奶牛股部和乳房后部清洁度对日产奶量及体细胞数的影响

Effects of Thigh and Rear Udder Hygiene on Daily Milk Yield and Somatic Cell Score

为探究奶牛体表清洁度在实际生产中的应用意义,本研究通过评价河南省3个奶牛场472头泌乳天数在0~330d的中国荷斯坦奶牛股部清洁度和乳房后部清洁度,并结合2014年7月河南省牛奶记录系统（dairy herd improvement,DHI）中心提供的数据,对清洁度与平均日产奶量、体细胞数评分（somatic cell score,SCS）的关系进行分析,并探究两个清洁度评分之间的相关关系。采用广义线性模型（GLM）对数据进行统计分析,固定效应模型除清洁度评分外,还包括泌乳阶段效应和场—胎次效应等。结果表明,清洁度评分对SCS和平均日产奶量均无显著影响（P〉0.05）。股部清洁度评分对平均日产奶量回归系数为-0.14,即每增加1分,奶牛平均日产奶量降低0.14kg/头;乳房后部清洁度评分对平均日奶量回归系数为-0.02,每增加1分,奶牛平均日产奶量降低0.02kg/头。对于SCS,股部清洁度评分≥4分时,SCS≥5的比例极显著增加（P〈0.01）;乳房后部清洁度评分≥3分时,SCS≥5的比例有增加趋势（P=0.0546）。相关性检验和相关系数估计结果显示,股部和乳房后部清洁度评分间呈极显著正相关（P〈0.01）。因此,奶牛体表清洁度不仅是牛群的管理指标,而且可通过清洁度评分有效了解牛群乳房的健康状况,对日常生产过程具有很大帮助。

To investigate the importance of dairy cow hygiene for management,the objective of this research was to determine the relationship between hygiene scores and daily milk yield as well as somatic cell score（SCS）,and also the relationship between thigh and rear udder hygiene scores.The hygiene scores of thigh and rear udder were collected from 472 lactating cows in3 Holstein dairy farms in Henan province,and dairy herd improvement（DHI）data for July,2014 was also collected.After correcting the influence of fixed effects including lactating stage and dairy-parity,the effects of thigh and rear udder hygiene scores on daily milk yield and SCS were analyzed using SAS 9.1with general linear model（GLM）procedure.The results showed that thigh and rear udder hygiene scores had no significant effect on average daily milk yield and SCS（P〈0.05）.For average daily milk yield,the regression coefficients of thigh and rear udder hygiene scores were-0.14and-0.02,respectively.This meaned if thigh and rear udder hygiene scores increased 1score,average daily milk yield of each cow would decrease 0.14 and 0.02 kg,respectively.For SCS,when thigh hygiene score≥4,the proportion of cows with SCS≥5increased extremely significantly（P〈0.01）;when rear udder hygiene score ≥3,the proportion of cow with SCS≥5tended to increase（P=0.0546）.Significant test for correlation and correlation coefficient estimation results showed that,there was a extremely significantly positive correlation discovered between thigh and rear udder hygiene scores（P〈0.01）.Therefore,hygiene scores was not only a management indicator,also could help understand udder health condition,which was beneficial for management.