Nugent R A, Notter D R
Dept. of Anim. Sci. Virginia Polytechnic Institute and State University, Blacksburg 24061-0306.
J Anim Sci. 1990 Jun;68(6):1513-9. doi: 10.2527/1990.6861513x.
Two groups of 24 Hampshire and 26 Suffolk purebred ewes each were used to study effects of cohabitation with cyclic white-faced (WF) ewes on estrous activity in June. Ewes lambed in January, February and March and had been isolated from mature rams since the previous fall breeding. From June 1 to July 2, treated (T) ewes were exposed to vasectomized rams and to 65 WF ewes; control (C) ewes were exposed only to vasectomized rams. Ovulation was assessed with biweekly serum progesterone assays; crayon marks were used to detect estrus. Daily observations of ram behavior were conducted to assess sexual activity of rams joined with T and C ewes. Cohabitation with WF ewes increased (P less than .01) ovulation percentages from 46% in C (42% for Hampshires and 50% for Suffolks) to 76% in T ewes (79% for Hampshires and 73% for Suffolks). Mating percentage also was increased (P less than .05) by cohabitation with WF ewes from 14% for C ewes to 30% for T ewes. Rams with T + WF ewes spent more (P less than .05) time checking ewes for estrus than did rams with C ewes. Hence, cohabitation with cycling WF ewes increased ovulation and mating percentages. Many acyclic T ewes first ovulated after 10 or more days of teasing, possibly due to increased ram contact in the presence of WF ewes.
两组母羊，每组分别有24只汉普郡母羊和26只萨福克郡纯种母羊，用于研究在6月与处于发情周期的白面（WF）母羊同居对发情活动的影响。母羊在1月、2月和3月产羔，自去年秋季配种后便与成年公羊隔离。从6月1日至7月2日，处理组（T）母羊与输精管结扎的公羊以及65只WF母羊接触；对照组（C）母羊仅与输精管结扎的公羊接触。通过每两周一次的血清孕酮检测来评估排卵情况；用蜡笔标记来检测发情。每天观察公羊的行为，以评估与T组和C组母羊在一起时公羊的性行为。与WF母羊同居使排卵率从C组的46%（汉普郡母羊为42%，萨福克郡母羊为50%）提高到T组母羊的76%（汉普郡母羊为79%，萨福克郡母羊为73%）（P小于0.01）。与WF母羊同居也使交配率从C组母羊的14%提高到T组母羊的30%（P小于0.05）。与T + WF组母羊在一起的公羊比与C组母羊在一起的公羊花费更多时间（P小于0.05）检查母羊是否发情。因此，与处于发情周期的WF母羊同居可提高排卵率和交配率。许多非发情周期的T组母羊在经过10天或更长时间的逗引后首次排卵，这可能是由于在有WF母羊在场的情况下与公羊接触增加所致。
