Effects of post-mating environmental stress or administration of ACTH on early embryonic loss in sheep

Abstract

SummaryIn two separate experiments, ewes of the Scottish Blackface breed were subjected to management stresses in the first or second 10-day period after mating or were treated with daily injections of 60 i.u. ACTH for the whole 20-day period. Embryonic loss is defined as the number of corpora lutea not represented by viable embryos at slaughter. Examinations were carried out between 26 and 32 days post-mating. In the two experiments combined, losses were 29·9, 29·0, 37·7 and 17·2%, respectively, for ewes subjected to environmental stress during days 1–10, during days 11–20, treated with ACTH or kept as unstressed control. Expressed as the percentage of ewes in which partial or complete loss of shed ova occurred, the results were 49·0, 46·0, 54·3 and 25·5%, respectively. Losses were significantly higher in all treated groups than in the unstressed control.