Quirke J F, Bradford G E, Famula T R, Torrell D T
J Anim Sci. 1985 Dec;61(6):1421-30. doi: 10.2527/jas1985.6161421x.
Ovulation rate was measured by laparoscopy at two consecutive cycles on 366 ewes 2 yr old and over and 85 yearling ewes of five lines of Targhees from the base base population; 53 yearling linecross ewes were also included. The lines were two unselected controls (HCl and DC), two selected for 21 yr for increased 120-d weight (HW and DH) and one selected for 19 yr for multiple births (T). Ewes were synchronized in late July or early August at the start of the normal breeding season with intravaginal pessaries impregnated with 60 mg methylacetoxyprogesterone and examined at first and second estrus. Ovulation had occurred in both cycles in 327 (89%) and 177 (85%) of the mature and yearling ewes, respectively. Overall mean numbers of corpora lutea at first and second estrus were 1.42 and 1.63, respectively for ewes 2 yr and over and 1.20 and 1.44 for yearlings, indicating an effect of synchronizing treatment, season, flushing, or a combination of these. Among mature ewes, ovulation rate was higher (P less than .05) in DH (+.20), HW (+.19) and T (+.16) than in controls at first estrus, and in HW (+.29) and T (+.21) but not DH (-.04) at second estrus. Among yearlings, differences were significant only at second estrus (HW, +.40; T, +.35) and again not for DH (+.08). The failure of line DH to increase in ovulation rate from first to second estrus as did other lines was transmitted to linecross progeny. Body weight within line affected ovulation rate significantly, with a greater effect at second estrus, in both age groups. Adjustment for body weight removed the difference between HW and controls but not between T and controls. Repeatability of corpora lutea count was .27 and .25 for mature and yearling ewes, respectively.
对366只2岁及以上的母羊和85只来自基础群体的5个塔吉斯品系的周岁母羊，在两个连续周期通过腹腔镜检查测量排卵率；还纳入了53只周岁杂交母羊。这些品系包括两个未选择的对照品系（HCl和DC），两个为增加120日龄体重而选择了21年的品系（HW和DH），以及一个为多胎选择了19年的品系（T）。在正常繁殖季节开始时，于7月下旬或8月初，用含60毫克甲基乙酰氧基孕酮的阴道栓剂使母羊同期发情，并在第一次和第二次发情时进行检查。成熟母羊和周岁母羊中，分别有327只（89%）和177只（85%）在两个周期均发生了排卵。2岁及以上母羊在第一次和第二次发情时黄体的总体平均数分别为1.42和1.63，周岁母羊分别为1.20和1.44，表明同期发情处理、季节、催情或这些因素的组合有影响。在成熟母羊中，第一次发情时，DH（增加0.20）、HW（增加0.19）和T（增加0.16）的排卵率高于对照组（P<0.05），第二次发情时，HW（增加0.29）和T（增加0.21）高于对照组，但DH（减少0.04）不高于对照组。在周岁母羊中，差异仅在第二次发情时显著（HW增加0.40；T增加0.35），DH（增加0.08）不显著。与其他品系不同，DH品系从第一次发情到第二次发情排卵率未增加，这一现象遗传给了杂交后代。两个年龄组内，品系内体重均显著影响排卵率，在第二次发情时影响更大。对体重进行校正后，消除了HW与对照组之间的差异，但未消除T与对照组之间的差异。成熟母羊和周岁母羊黄体计数的重复性分别为0.27和0.25。
