Sartori Roberto, Bastos Michele R, Wiltbank Milo C
Department of Animal Science, University of São Paulo (USP), Piracicaba, SP 13418-900, Brazil.
Reprod Fertil Dev. 2010;22(1):151-8. doi: 10.1071/RD09221.
Data on fertilisation and embryo quality in dairy cattle are presented and the main factors responsible for the low fertility of single-ovulating lactating cows and embryo yield in superovulated dairy cattle are highlighted. During the past 50 years, the fertility in high-producing lactating dairy cattle has decreased as milk production increased. Recent data show conception rates to first service to be approximately 32% in lactating cows, whereas in heifers it has remained above 50%. Fertilisation does not seem to be the principal factor responsible for the low fertility in single-ovulating cows, because it has remained above 80%. Conversely, early embryonic development is impaired in high-producing dairy cows, as observed by most embryonic losses occurring during the first week after fertilisation. However, in superovulated dairy cattle, although fertilisation failure is more pronounced, averaging approximately 45%, the percentage of fertilised embryos viable at 1 week is quite high (>70%). Among the multifactorial causes of low fertility in lactating dairy cows, high feed intake associated with low concentrations of circulating steroids may contribute substantially to reduced embryo quality. Fertilisation failure in superovulated cattle may be a consequence of inappropriate gamete transport due to hormonal imbalances.
本文介绍了奶牛受精和胚胎质量的数据，并着重指出了单排卵泌乳奶牛繁殖力低以及超排奶牛胚胎产量低的主要影响因素。在过去50年中，随着牛奶产量的增加，高产泌乳奶牛的繁殖力有所下降。最新数据显示，泌乳奶牛首次输精的受胎率约为32%，而小母牛的受胎率则保持在50%以上。受精似乎不是单排卵奶牛繁殖力低的主要因素，因为其受精率仍高于80%。相反地，高产奶牛的早期胚胎发育受到损害，这可通过受精后第一周内发生的大多数胚胎损失观察到。然而，在超排奶牛中，尽管受精失败更为明显，平均约为45%，但受精后1周存活的胚胎百分比相当高（>70%）。在泌乳奶牛繁殖力低的多因素原因中，高采食量与循环类固醇浓度低可能在很大程度上导致胚胎质量下降。超排奶牛的受精失败可能是由于激素失衡导致配子运输不当的结果。
