Fouilloux Marie-Noëlle, Clément Virginie, Laloë Denis
Institut de l'Elevage, Station de génétique quantitative et appliquée, INRA, 78352 Jouy-en-Josas, France.
Genet Sel Evol. 2008 Mar-Apr;40(2):145-59. doi: 10.1186/1297-9686-40-2-145. Epub 2008 Feb 27.
A procedure to measure connectedness among groups in large-sized genetic evaluations is presented. It consists of two steps: (a) computing coefficients of determination (CD) of comparisons among groups of animals; and (b) building sets of connected groups. The CD of comparisons were estimated using a sampling-based method that estimates empirical variances of true and predicted breeding values from a simulated n-sample. A clustering method that may handle a large number of comparisons and build compact clusters of connected groups was developed. An aggregation criterion (Caco) that reflects the level of connectedness of each herd was computed. This procedure was validated using a small beef data set. It was applied to the French genetic evaluation of the beef breed with most records and to the genetic evaluation of goats. Caco was more related to the type of service of sires used in the herds than to herd size. It was very sensitive to the percentage of missing sires. Disconnected herds were reliably identified by low values of Caco. In France, this procedure is the reference method for evaluating connectedness among the herds involved in on-farm genetic evaluation of beef cattle (IBOVAL) since 2002 and for genetic evaluation of goats from 2007 onwards.
本文提出了一种用于测量大型遗传评估中群体间连通性的方法。该方法包括两个步骤：（a）计算动物群体间比较的决定系数（CD）；（b）构建连通群体集。比较的CD使用基于抽样的方法进行估计，该方法从模拟的n样本中估计真实育种值和预测育种值的经验方差。开发了一种聚类方法，该方法可以处理大量比较并构建连通群体的紧凑聚类。计算了反映每个畜群连通水平的聚合标准（Caco）。该方法使用一个小型牛肉数据集进行了验证。它被应用于拥有最多记录的肉牛品种的法国遗传评估以及山羊的遗传评估。Caco与畜群中使用的种公牛的服务类型的相关性高于与畜群规模的相关性。它对缺失种公牛的百分比非常敏感。通过Caco的低值可以可靠地识别不连通的畜群。在法国，自2002年以来，该方法是评估参与肉牛农场遗传评估（IBOVAL）的畜群之间连通性的参考方法，自2007年起是山羊遗传评估的参考方法。
