Reproduction Abstracts

Many studies demonstrating that the environment a pregnant female experiences can have profound and sometimes persistent effects on offspring development use extreme experimental perturbations which do not reflect the range of environments a pregnant female is actually likely to experience. We have assessed offspring reproductive development following treatments designed to reflect husbandry and management conditions that pregnant sheep or pigs encounter. Female offspring of sows that were mixed with unfamiliar older sows for two, 1-week periods during mid-pregnancy had fewer primordial ovarian follicles, while male offspring had lower oestradiol and testosterone concentrations. Provision of an enriched environment during the first month of life to prenatally stressed male piglets did not alter their reproductive hormone concentrations, suggesting that post-natal treatments do not always modify prenatal effects. Our sheep studies compared offspring of ewes reared in conditions reflecting the range of husbandry conditions on UK farms. Ewes reared in ways that mimicked poorer husbandry had a high stocking density, more competition for food and were mixed. Those managed in line with best practice had lower stocking density, longer feed troughs and remained in stable groups. At puberty, male lambs born to ewes managed in the poorer environment had heavier and larger testes with larger seminiferous tubules and tended to have greater LH receptor gene expression, more Sertoli cells and fewer Leydig cells compared to contemporary male lambs carried by mothers reared according to best practice. These studies suggest that the range of husbandry conditions in current farming systems is sufficient to program reproductive development.