Haemoglobin genotype, reproductive performance and response to PMSG in sheep.

ewes to superovulatory doses of PMSG. A subsequent report of a similar study of Welsh mountain ewes found no association between Hb type and response to PMSG (Trounson, Willadsen, Moor & Tucker, 1976). Egg-transfer experiments with Finnish Landrace (Finn) and Galway donors provided an op¬ portunity to extend the findings of Pant & Pandey (1975) and Trounson et al (1976). In addition to typing all donor ewes, 5 pedigree Galway rams and all male and female individuals of the Texel and Lleyn breeds in our flocks were typed. The Galway, Texel and Lleyn breeds are similar in type and probably have common ancestry. The Finn ewes were representative of our stock and most of the Galway ewes had been selected as donors because of an outstanding fecundity record (best 5 % of the population). Lleyn sheep were also highly selected on the basis of a prolificacy index. The Texel animals were unselected on previous performance. The Finn and Galway ewes were induced to superovulate by an intramuscular injection of 1500 i.u. or 2000 i.u. PMSG (Folligon: Intervet) on Day 12 or 13, respectively, of the oestrous cycle. These doses are equivalent per unit metabolic body size. The response to PMSG (the number of CL and large follicles > 6 mm diam.) was observed at laparotomy for egg recovery and data were available for the egg-recovery and fertilization rates. The natural ovulation rate had been recorded