Civil Veterinary Hospital, Mahatam Nagar, Fazilka, Punjab, India.
Theriogenology. 2010 Jul 1;74(1):90-9. doi: 10.1016/j.theriogenology.2010.01.018. Epub 2010 Mar 6.
Decreased reproductive performance due to summer stress is a well known phenomenon in farm livestock. Whether this occurs in the mare and specifically how this might affect postpartum reproductive activity and performance, especially at Foal Heat (FH), is unknown. This study, therefore, aims to investigate this and the factors that might affect postpartum reproductive activity. Reproductive records of 228 Thoroughbred mares (694 mare years) bred in subtropical north-western India were retrospectively analysed. Overt oestrous activity occurred within 21 d postpartum in 92.94% (645/694) of mares. Significantly (p<0.001) more April foaling mares (97.37%, 185/190) expressed postpartum oestrous activity than those foaling in January (83.61%; 51/61) and February (88.49; 123/139). Similarly significantly (p<0.01) fewer multiparous mares failed to demonstrate oestrous activity than primiparous mares (6.12% vs.15.07%; 38/621 vs. 11/73, respectively). 190 of these 694 mares were additionally monitored to confirm ovulation; in these mares onset of FH (oestrus plus confirmed ovulation) occurred 8.42+/-0.17 d and first ovulation 13.64+/-0.20 d postpartum. Month, stud farm, year, and parity did not affect interval from parturition to FH onset or to first ovulation; or FH onset to ovulation. In FH bred mares Day 16 pregnancy rate and overall foaling rate were 53.76% (100/186) and 46.24% (86/186) respectively and were similar to those of mares bred later postpartum. FH pregnancy rates were not affected by stud, season, month, year, number of matings, or day of ovulation but were significantly (p<0.008) lowered by increasing mare age. Significantly (p<0.01) lower Day 16 pregnancy rates were observed in uterine treated mares compared to untreated mares (31.09% vs. 57.96%; 9/29 vs. 91/157, respectively), this difference was not evident during the rest of pregnancy. In conclusion, postpartum reproductive and ovarian activity appears to be affected by environment, i.e., delayed in subtropical kept Thoroughbred mares compared to those kept in temperate climates. However, resulting reproductive performance at FH and the factors affecting postpartum reproductive activity are similar.
由于夏季应激导致繁殖性能下降是家畜养殖中众所周知的现象。这种情况是否会在母马中发生，特别是它如何影响产后繁殖活动和性能，尤其是在发情期（FH），目前尚不清楚。因此，本研究旨在调查这一现象以及可能影响产后繁殖活动的因素。本研究回顾性分析了 228 匹在印度西北部亚热带地区养殖的纯血马（694 个母马年）的繁殖记录。在产后 21 天内，92.94%（645/694）的母马出现明显的发情活动。发情活动明显（p<0.001）多于 4 月份产驹的母马（97.37%，185/190），而 1 月份（83.61%；51/61）和 2 月份（88.49%；123/139）产驹的母马较少。同样显著（p<0.01）的是，多胎母马未表现发情活动的比例低于初产母马（6.12%比 15.07%；38/621 比 11/73）。在这 694 匹母马中，有 190 匹被进一步监测以确认排卵；在这些母马中，发情期（发情加上确认排卵）发生在产后 8.42+/-0.17 天，第一次排卵发生在产后 13.64+/-0.20 天。月份、饲养场、年份和胎次均不影响从分娩到发情期开始或到第一次排卵的间隔时间；或发情期开始到排卵的间隔时间。在发情期配种的母马中，第 16 天的妊娠率和总产驹率分别为 53.76%（100/186）和 46.24%（86/186），与产后较晚配种的母马相似。发情期妊娠率不受饲养场、季节、月份、年份、配种次数或排卵日的影响，但母马年龄的增加显著（p<0.008）降低了发情期妊娠率。与未处理的母马相比，子宫处理的母马在第 16 天的妊娠率显著（p<0.01）降低（31.09%比 57.96%；9/29 比 91/157），但在妊娠后期这一差异并不明显。综上所述，产后繁殖和卵巢活动似乎受到环境的影响，即与温带气候相比，亚热带饲养的纯血马繁殖活动延迟。然而，发情期的繁殖性能和影响产后繁殖活动的因素是相似的。
