Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada; Canadian Dairy Network, Guelph, ON, N1K 1E5, Canada.
Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
J Dairy Sci. 2019 Apr;102(4):3722-3734. doi: 10.3168/jds.2018-15470. Epub 2019 Feb 1.
In dairy production, high fertility contributes to herd profitability by achieving greater production and maintaining short calving intervals. Improved management practices and genetic selection have contributed to reversing negative trends in dairy cow fertility, but further progress is still required. Phenotypes included in current genetic evaluations are largely interval and binary traits calculated from insemination and calving date records. Several indicator traits such as calving, health, variation in body condition score, and longevity traits also apply to genetic improvement of fertility. Several fertility traits are included in the selection indices of many countries, but for improved selection, the development of novel phenotypes that more closely describe the physiology of reproduction and limit management bias could be more effective. Progesterone-based phenotypes can be determined from milk samples to describe the heritable interval from calving to corpus luteum activity, as well as additional measures of cow cyclicity. A fundamental component of artificial insemination practices is the observation of estrus. Novel phenotypes collected on estrous activity could be used to select for cows clearly displaying heat, as those cows are more likely to be inseminated at the right time and therefore have greater fertility performance. On-farm technologies, including in-line milk testing and activity monitors, may allow for phenotyping novel traits on large numbers of animals. Additionally, selection for improved fertility using traditional traits could benefit from refined and accurate recording and implementation of parameters such as pregnancy confirmation and reproductive management strategy, to differentiate embryonic or fetal loss, and to ensure selection for reproductive capability without producer intervention. Opportunities exist to achieve genetic improvement of reproductive efficiency in cattle using novel phenotypes, which is required for long-term sustainability of the dairy cattle population and industry.
在奶牛生产中，高繁殖力通过提高产量和保持较短的产犊间隔来提高牛群的盈利能力。改进的管理实践和遗传选择有助于扭转奶牛繁殖力的负面趋势，但仍需要进一步的进展。目前遗传评估中包含的表型主要是从配种和产犊日期记录中计算得出的间隔和二元性状。一些指示性状，如产犊、健康、体况评分变化和寿命性状，也适用于繁殖力的遗传改良。一些繁殖力性状被列入了许多国家的选择指数中，但为了更好的选择，开发更能准确描述生殖生理学和限制管理偏差的新表型可能会更有效。基于孕酮的表型可以从牛奶样本中确定，以描述从产犊到黄体活动的可遗传间隔，以及牛周期性的其他测量。人工授精实践的一个基本组成部分是观察发情。在发情活动中收集的新表型可用于选择明显发情的奶牛，因为这些奶牛更有可能在正确的时间授精，因此具有更高的繁殖性能。农场技术，包括在线牛奶测试和活动监测器，可能允许对大量动物进行新型表型的表型分析。此外，使用传统性状选择改进的繁殖力也可以受益于对参数的精细和准确记录和实施，例如妊娠确认和生殖管理策略，以区分胚胎或胎儿损失，并确保选择具有生殖能力而无需生产者干预。利用新型表型实现牛繁殖效率的遗传改良是可行的，这是奶牛种群和产业长期可持续性所必需的。
