens have also been used in various species to induce and synchronise the first ovulation post partum. The present study was undertaken to determine the effect of altrenogest treatment on the reproductive performance of primiparous sows.

The objective of this study was to examine the time course of changes in plasma β-endorphin and Cortisol in sheep transferred to a new environment. Three ewes and three wethers were transferred from pasture to indoor crates for a nine-week period. Blood samples were taken hourly for 24h periods once a week. β-endorphin and cortisol were measured by radioimmunoassay. Changes in hormone concentration over time were analysed by analysis of variance procedure for repeated samples. Other data were analysed by analysis of variance and Duncan's multiple range test. Mean β-endorphin concentration was significantly (P<0.001) higher in females than males at the start of the trial (1108±123 v 623±162 pg/ml). By day 60, female levels had fallen to 750±77 pg/ml but male levels were almost unchanged (561±190 pg/ml). Neither change was statistically significant. There were no significant changes in β-endorphin pulse frequency (3-4 pulses/24h) or amplitude (600-1300 pg/ml).

Approximately 480,000 maiden heifers surplus to herd replacements are slaughtered annually for beef in Ireland. They comprise approximately 150,000 Hereford and Angus x Friesians, 150,000 continental x Friesians, 100,000 Hereford and Angus crosses from the suckler herd and 80,000 continental crosses from the suckier herd. At times of calf scarcity and high prices some of these heifers could be bred to produce a calf before slaughter. Provided that calved heifers are slaughtered before 30 months of age, there is little difference in meat quality between such animals and maiden heifers slaughtered at 18 to 24 months of age (Joseph, 1975). The objective of the present experiment was to quantify the productivity of once calved heifers finished indoors or at pasture.