Faculty of Land and Animal Resources, The Agricultural University of Iceland, 311 Borgarnes, Iceland.
J Anim Breed Genet. 2011 Apr;128(2):124-32. doi: 10.1111/j.1439-0388.2010.00902.x. Epub 2011 Jan 12.
Genetic evaluation of Icelandic horses is currently based on results from breeding field tests where riding ability and conformation of the horses are evaluated over the course of 1-2 days. Only a small part of registered horses attend these field tests, and it can be assumed that these are not a random sample of the population. In this study, the trait test status was introduced, describing whether a horse was assessed in a breeding field test. This trait was analysed to find out whether it has a genetic variation and how it correlates genetically to other traits in the breeding goal. Breeding field test data included 39,443 mares born in Iceland in 1990-2001, of which 7431 were assessed in the period 1994-2007. The trait was defined in relation to age, gender and stud of horses. Variance and covariance components were estimated using the Markov Chain Monte Carlo method by applying the Gibbs sampler procedure in the DMU program. Three multivariate analyses were performed where the test status trait was analysed with breeding field test traits. Animal models and sire models were applied. Based on estimated heritabilities (0.51-0.67) and genetic correlations (0.00-0.87), the test status trait showed significant genetic variation and was strongly correlated to some traits. The test status trait reflects preselection in the breeding field test traits and should be included in the genetic evaluation to enhance the procedure, reduce selection bias and increase accuracy of the estimation.
冰岛马的遗传评估目前基于繁殖场测试的结果，这些测试在 1-2 天内评估马的骑行能力和外形。只有一小部分注册马参加这些场测试，可以假设这些马不是群体的随机样本。在这项研究中，引入了性状测试状态，描述马是否在繁殖场测试中进行了评估。对该性状进行了分析，以确定其是否存在遗传变异，以及其与繁殖目标中的其他性状在遗传上的相关性。繁殖场测试数据包括 1990-2001 年在冰岛出生的 39,443 匹母马，其中 7431 匹在 1994-2007 年期间进行了评估。该性状是根据马的年龄、性别和种马定义的。使用 Markov Chain Monte Carlo 方法，通过在 DMU 程序中应用 Gibbs 抽样程序，估计方差和协方差分量。进行了三次多元分析，其中将测试状态性状与繁殖场测试性状进行了分析。应用了动物模型和种马模型。基于估计的遗传力（0.51-0.67）和遗传相关系数（0.00-0.87），测试状态性状显示出显著的遗传变异，并且与一些性状高度相关。测试状态性状反映了繁殖场测试性状的预选择，应包含在遗传评估中，以增强程序、减少选择偏差并提高估计的准确性。
