In the management of dairy cattle breeds, two recent trends have arisen that pose potential threats to genetic diversity: the use of reproductive technologies (RT) and a reduction in the number of bulls in breeding schemes. The expected outcome of these changes, in terms of both genetic gain and genetic diversity, is not trivial to predict. Here, we simulated 15 breeding schemes similar to those carried out in large French dairy cattle breeds; breeding schemes differed with respect to their dimensions, the intensity of RT use, and the type of RT involved. We found that intensive use of RT resulted in improved genetic gain, but deteriorated genetic diversity. Specifically, a reduction in the interval between generations through the use of ovum pick-up and in vitro fertilization (OPU-IVF) resulted in a large increase in the inbreeding rate both per year and per generation, suggesting that OPU-IVF could have severe adverse effects on genetic diversity. To achieve a given level of genetic gain, the scenarios that best maintained genetic diversity were those with a higher number of sires/bulls and a medium intensity of RT use or those with a higher number of female donors to compensate for the increased intensity of RT.

中文翻译：

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繁殖技术的大量使用和育种计划的缩小使乳牛品种的遗传多样性面临风险

在奶牛品种的管理中，出现了两个最近的趋势，这些趋势对遗传多样性构成了潜在的威胁：繁殖技术的使用和繁殖计划中公牛数量的减少。就遗传增益和遗传多样性而言，这些变化的预期结果并非难以预测。在这里，我们模拟了15种与法国大型奶牛品种相似的育种方案。繁殖计划的规模，RT使用强度和所涉及的RT类型不同。我们发现大量使用RT可以提高遗传增益，但会破坏遗传多样性。特别，通过使用卵子采摘和体外受精（OPU-IVF）减少了世代间隔，导致每年和每代的近交率大大增加，这表明OPU-IVF可能产生严重的不良影响关于遗传多样性。为了达到既定水平的遗传增益，最能维持遗传多样性的场景是那些具有较高父系/种数和中等强度RT使用的场景，或具有较高数量女性供体以弥补增强RT强度的场景。 。