【摘要】 选择西安市草滩农场第四奶牛场第二泌乳期的奶牛 30头 ,测定了乳房宽、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 (Y) ,计算了相关系数 ,剔除了与30 5 d产奶量相关系数不显著的 7个体尺指标 ,采用通径分析方法计算了以前 5个乳房性状为自变量对 30 5 d产奶量作依变量的通径系数、决定系数及相关指数。结果表明 ,乳房性状与 30 5 d产奶量的相关系数均达到极显著水平(P<0 .0 1) ,乳静脉直径和乳房围对 30 5 d产奶量的直接影响最大 ,是影响产奶量的主要因素 ;乳房宽对 30 5 d产奶量的直接影响最小 ,间接作用较大 ,主要通过乳房围间接影响 30 5 d产奶量 ;决定系数分析结果与通径分析结果有一致的变化趋势 ;所选乳房性状与 30 5 d产奶量的复相关指数 R2 =0 .86 6 0。更多还原

【Abstract】 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 ( X 1 ),the udder depth ( X 2 ),the udder length ( X 3 ),the udder girth ( X 4 ),mammary vein diameter ( X 5 ),the body length ( X 6 ),withers height ( X 7 ),chest girth ( X 8 ),chest depth ( X 9 ),hip height ( X 10 ),pin bone width ( X 11 ),rump length ( X 12 ) and 305 day yield ( Y ) were measured.The correlation coefficients were calculated.The latter seven body characters were omitted because of no significant correlation coefficient between each of them and 305 days yield.The first five udder characters were used as independent variables,and 305 day yield was used as a dependent variable for path analysis,path coefficients ( p ),determination coefficients ( d ) and correlation index ( R 2 ) were calculated.The results showed that 5 correlation coefficients between each udder character and the 305 day yield were significantly differente ( P <0.01),they are 0.541 1 ** ,0.611 8 ** ,0.629 5 ** ,0.718 2 ** ,0.620 2 ** .Mammary vein diameter ( X 5 ) and udder girth ( X 4 ) gave predominant direct effects ( P 5 =0.316 3 and P 4 =0.301 2) and determinacy on 305 day yield,they are the key effective factors.Udder width ( X 1 ) gave slightly direct effect ( P 1 =0.224 7) and significant indirect effect through udder girth on 305 day yield.It was clear from the result of high correlation index ( R 2 =0.866) that the path coefficient analysis could reveal the truthful relationship between the independent variables and the dependent variable.更多还原