Nugent R A, Notter D R, Beal W E
Dept. of Anim. Sci., Virginia Polytechnic Institute and State University, Blacksburg 24061.
J Anim Sci. 1988 Jun;66(6):1363-70. doi: 10.2527/jas1988.6661363x.
Two groups of purebred ewes (A and B), each consisting of 25 Dorsets and 25 Hampshires, were used to study effects of ewe breed and ram exposure on ovulation and estrus in May and June. Ewes lambed in January and February and were isolated from mature rams for at least 5 mo. From May 8 to June 11 (Period 1), Group A ewes were penned with vasectomized rams fitted with marking harnesses and Group B ewes were isolated from rams. From June 11 to July 13 (Period 2), rams were placed with Group B ewes and Group A ewes were isolated from rams. Ovulation was monitored by biweekly serum progesterone assays and crayon marks were used to detect estrus. For Group A ewes in Period 1, more Dorsets ovulated (96%) than did Hampshires (72%), and of ewes that ovulated, more Dorsets mated (83 vs 28%). Fifty-five percent of Dorsets, but only 20% of Hampshires, appeared to have been spontaneously cycling at the start of the experiment. Of ewes mated in Period 1, more Dorsets than Hampshires continued to cycle during Period 2 (65 vs 0%). For Group B ewes in Period 1, 44% of Dorsets, but only 8% of Hampshires, ovulated in the absence of rams. In Period 2, 92% of Dorsets and 84% of Hampshires ovulated. Of ewes that ovulated, more Dorset ewes mated (78 vs 52%). Of ewes that mated, more Dorsets appeared to be cycling spontaneously at ram introduction (39 vs 0%). Throughout the study, 24% of Dorsets, but no Hampshires, cycled continuously.(ABSTRACT TRUNCATED AT 250 WORDS)
两组纯种母羊（A组和B组），每组各有25只多塞特羊和25只汉普夏羊，用于研究母羊品种和公羊接触对5月和6月排卵及发情的影响。母羊在1月和2月产羔，并与成年公羊隔离至少5个月。从5月8日至6月11日（第1阶段），A组母羊与佩戴标记背带的输精管结扎公羊圈养在一起，B组母羊与公羊隔离。从6月11日至7月13日（第2阶段），公羊与B组母羊放在一起，A组母羊与公羊隔离。通过每两周一次的血清孕酮检测监测排卵情况，并用蜡笔标记检测发情。在第1阶段，A组母羊中，多塞特羊排卵的比例（96%）高于汉普夏羊（72%），在排卵的母羊中，多塞特羊交配的比例更高（83%对28%）。55%的多塞特羊，但只有20%的汉普夏羊，在实验开始时似乎处于自发发情周期。在第1阶段交配的母羊中，多塞特羊在第2阶段继续发情的比例高于汉普夏羊（65%对0%）。对于第1阶段的B组母羊，44%的多塞特羊在没有公羊的情况下排卵，但只有8%的汉普夏羊排卵。在第2阶段，92%的多塞特羊和84%的汉普夏羊排卵。在排卵的母羊中，多塞特母羊交配比例更高（78%对52%）。在引入公羊时，交配的母羊中，多塞特羊似乎自发发情的比例更高（39%对0%）。在整个研究过程中，24%的多塞特羊持续发情，但汉普夏羊没有。（摘要截选至250字）
