Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
J Dairy Sci. 2010 Dec;93(12):5977-86. doi: 10.3168/jds.2010-3437.
The need to implement a method that can handle multiple traits per country in international genetic evaluations is evident. Today, many countries have implemented multiple-trait national genetic evaluations and they may expect to have their traits simultaneously analyzed in international genetic evaluations. Traits from the same country are residually correlated and the method currently in use, single-trait multiple across-country evaluation (ST-MACE), cannot handle nonzero residual correlations. Therefore, multiple-trait, multiple across-country evaluation (MT-MACE) was proposed to handle several traits from the same country simultaneously. To test the robustness of MT-MACE on real data, female fertility was chosen as a complex trait with low heritability. Data from 7 Holstein populations, 3 with 2 traits and 4 with 1 trait, were used. The differences in the estimated genetic correlations by MT-MACE and the single ST-MACE analysis (average absolute deviation of 0.064) were due to the bias of considering several traits from the same country in the ST-MACE analysis. However, the differences between the estimated genetic correlations by MT-MACE and multiple ST-MACE analyses avoiding more than one trait per country in each analysis (average absolute deviation of 0.066) were due to the lack of analysis of the correlated traits from the same country together and using the reported within-country genetic correlations. Applying MT-MACE resulted in reliability gain in international genetic evaluations, which was different from trait to trait and from bull to bull. The average reliability gain by MT-MACE over ST-MACE was 3.0 points for domestic bulls and 6.3 points for foreign bulls. Even countries with 1 trait benefited from the joint analysis of traits from the 2-trait countries. Another superiority of MT-MACE over ST-MACE is that the bulls that do not have national genetic evaluation for some traits from multiple trait countries will receive international genetic evaluations for those traits. Rank correlations were high between ST-MACE and MT-MACE when considering all bulls. However, the situation was different for the top 100 bulls. Simultaneous analysis of traits from the same country affected bull ranks, especially for top 100 bulls. Multi-trait MACE is a recommendable and robust method for international genetic evaluations and is appropriate for handling multiple traits per country, which can increase the reliability of international genetic evaluations.
显然，需要实施一种能够处理每个国家多个性状的方法。如今，许多国家已经实施了多性状国家遗传评估，并且可能期望在国际遗传评估中同时分析它们的性状。来自同一国家的性状具有残差相关性，而目前使用的方法，即单性状跨国多次评估（ST-MACE），不能处理非零残差相关性。因此，提出了多性状、跨国多次评估（MT-MACE）来同时处理来自同一国家的多个性状。为了在真实数据上测试 MT-MACE 的稳健性，选择了低遗传力的雌性生育力作为复杂性状。使用了来自 7 个荷斯坦种群的数据，其中 3 个种群具有 2 个性状，4 个种群具有 1 个性状。MT-MACE 和单 ST-MACE 分析估计的遗传相关性之间的差异（平均绝对偏差为 0.064）是由于在 ST-MACE 分析中考虑了来自同一国家的多个性状而产生的偏差。然而，MT-MACE 和避免在每个分析中每个国家超过一个性状的多个 ST-MACE 分析之间估计的遗传相关性之间的差异（平均绝对偏差为 0.066）是由于缺乏对来自同一国家的相关性状的分析以及使用报告的国内遗传相关性。应用 MT-MACE 导致国际遗传评估中的可靠性提高，这因性状和公牛而异。MT-MACE 相对于 ST-MACE 的平均可靠性增益为国内公牛 3.0 点，国外公牛 6.3 点。即使是只有一个性状的国家也受益于来自两个性状国家的性状联合分析。MT-MACE 相对于 ST-MACE 的另一个优势是，对于没有来自多性状国家的某些性状的国家遗传评估的公牛，将为这些性状提供国际遗传评估。考虑到所有公牛时，ST-MACE 和 MT-MACE 之间的秩相关度很高。然而，对于前 100 名公牛，情况则不同。同一国家性状的同时分析会影响公牛的等级，特别是对于前 100 名公牛。多性状 MACE 是一种可推荐的稳健的国际遗传评估方法，适用于处理每个国家的多个性状，可以提高国际遗传评估的可靠性。
