Council on Dairy Cattle Breeding, Bowie, MD 20716.
Animal Genomics and Improvement Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705.
J Dairy Sci. 2020 Jun;103(6):5354-5365. doi: 10.3168/jds.2019-17687. Epub 2020 Apr 22.
The rate at which new traits are being developed is increasing, leading to an expanding number of evaluations provided to dairy producers, especially for functional traits. This review will discuss the development and implementation of genetic evaluations for direct health traits in the United States, as well as potential future developments. Beginning in April 2018, routine official genomic evaluations for 6 direct health traits in Holsteins were made available to US producers from the Council on Dairy Cattle Breeding (Bowie, MD). Traits include resistance to milk fever, displaced abomasum, ketosis, clinical mastitis, metritis, and retained placenta. These health traits were included in net merit indices beginning in August 2018, with a total weight of approximately 2%. Previously, improvement of cow health was primarily made through changes to management practices or genetic selection on indicator traits, such as somatic cell score, productive life, or livability. Widespread genomic testing now allows for accelerated improvement of traits with low heritabilities such as health; however, phenotypes remain essential to the success of genomic evaluations. Establishment and maintenance of data pipelines is a critical component of health trait evaluations, as well as appropriate data quality control standards. Data standardization is a necessary process when multiple data sources are involved. Model refinement continues, including implementation of variance adjustments beginning with the April 2019 evaluation. Mastitis evaluations are submitted to Interbull along with somatic cell score for international validation and evaluation of udder health. Additional areas of research include evaluation of other breeds for direct health traits, use of multiple-trait models, and evaluations for additional functional traits such as calf health and feed efficiency. Future developments will require new and continued cooperation among numerous industry stakeholders. There is more information available than ever before with which to make better selection decisions; however, this also makes it increasingly important to provide accurate and unbiased information.
新特性的发展速度正在加快，这导致向奶农提供的评估数量不断增加，尤其是针对功能性特性。本文将讨论在美国开发和实施直接健康性状遗传评估的情况，以及潜在的未来发展。从 2018 年 4 月开始，美国奶业遗传委员会（马里兰州鲍伊）开始向奶农提供荷斯坦牛 6 个直接健康性状的常规官方基因组评估。这些性状包括乳热症抗性、真胃移位、酮病、临床型乳腺炎、子宫炎和胎衣不下。这些健康性状从 2018 年 8 月开始被纳入净效益指数，权重约为 2%。在此之前，奶牛健康的改善主要是通过改变管理实践或选择体细胞评分、产奶寿命或成活率等指示性状进行的。广泛的基因组测试现在可以加速改善遗传力低的性状，如健康；然而，表型对于基因组评估的成功仍然至关重要。建立和维护数据管道是健康性状评估的关键组成部分，还需要适当的数据质量控制标准。当涉及多个数据源时，数据标准化是一个必要的过程。模型不断得到完善，包括从 2019 年 4 月评估开始实施方差调整。乳腺炎评估与体细胞评分一起提交给国际动物遗传学会，以进行国际验证和乳房健康评估。其他研究领域包括评估其他品种的直接健康性状、使用多性状模型以及评估其他功能性性状，如犊牛健康和饲料效率。未来的发展将需要众多行业利益相关者之间开展新的和持续的合作。现在有比以往更多的信息可供使用，以做出更好的选择决策；然而，这也使得提供准确和无偏见的信息变得越来越重要。
