Principal components analysis on body size indices of adult fat-tail sheep including body height, body length, body weigh,chest circumference, tail length and tail width was conducted by SPSS to get the dendrogram of body size and representative principal components which can provide a reference for fat-tail sheep's breeding and selection. The result showed that between-group linkage, Ward's method, Furthest neighbor could led to similar results. The principal components analysis divided the body size into three relatively independent principal components whose cumulative contribution rate was 87.042%, as the contribution rate of first principal component was 59.043%, while its high-load index were body height and body length named as height factor. The second principal component's contribution rate was 16.919%; its high-load index were body weight and chest circumference named as body factor. The high-load index of the third principal with a contribution rate of 11.081% were tail length and tail width called tail shape factor. The contribution of the first principal component accounted for more than half of the cumulative contribution, thus is the major source of variation of adult fat-tail sheep's body size which should be considered as the main factor in selection to improve the breeding efficiency.%选取了成年大尾寒羊的体长、体高、体重、胸围、尾长、尾宽,利用SPSS软件对以上体尺指标进行主成分分析.结果表明,主成分分析将体尺指标区分为3个相对独立的主成分,3个主成分的累积贡献率为87.042%.第一主成分的贡献率为59.043%,其中的高载荷指标有体高和体长,将其命名为高度因子；第二主成分的贡献率为16.919%,其中的高载荷指标有体重和胸围,命名为躯体因子；第三主成分的贡献率为11.081%,其中的高载荷指标有尾长和尾宽,命名为尾形因子.第一主成分贡献率占累积贡献率的一半以上,说明它是大尾寒羊成年个体体尺变异的主要来源,因此,在大尾寒羊的选育工作中应以第一主成分为主体进行选择,来提高大尾寒羊的选育效率.
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