Maxa J, Sharifi A R, Pedersen J, Gauly M, Simianer H, Norberg E
Institute of Animal Breeding and Genetics, University of Göttingen, 37075 Göttingen, Germany.
J Anim Sci. 2009 Jun;87(6):1888-95. doi: 10.2527/jas.2008-1319. Epub 2009 Feb 27.
In this study, influential factors and (co)variance components for survival to 24 h after birth were determined and estimated for Texel, Shropshire, and Oxford Down, the most common sheep breeds in Denmark. Data from 1992 to 2006 containing 138,813 survival records were extracted from the sheep recording database at the Danish Agricultural Advisory Service. Estimation of (co)variance components was carried out using univariate animal models, applying logistic link functions. The logistic functions were also used for estimation of fixed effects. Both direct and maternal additive genetic effects, as well as common litter effects, were included in the models. The mean survival to 24 h after birth was 92.5, 91.7, and 88.5% for Texel, Shropshire, and Oxford Down, respectively. There was a curvilinear relationship between survival to 24 h after birth and birth weight, with survival less for light and heavy lambs. Male lambs, as well as lambs from ewes in the first parity or with difficult lambing, had the least survival to 24 h after birth. Survival to 24 h after birth was greater in twin-born Texel and Shropshire lambs compared with singletons and vice versa in Oxford Down. Estimates of direct heritability were in the range from 0.05 to 0.07. Maternal heritability estimates were slightly greater (0.06 and 0.07) than direct heritabilities in Texel and Shropshire and less (0.04) in Oxford Down. The estimated genetic correlations between direct and maternal effects for survival to 24 h after birth were negative, which will make breeding for this trait more difficult. However, on the basis of estimated genetic parameters, it can be concluded that it is possible to improve survival to 24 h after birth in meat sheep breeds by accounting for both direct and maternal genetic effects in breeding programs.
在本研究中，对丹麦最常见的绵羊品种特克塞尔羊、萨福克羊和牛津唐斯羊出生后存活至24小时的影响因素和（协）方差组分进行了测定和估计。从丹麦农业咨询服务处的绵羊记录数据库中提取了1992年至2006年的数据，其中包含138,813条存活记录。使用单变量动物模型并应用逻辑链接函数进行（协）方差组分的估计。逻辑函数也用于固定效应的估计。模型中纳入了直接和母体加性遗传效应以及共同的窝效应。特克塞尔羊、萨福克羊和牛津唐斯羊出生后存活至24小时的平均存活率分别为92.5%、91.7%和88.5%。出生后存活至24小时与出生体重之间存在曲线关系，轻体重和重体重羔羊的存活率较低。雄性羔羊以及头胎母羊所生或难产母羊所生的羔羊出生后存活至24小时的概率最低。与单胎出生的羔羊相比，双胎出生的特克塞尔羊和萨福克羊出生后存活至24小时的概率更高，而牛津唐斯羊则相反。直接遗传力估计值在0.05至0.07之间。母体遗传力估计值比特克塞尔羊和萨福克羊的直接遗传力略高（分别为0.06和0.07），而牛津唐斯羊的则较低（0.04）。出生后存活至24小时的直接和母体效应之间的估计遗传相关性为负，这将使该性状的育种更加困难。然而，根据估计的遗传参数，可以得出结论，在肉羊品种的育种计划中考虑直接和母体遗传效应，有可能提高出生后存活至24小时的概率。
