Department of Farm Animal Health, Utrecht University, PO Box 80.151, 3508 TD Utrecht, the Netherlands.
J Dairy Sci. 2011 Feb;94(2):992-7. doi: 10.3168/jds.2010-3472.
Worldwide, classical control strategies based on hygiene and culling of infected animals have been implemented to eradicate Johne's disease. Breeding for disease resistance may be a useful additional tool to control the disease. The aim of this study was to estimate genetic parameters for the presence of a Mycobacterium avium ssp. paratuberculosis specific antibody response in milk of Dutch Holstein-Friesian cows using subsets of data based on within-herd test prevalence. The analyzed data set consisted of milk samples of 684,364 animals from 12,077 herds collected during the routine milk production scheme. Milk samples were tested for antibodies specific for Johne's disease by an ELISA test. Heritability estimates were calculated for 4 different subsets of data to determine the sensitivity of heritability for within-herd test prevalence. Results expressed as percentage of the sample to positive ratio were analyzed with a sire-maternal grandsire model with fixed effects for parity, year of birth, lactation stage, and herd; a covariate for milk yield at test day; and random effects for sire, maternal grandsire, and error. The estimated heritability ranged from 0.031 for the complete data set to 0.097 for herds with a test prevalence of at least 10%. Cross-validation was applied to determine which of the subsets of data produced the most accurate estimated breeding values. Results showed that for genetic selection to contribute to disease control, breeding values were estimated most accurately from herds with at least 2 animals that tested positive. In this subset the heritability was 0.041.
在全球范围内，基于卫生和淘汰感染动物的经典控制策略已被用于根除约翰氏病。针对疾病的抗性育种可能是控制该病的另一种有用工具。本研究的目的是使用基于群内检测流行率的子数据集，估计在荷兰荷斯坦弗里森奶牛牛奶中存在分枝杆菌副结核特异性抗体反应的遗传参数。分析的数据集中包含了 12077 个牧场的 684364 头奶牛的牛奶样本，这些样本是在常规牛奶生产计划中收集的。牛奶样本通过 ELISA 测试检测针对约翰氏病的抗体。针对 4 种不同的数据集子集计算了遗传力估计值，以确定遗传力对群内检测流行率的敏感性。用具有固定产犊胎次、出生年份、泌乳阶段和牧场效应的父本-母本曾祖父模型，以及一个与测试日牛奶产量有关的协变量，以及父本、母本曾祖父和误差的随机效应，分析了以样本阳性比值表示的结果。估计的遗传力范围从完整数据集的 0.031 到检测流行率至少为 10%的牧场的 0.097。应用交叉验证来确定哪些数据集子集产生了最准确的估计育种值。结果表明，为了使遗传选择对疾病控制做出贡献，最准确的估计育种值来自至少有 2 头检测呈阳性的动物的牧场。在这个子集中，遗传力为 0.041。
