Genetic variability and trans-generational effects on production in dairy cattle

在过去的20年里，哺乳动物中发现了一个新现象，即母亲的代谢环境对后代表型的影响。虽然这一现象最初是在人类的流行病学调查中观察到的（巴克假说），但它已扩展到迄今所研究的所有哺乳动物，包括羊和牛。母亲和父亲的代谢状况都可以留下功能性的跨代效应，这将影响下一代的健康状况和生产，并在某些情况下影响后代。除了荷兰饥荒之外，最好的例子是用高脂肪饮食来喂养老鼠，即使是正常饮食，老鼠也会肥胖。在牛中，研究表明，在受孕前开始的饲料限制对女儿的卵泡计数有直接影响。这一点很重要，因为卵泡计数与奶牛和人类的生育能力有直接联系。因此，可以假设，在高泌乳期的奶牛授精通常与负能量平衡有关，可能会使子代卵巢储备减少，生育能力降低，产量降低。目前，这种跨代影响在加拿大奶牛中的程度尚不清楚。建议使用生产和饲料的牛奶记录数据以及健康事件数据来估计这种对生产性状的跨代影响，从而确定是否需要在遗传评估系统中考虑这些影响，以及是否可以将它们纳入农场管理咨询。

A new phenomenon has been discovered in mammals over the last 2 decades, the influence of the mother's metabolic environment on the phenotype of the offspring. Although this has been initially observed in epidemiological survey in humans (Barker Hypothesis) it has been extended to all mammals studied so far including sheep and cows. The metabolic condition of both the mother and the father can leave functional trans-generational effects that will affect the health status and production of the following generation and in some conditions of the subsequent generation. The best example outside of the Dutch famine is the fat diet applied to mice which program obesity even on a normal diet. In bovines, it has been shown that feed restriction starting before conception has a direct influence on follicle count in the daughter. This is important since follicle count has a direct link with fertility in cows and in humans. Therefore, it can be postulated that the insemination of cows during a period of high lactation often associated with a negative energy balance may have programmed the daughter with a diminished ovarian reserve and lower fertility and lower production. Currently the magnitudes of such trans-generational effects in dairy cattle in Canada are not known are. It is proposed to use milk recording data on production and feed, together with health event data to estimate such trans-generational effects on production traits and hence determine whether these need to be accounted for in genetic evaluation systems and whether they could be incorporated into farm-management advising.