牛线性体型评定

对牛的线性体型评定的发展过程、特点及评定方法进行了简单的介绍，研究结果表明，体型评定数据的方差来源主要有年龄、鉴定员、胎次、畜群、产犊季节和公牛效应，公牛是体型性状极显著的来源；大多数报道认为体型性状的遗传力是中等的，体型性状间、体型性状与生产性状有较大的遗传相关；乳用性及乳用性状的线性评分值与产奶量呈强正相关；肢蹄与产奶量无关；与乳房形状和肢蹄有关的性状与畜群寿命相关最强；通过选择来提高乳房健康应提高前房附着和前乳头分布的育种值；公牛的近交系数与和体躯大小有关的性状呈负相关，母畜的近交系数只与乳头分布有显著的关系

Linear Type Classification for Cattle

The development process,characteristics and classifying methods of linear type classification are introduced.Results shows that the main resources of variance of classifying data are age,scorer,parity,herd,season of calfing and especially,sire effect;that heritabilities of type traits are moderate,larger genetic correlations exist among type traits and between type traits and production traits;the scores of dairy character and traits regard with milk have strong positive relationship with milk production;all researches shows feet and legs have no relationship with milk production;the traits associated with udder shape or feet have the largest correlation with herd life;the breeding values of fore udder touch and distribution of teats ought to be improved,if the udder health is to be improved by selection;the bull's coefficient of inbreeding and the traits related with body size significantly show negative relationship;the cow's coefficient of inbreeding have a relationship significantly only with teats distribution.