Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia.
Anim Reprod Sci. 2011 Mar;124(1-2):104-11. doi: 10.1016/j.anireprosci.2011.02.012. Epub 2011 Feb 17.
Recently, oocyte quality in sows culled for reasons unrelated to fertility was found to decline during the period of seasonal infertility. Wean-to-service interval (WSI) has also been associated with pregnancy loss in sows mated during the period of seasonal infertility. The aims of this study were to determine whether WSI and season are associated with changes in oocyte developmental competence in sows experiencing early (before Day 35 of gestation) and late (after Day 35 of gestation) pregnancy loss. Ovaries were collected in pairs from sows sourced from commercial piggeries that were culled for reasons related to infertility after being mated in summer and winter/spring. Sows were grouped according to their pregnancy loss type, their previous WSI and the presence or absence of corpora lutea (CL) on their ovaries. Oocyte developmental competence was assessed following in vitro maturation, artificial activation and parthenote development in vitro. In sows culled for early-pregnancy loss, there was a greater number of CL present on ovaries collected in spring compared to those collected in summer (11.57±3.3 vs. 9.26±0.99; P<0.05). Also, the proportion of oocytes developing to the blastocyst stage was greater in summer than in spring (55.9±5.2% vs. 31.2±6.4%; P<0.05). In sows culled for late-pregnancy loss, a greater proportion of oocytes developed to the blastocyst stage in winter compared with late-spring (64.3±7.0% vs. 34.1±6.6%; P<0.05). In addition, the blastocyst formation rate of oocytes was lower in sows that displayed a WSI≤6 days than in sows that displayed a WSI>6 days (37.8±7.3% vs. 62.2±6.9%; P<0.05). The results of the present study indicate that sows culled for pregnancy loss exhibit seasonal changes in oocyte developmental competence. The mechanism which causes WSI to be prolonged does not appear to result in reduced oocyte developmental competence. While poor oocyte quality and the mechanism that increases WSI may contribute to pregnancy loss during the seasonal infertility period, the findings suggest that these factors are not the main drivers of early and late pregnancy loss throughout the year.
最近，人们发现与繁殖力无关而被淘汰的母猪的卵母细胞质量在季节性不孕期间下降。配种-授精间隔（WSI）也与季节性不孕期间配种的母猪的妊娠丢失有关。本研究的目的是确定 WSI 和季节是否与经历早期（妊娠第 35 天之前）和晚期（妊娠第 35 天之后）妊娠丢失的母猪的卵母细胞发育能力变化有关。从夏季和冬春季节配种后因不孕而被淘汰的商业猪场收集的母猪的成对卵巢。根据母猪的妊娠丢失类型、之前的 WSI 以及卵巢上是否存在黄体（CL）对母猪进行分组。通过体外成熟、人工激活和体外孤雌激活评估卵母细胞的发育能力。在因早期妊娠丢失而被淘汰的母猪中，春季采集的卵巢上的 CL 数量明显多于夏季采集的卵巢（11.57±3.3 比 9.26±0.99；P<0.05）。此外，夏季卵母细胞发育到囊胚阶段的比例明显高于春季（55.9±5.2%比 31.2±6.4%；P<0.05）。在因晚期妊娠丢失而被淘汰的母猪中，冬季的卵母细胞发育到囊胚阶段的比例明显高于晚春（64.3±7.0%比 34.1±6.6%；P<0.05）。此外，WSI≤6 天的母猪的卵母细胞囊胚形成率低于 WSI>6 天的母猪（37.8±7.3%比 62.2±6.9%；P<0.05）。本研究的结果表明，因妊娠丢失而被淘汰的母猪的卵母细胞发育能力存在季节性变化。导致 WSI 延长的机制似乎不会导致卵母细胞发育能力下降。虽然卵母细胞质量差和增加 WSI 的机制可能导致季节性不孕期间的妊娠丢失，但研究结果表明，这些因素并不是全年导致早期和晚期妊娠丢失的主要因素。
