To investigate the growth and development regulations of crossbred Holstein cows for early selection of the core herd of dairy-purposed crossbred Holstein population and fixation of good characters, crossbred Holstein cows were randomly selected for body size and body size indices analysis. With the increasing of crossbreeding generations, body length index and pin bone width index of 0.5-year-old crossbred Holstein cows also increase, while body index, heart girth index gradually decrease. Dairy-purpose or dairy-beef dual purpose conformation basically form. These proved the validity of the theory, body sizes and pin bone index are bigger than population means, body length index, body index and heart index are smaller than population means.%[目的]本文旨在寻找陇县改良母牛的生长发育规律,为乳用改良牛核心群的早期选育,固定乳用改良后代的优良性状况提供依据.[方法]随机抽取陇县改良母牛(0.5岁、3岁、5岁以上)个体体尺、体尺指数,采用方差分析和多重比较进行综合分析,通过各年龄组合内不同改良后代之间,横向比较不同年龄组合(0.5岁～3岁～5岁以上),纵向比较其体尺、体尺指数,[结果]显示改良个体0.5岁的体长指数,尻宽指数随着改良代数增加逐渐增大,体躯指数,胸围指数随着改良代数增加逐渐缩小,乳用体型及乳肉体型已基本具备等5条具有规律性.[结论]对0.5岁的早期个体,依照平均体尺、平均体尺指数,坚持"体尺绝对指标高于平均数,体长指数,体躯指数,胸围指数低于平均数,尻宽指数高于平均数"的早期乳用核心群的选育结论,对乳用改良工作具有一定的指导意义.
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