用奶牛乳房性状预测产奶量的研究

Prediction of the milk yield with the udder traits in dairy cattle

选择西安市草滩农场第四奶牛场第二泌乳期的奶牛 30头 ,测定乳房宽、乳房深、乳房长、乳房围、乳静脉直径、体长、体高、胸围、胸深、十字部高、腰角宽、尻长和 30 5 d产奶量 ,经相关系数分析 ,剔除了与 30 5 d产奶量相关不显著的体尺指标 ,以前 5项乳房性状为自变量 ,以 30 5 d产奶量为因变量 ,采用通径系数分析方法 ,计算了各自变量对依变量的通径系数 ,用多元回归分析方法 ,经统计检验后保留作用大的自变量 ,最后建立了 R=0 .930 6的“最优”回归方程。经对 30头奶牛 30 5 d产奶量进行估测 ,所得估测值与实际值的均数经差异显著性检验(t检验 ) ,差异不显著 (P>0 .0 5 )。

Data for this study were collected from 30 dairy cattle in the second milk period in Fourth Dairy Cattle Farm of Caotan Farm of Xian City.The udder width,the udder depth,the udder length,the udder girth,mammary vein diameter,the body length,withers height,chest girth,chest depth,hip height,pin bone width,rump length and 305 days yield were measured.The correlation coefficients were calculated.After omission of the latter seven body characters with insignificant effects of every correlation coefficient between each of them and 305 days yield identified statistically,the first five udder characters were used as independent variables,and 305 days yield was used as a dependent variable for path analysis?Using the method of multi way regression analysis,an optimum five way linear regression equation was established with R =0.930 6.By estimating the 305 days milk yield of 30 dairy cattle,the average value of estimated figure and real figure,measured by difference significance test,was not significant ( P >0.05).