Review: Understanding the causes of variation in reproductive wastage among bulls
Review: Understanding the causes of variation in reproductive wastage among bulls
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DOI：
10.1017/s1751731118000964
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发表时间：
2018-06-01
期刊：
影响因子：
3.6
通讯作者：
Lonergan, P.
中科院分区：
文献类型：
--
作者：
Fair, S.;Lonergan, P.
在精液被释放到田间之前预测公牛生育能力的能力一直是动物育种业的长期目标。然而，最近乳制品行业向密集使用基因组选择的年轻公牛的转变增加了其紧迫性。这种公牛，这往往是在最高的需求，往往只集中使用一个赛季，因此有有限的时间来跟踪其领域的生育能力。一个更紧迫的问题是，它们每次射精产生的精子比成熟公牛少，因此需要将每根吸管的精子数量减少到所需的最低限度，而不伴随生育力的降低。然而，由于个体公牛在达到其最大生育力所需的最低精子数量方面存在差异，因此如果没有广泛的实地测试，目前无法实现这一目标。虽然体外精液质量测试或测试组合可以准确和一致地确定公牛的生育能力和所需的最佳精子数量，但在精液评估方面代表了“圣杯”，但迄今为止尚未实现。了解公牛生育力变化的根本原因是实现这一目标的关键先决条件。在这篇综述中，我们考虑公鹿受胎率估计的可靠性，然后考虑在沿着怀孕建立轴公牛之间发生的生殖损失的变化。我们讨论了这些精子功能缺陷的病因，并提出了未来调查的途径。
The ability to predict the fertility of bulls before semen is released into the field has been a long-term objective of the animal breeding industry. However, the recent shift in the dairy industry towards the intensive use of young genomically selected bulls has increased its urgency. Such bulls, which are often in the highest demand, are frequently only used intensively for one season and consequently there is limited time to track their field fertility. A more pressing issue is that they produce fewer sperm per ejaculate than mature bulls and therefore there is a need to reduce the sperm number per straw to the minimum required without a concomitant reduction in fertility. However, as individual bulls vary in the minimum number of sperm required to achieve their maximum fertility, this cannot be currently achieved without extensive field-testing. Although an in vitro semen quality test, or combination of tests, which can accurately and consistently determine a bull's fertility and the optimum sperm number required represent the 'holy grail' in terms of semen assessment, this has not been achieved to date. Understanding the underlying causes of variation in bull fertility is a key prerequisite to achieving this goal. In this review, we consider the reliability of sire conception rate estimates and then consider where along the pregnancy establishment axis the variation in reproductive loss between bulls occurs. We discuss the aetiology of these deficiencies in sperm function and propose avenues for future investigation.