Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Bünteweg 17p, 30559 Hannover, Germany.
J Anim Sci. 2012 Apr;90(4):1088-96. doi: 10.2527/jas.2011-3855. Epub 2011 Oct 7.
Breeding standards of most dog breeds specify tolerable ranges of certain conformation traits. In the German shepherd dog (GSD), current means for withers height (WH) and BW are close to the upper breed limits. Therefore, strategies to avoid a further increase in size and to maximize the proportion of dogs fitting the breeding standard with respect to WH and BW should be compared. Body measurements were available for 14,416 male and 21,612 female GSD from 26,155 litters. Withers height and body mass index (BMI; i.e., BW/WH(2)) were considered direct selection traits. Using information on 17,154 GSD from litters with at least 2 dogs with conformation data, we defined within-litter variances of WH (vWH) and BMI (vBMI) as traits to select for the conformational homogeneity of litters. Officially recorded scores for canine hip dysplasia (CHD) of all dogs were used to monitor possible side effects of conformation selection on CHD. Genetic parameters were estimated multivariately in linear animal models by using Gibbs sampling. Heritabilities ranged between 0.19 and 0.34 for all traits, and additive genetic correlations between WH and vWH were -0.11 and those between BMI and vBMI were 0.11. The expected selection response was studied using the relative breeding values (RBV) of parents, assuming exclusion of sires, dams, or both with RBV larger than 120 and comparing means of WH, BMI, and CHD scores between offspring of all and selected parents. Concurrent selection for small WH and vWH was found to reduce the mean WH in males and females most efficiently while having little effect on CHD distributions. Multiple-trait selection for WH, vWH, BMI, and vBMI was hindered by the negative genetic correlations between the traits, and it tended to interfere with improvement of CHD status. Use of the RBV for WH and vWH for conformation selection is therefore recommended to maximize breeding success with regard to conformation and conformational homogeneity in the GSD.
大多数犬种的繁育标准都规定了某些结构特征的可接受范围。在德国牧羊犬中，目前用于衡量肩高（WH）和 BW 的方法已经接近品种上限。因此，应该比较避免进一步增加体型和使符合 WH 和 BW 繁育标准的犬只比例最大化的策略。我们获得了 26155 窝 14416 只雄性和 21612 只雌性德国牧羊犬的身体测量数据。肩高和身体质量指数（BMI，即 BW/WH(2)）被视为直接选择特征。利用至少有 2 只具有体型数据的幼犬的 17154 只德国牧羊犬的数据，我们将 WH（vWH）和 BMI（vBMI）的窝内方差定义为选择幼犬体型一致性的特征。所有犬只的犬髋关节发育不良（CHD）的官方记录评分被用于监测体型选择对 CHD 的可能副作用。通过使用 Gibbs 抽样，在线性动物模型中对多变量进行遗传参数估计。所有性状的遗传力在 0.19 到 0.34 之间，WH 和 vWH 之间的加性遗传相关为-0.11，而 BMI 和 vBMI 之间的遗传相关为 0.11。通过使用父母的相对繁殖值（RBV），假设排除 RBV 大于 120 的公犬、母犬或两者，并比较所有和选择的父母后代的 WH、BMI 和 CHD 评分的平均值，研究了预期的选择反应。同时选择较小的 WH 和 vWH 可以最有效地降低雄性和雌性德国牧羊犬的平均 WH，而对 CHD 分布的影响很小。由于性状之间的负遗传相关，对 WH、vWH、BMI 和 vBMI 的多性状选择受到阻碍，并且往往会干扰 CHD 状况的改善。因此，建议使用 RBV 对 WH 和 vWH 进行体型选择，以最大限度地提高德国牧羊犬在体型和体型一致性方面的繁殖成功率。
