Aurich C, Budik S
Centre for Artificial Insemination and Embryo Transfer, Vetmeduni Vienna, Austria.
Reprod Domest Anim. 2015 Apr;50(2):299-303. doi: 10.1111/rda.12490. Epub 2015 Jan 27.
Although the horse is a seasonal breeding species, a considerable number of mares continue to cycle throughout autumn and winter. Slower equine embryo growth during the non-breeding season has been hypothesized, and because smaller embryo size is beneficial for cryopreservation, embryo collection outside the breeding season could be an interesting approach for the production of frozen horse embryos. In the present retrospective study, we have therefore analysed embryo recovery rates and conceptus size in mares (n = 30) throughout the year. Conceptus diameter was either size determined after collection with a microscopic scale (day 7-10 after ovulation) or determined by transrectal ultrasound immediately before collection (day 11-14 after ovulation). In 19 of the 30 mares (63%), ovulatory cycles were detected throughout the year. A total of 352 embryo collections with a mean recovery rate of 64.2% were performed and not affected by season. The size was analysed in a total of 165 conceptuses. Conceptus diameter significantly increased (p < 0.001) with day of pregnancy (e.g. day 7: 0.3 ± 0.04, day 10: 4.1 ± 0.2, day 12: 10.1 ± 0.5, day 14: 17.4 ± 0.9 mm), but was not influenced by season. In conclusion, successful embryo collection is possible throughout the year in spontaneously cyclic mares. Under these conditions, neither collection rates nor embryo growth appeared to be affected by season.
尽管马是季节性繁殖动物，但仍有相当数量的母马在整个秋冬季节持续发情。有假设认为，在非繁殖季节马胚胎的生长速度较慢，而且由于较小的胚胎尺寸有利于冷冻保存，因此在繁殖季节之外采集胚胎可能是生产冷冻马胚胎的一种有趣方法。在本回顾性研究中，我们分析了全年30匹母马的胚胎回收率和孕体大小。孕体直径要么是在采集后用显微镜测量确定的大小（排卵后第7 - 10天），要么是在采集前通过经直肠超声确定的（排卵后第11 - 14天）。在30匹母马中的19匹（63%）全年都检测到了排卵周期。总共进行了352次胚胎采集，平均回收率为64.2%，且不受季节影响。总共对165个孕体进行了大小分析。孕体直径随怀孕天数显著增加（p < 0.001）（例如，第7天：0.3 ± 0.04，第10天：4.1 ± 0.2，第12天：10.1 ± 0.5，第14天：17.4 ± 0.9毫米），但不受季节影响。总之，对于自然发情的母马，全年都可以成功采集胚胎。在这些条件下，采集率和胚胎生长似乎都不受季节影响。
