Powell R L, Norman H D, Cowan C M
Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350, USA.
J Dairy Sci. 1996 May;79(5):895-9. doi: 10.3168/jds.S0022-0302(96)76438-X.
Examination of the existence of pleiotropy or linkage of bovine leukocyte adhesion deficiency with other traits and of the impact of removal of the recessive, undesirable allele on genetic progress for those traits has been limited. Frequency of carriers among 6400 Holstein bulls tested was 8.2%; however, reporting was incomplete, and, therefore, the estimate of carrier frequency was biased downward. For AI-sampled bulls, carrier frequency reached a high of 23% for bulls sampled during 1989 but declined to 0% since then because of DNA testing and culling. Association of the allele with yield, productive life, and somatic cell score was examined with a model in which the daughter yield deviation minus the mean of parent evaluations was explained by carrier status. A significant negative relationship was found with protein yield when effect of sires was ignored; all associations were unfavorable. Linkage was examined by applying the model for each of four sire families; only protein yield for one sire was significantly and negatively related to the recessive allele. Carrier bulls currently are labeled, and some continue to be used actively in AI because of superiority for other traits. Consequential pleiotropy of the allele or linkage of the locus with the traits studied is unlikely. Genetic progress for these performance traits will not be impeded by failure to sample carrier bulls.
对牛白细胞黏附缺陷的多效性或与其他性状的连锁关系，以及去除隐性不良等位基因对这些性状遗传进展的影响的研究一直有限。在检测的6400头荷斯坦公牛中，携带者的频率为8.2%；然而，报告并不完整，因此携带者频率的估计值偏低。对于人工授精抽样的公牛，1989年抽样的公牛携带者频率高达23%，但自那时起由于DNA检测和淘汰，该频率降至0%。采用一种模型来检验该等位基因与产量、生产寿命和体细胞评分之间的关联，在该模型中，女儿产量偏差减去亲本评估均值由携带者状态来解释。当忽略父系效应时，发现与蛋白质产量存在显著的负相关关系；所有关联都是不利的。通过对四个父系家系中的每一个应用该模型来检验连锁关系；只有一个父系的蛋白质产量与隐性等位基因存在显著的负相关。目前，携带者公牛已被标记，并且由于在其他性状上的优势，一些公牛仍在积极用于人工授精。该等位基因不太可能存在伴随多效性或该基因座与所研究性状的连锁关系。未能对携带者公牛进行抽样不会阻碍这些生产性能性状的遗传进展。
