Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL, 61802, USA.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32608, USA; Department of Animal Medicine, Faculty of Veterinary Medicine, Benha University, Moshtohor-Toukh, Kalyobiya, 13736, Egypt.
Theriogenology. 2022 Jun;185:140-148. doi: 10.1016/j.theriogenology.2022.03.003. Epub 2022 Mar 15.
This study aimed to assess the ovulatory response of deslorelin acetate during the fall and the response to PGF2α 8 d post-ovulation. One hundred estrous cycles from 22 mares kept in 40° latitude were evaluated. Mares were checked by transrectal ultrasonography until a preovulatory follicle was detected and ovulation induced with deslorelin acetate. Ovulation was confirmed by ultrasonography performed at 24, 36 h post-induction and then repeated at 2-h intervals post-induction. Serum progesterone concentrations and luteal tissue area were determined daily to assess CL function. A dose of PGF2α was administered 8 d post-ovulation and interval to the subsequent ovulation was observed; each mare completed up to five cycles. The effects of local climate on endpoints were analyzed. Cycles were grouped as early (Sept 13, 2020-Oct 31, 2020; n = 55; 22 mares) and late fall (Nov 1, 2020-Dec 31, 2020; n = 45; 20 mares) based on the date of induction. The overall number of cycles with ovulations between 24 and 48 h was 90%. The number of multiple ovulations were similar between early (n = 5) and late (n = 4) fall (P = 0.87). There were no differences in deemed spontaneous ovulations occurring before 24 h between early (n = 6) and late (n = 2) fall (P = 0.29). Two failures to respond to deslorelin by 48 h were recorded in early fall and none in the late fall. The interval from induction to ovulation was similar in early (40.6 ± 0.4 h) and late (41.2 ± 0.5 h) fall (P = 0.55). The percentage of mares ovulating between 36 and 48 h post-deslorelin did not vary between early and late fall (91 vs. 95%, P = 0.21), as did not for ovulation occurring between 38 h and 44 h (62 vs. 60%, P = 0.69). Edema scores varied with time relative to ovulation (P < 0.001) and were lower in late fall (P = 0.01). Progesterone concentrations varied with time (P < 0.001) but did not differ between early and late fall (P = 0.73) and correlated weakly with the luteal area (r = 0.13; P = 0.031). Follicles <35 mm at the PGF2α had a shorter interval to the next ovulation than follicles ≥ 35 mm (9.2 ± 0.5 d vs. 10.6 ± 1.2 d) (P = 0.03). Lower temperature was associated with a smaller follicle size at induction (P = 0.0021) and ovulation (P = 0.009) and lower relative humidity was associated with a larger follicle size at ovulation (P = 0.032). In conclusion, cycling mares displayed a highly efficacious response to deslorelin acetate and apparently normal luteal function during the fall, despite lower edema scores in late fall.
本研究旨在评估秋季去势隆（deslorelin acetate）对排卵的反应，以及排卵后 8 天对 PGF2α的反应。对来自北纬 40 度地区的 22 匹母马的 100 个发情周期进行了评估。通过直肠超声检查直到检测到一个预排卵卵泡，然后用去势隆诱导排卵。排卵通过诱导后 24、36 小时进行的超声检查确认，然后每隔 2 小时重复一次。为了评估黄体功能，每天测定血清孕酮浓度和黄体组织面积。排卵后 8 天给予 PGF2α，并观察到随后的排卵间隔；每匹马完成了最多五个周期。分析了局部气候对终点的影响。根据诱导日期将周期分为早秋（2020 年 9 月 13 日至 10 月 31 日；n=55；22 匹母马）和晚秋（2020 年 11 月 1 日至 12 月 31 日；n=45；20 匹母马）。在 24 至 48 小时之间排卵的周期总数为 90%。早期（n=5）和晚期（n=4）秋季的多排卵次数相似（P=0.87）。在 24 小时前自发排卵的数量在早期（n=6）和晚期（n=2）秋季之间没有差异（P=0.29）。在早期秋季有 2 例对去势隆没有反应，而在晚期秋季没有。从诱导到排卵的时间在早期（40.6±0.4 小时）和晚期（41.2±0.5 小时）秋季相似（P=0.55）。排卵后 36 至 48 小时之间排卵的母马百分比在早期和晚期秋季没有差异（91%对 95%，P=0.21），排卵后 38 至 44 小时之间排卵的百分比也没有差异（62%对 60%，P=0.69）。肿胀评分随时间相对于排卵而变化（P<0.001），并且在秋季晚期较低（P=0.01）。孕酮浓度随时间变化（P<0.001），但在早秋和晚秋之间没有差异（P=0.73），与黄体面积呈弱相关（r=0.13；P=0.031）。PGF2α 时直径<35mm 的卵泡与直径≥35mm 的卵泡相比，下一次排卵的间隔时间更短（9.2±0.5 天比 10.6±1.2 天）（P=0.03）。较低的温度与诱导时（P=0.0021）和排卵时（P=0.009）的卵泡较小以及相对湿度较高与排卵时的卵泡较大有关（P=0.032）。总之，尽管在秋季晚期肿胀评分较低，但发情母马对去势隆的反应非常有效，黄体功能似乎正常。
