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Abstract：
Pedigree data of 13,339 border collie dog was collected along with canine hip dysplasia (CHD) and canine elbow dysplasia (CED) records (1352 CHD and 524 CED), and an inbreeding-purging (IP) model was created. Ancestral inbreeding coefficients were calculated by using a gene dropping simulation method with GRain 2.2 software. Cumulative logit models (CLM) for CHD and CED were fitted using a logit-link Poisson distribution and the classical (F_W), and ancestral inbreeding (F_BAL, F_KAL, and F_KAL_NEW) coefficients as linear regression coefficients. The effective population size was calculated from F_W and decreased in the examined period along with an increase of F_W; however, slight differences were found as a consequence of breeding dog imports. CHD values were lowered by the expansion of F_BAL, as the alleles had been inbred in the past. For CHD, signs of purging were obtained. There was a positive trend regarding the breeding activity (both sire and dam of the future litters should be screened and certified free from CHD and CED), as years of selection increased the frequency of alleles with favorable hip and elbow conformation. Division of the ancestral inbreeding coefficient showed that alleles that had been identical by descent (IBD) for the first time (F_KAL_NEW) had a negative effect on both traits, while F_KAL has shown favorable results for alleles IBD in past generations. Some authors had proven this phenomenon in captive populations or experimental conditions; however, no evidence of inbreeding purge has ever been described in dog populations. Despite the various breeding practices, it seems that alleles of these polygenic disorders could be successfully purged out of the population with long-term selection.
摘要：
收集了13,339只边界牧羊犬的家谱数据以及犬髋关节发育不良（CHD）和犬肘部发育不良（CED）记录（1352CHD和524CED），并创建了近亲繁殖净化（IP）模型。使用GRAIN2.2软件的基因丢弃模拟方法计算近交系数。CHD和CED的累积logit模型(CLM)使用logit-link泊松分布和经典(F_W)拟合，和祖先近亲繁殖(F_BAL，F_KAL,和F_KAL_NEW)系数作为线性回归系数。根据F_W计算有效种群规模，并在检查期间随着F_W的增加而减少；但是，由于饲养狗的进口，发现了轻微的差异。CHD值通过F_BAL的扩展而降低，因为等位基因在过去是近交的。对于CHD,获得了吹扫的迹象。关于繁殖活动有一个积极的趋势（未来垃圾的父亲和大坝都应进行筛查和认证，不含CHD和CED），随着多年的选择增加了具有良好髋关节和肘部构象的等位基因的频率。祖先近交系数的划分表明，首次通过血统（IBD）相同的等位基因（F_KAL_NEW）对两个性状都有负面影响，而F_KAL在过去几代人中对IBD等位基因显示出良好的结果。一些作者在圈养种群或实验条件下证明了这种现象；然而，在狗种群中没有描述过近亲繁殖净化的证据。尽管有各种繁殖方法，这些多基因疾病的等位基因似乎可以通过长期选择成功地从人群中清除。
