线性模型对影响奶牛产奶性能的主要相关因素分析

利用一般线性模型研究各种因素对奶牛产奶性能的影响。牛场、胎次和产犊季节对奶牛产奶量影响差异极显著(P0.01),随着奶牛胎次的增加,奶牛产奶量增加;夏季产犊的奶牛产奶量最低,冬季产犊的最高;体细胞计数对奶牛产奶量没有显著性影响(P0.05),但随着体细胞数的增加,产奶量下降。牛场、胎次和体细胞计数对乳脂率有极显著的影响(P0.01),第三牛场平均乳脂率为4.38%,显著高于其他三个牛场;随着胎次的增加,乳脂率有下降趋势;随体细胞数增加,乳脂率升高;产犊季节对奶牛乳脂率没有显著影响(P0.05)。牛场、产犊季节和体细胞数对乳蛋白率的影响极显著(P0.01),体细胞数增加,乳蛋白率升高;夏季和秋季产犊的奶牛乳蛋白率较高,春季和冬季较低;胎次对乳蛋白率没有显著影响(P0.05)。表型相关分析表明:SCC与产奶量呈显著负相关(r=-0.158,P0.05),SCS与产奶量相关性接近显著水平(r=-0.140,P=0.055)。SCC/SCS与乳脂率、乳蛋白率呈正相关,但未达到显著性水平(P0.05)。

Study on Main Factors Affecting Milk Performance of Dairy Cows Using General Linear Model

General linear method was used to analysis factors affecting dairy milk performance.Results showed that dairy herd,lactation and calving season were significant effect on milk yield（P〈0.01）.The LSM（Least squares means）of milk yield increased with the rising of lactation.Cows that calved in winter produced the highest milk yields,and the lowest in summer.The different levels of SCC（Somatic cell count）were not significant effects on milk yield（P〉 0.05）,but milk yield declined with the SCC increase.The fat percentage LSM was extremely significant in different dairy herds,lactations and SCC levels（P〈0.01）,it was 4.38% in the third herd and higher than others.Fat percentage had a decreasing tendency with the lactations,and enhanced with SCC.Calving season had no significant effect（P〉0.05） on fat percentage.LSM of protein percentage was extremely significant in different dairy herds,lactations and SCC levels（P〈0.01）,and it increased with the increase in SCC.Protein percentage was high in cows calving in summer and autumn,and low in spring and winter.Lactations had no significant effect（P〉0.05） on protein percentage.Phenotypic correlation between SCC/SCS and milk yield,fat percentage,protein ratio were analyzed.Correlation between SCC and milk yield was significant（r=-0.158,P〈0.05）,Correlation of SCS and milk yield was-0.140,（P=0.055）.SCC/SCS had positive relationship with fat percentage and protein ratio,but not significant（P〉0.05）.