我国规模牛场奶牛个体生鲜乳体细胞数水平及影响因素探析

本研究旨在探析我国规模奶牛场奶牛个体生鲜乳体细胞数（SCC）的水平、分布和影响因素。利用SAS9.0的GLM模型,统计分析覆盖16个省（市、区）,33个规模奶牛场,23 351头中国荷斯坦牛,从2007年至2009年连续3年的225 775条奶牛个体生鲜乳SCC检测记录。结果表明：奶牛个体生鲜乳SCC的总体均值为48×104cell/mL,标准差为117×104cell/mL,个体生鲜乳SCC波动范围较大;其中,77.9%的奶牛个体,其生鲜乳SCC小于50×104cell/mL,对群体混合样生鲜乳SCC的影响系数为0.26;11.3%的奶牛个体,其生鲜乳SCC介于50×104～100×104cell/mL之间,乳房处于隐性感染状态,对群体混合样生鲜乳SCC的影响系数为0.16;10.8%的奶牛个体,生鲜乳SCC大于100×104cell/mL,理论上乳房处于临床感染状态,对群体混合样生鲜乳SCC的影响系数为0.58。奶牛个体生鲜乳体细胞数评分（SCS）呈正态分布,与奶牛个体因素（产奶量、乳脂率、乳蛋白含量、胎次和泌乳阶段）和环境因素（泌乳月份、泌乳季节）差异极显著（P〈0.01）,与奶牛养殖区域、奶牛场差异不显著（P〉0.05）。我国规模奶牛场奶牛个体生鲜乳SCC主要在50×104cell/mL以下,依据影响参数能实现对生鲜乳SCC水平的调控。

Analysis of Somatic Cell Counts in Raw Milk of Individual Dairy Cow from Dairy Farm in China

The objectives of this study were to analyze total average value,distribution frequency and mainly impact factors ofsomatic cell counts（SCC）in raw milk from individual dairy cow.The total data were from 33 dairy farms in China,23 351 Chinese Holstein cows,covering with 16 provinces,225 775 raw milk SCC from 2007 to 2009,and analysed by GLM model of SAS9.0.The results showed that： the total average of SCC in raw milk from individual dairy cow was 48（104cell/mL） with the standard deviation of 117（104cell/mL）;Under the different cell count grades,the distribution frequency and influence coefficient of SCC,which were defined as the influence of individual dairy cow on total group of dairy cows,respectively were about 77.9% and 0.26,at SCC≤50（104cell/mL）grade no mastitis;at subclinical mastitis 50SCC≤100（104cell/mL） grade,about 11.3% and 0.16;and at clinical mastitis SCC100（104cell/ml）grade,about 10.8% and 0.58.It was a normal distribution of the Somatic Cells Score（SCS）.There was significant difference（P0.01）of SCS between the factors that were from individual dairy cow（dairy parity,milk yields,milk fat,milk protein,stage of lactation） and from environmental（lactation month,lactation season）,and no significant differences（P0.05） of SCS between farming region and different dairy farm.In a word,the total average value and distribution frequency of SCC in individual raw milk from dairy farms were not exceed 50×104 cell/mL;with these data,we could control and keep the balance with the SCC in raw milk in practice.