乳房炎对中国荷斯坦牛测定日泌乳性能及体细胞数变化的影响

摘要

旨在研究乳房炎及病原菌组成对中国荷斯坦牛测定日泌乳性能及体细胞数变化的影响.本研究于2009年9月对江苏某奶牛场140头成年中国荷斯坦泌乳牛进行乳房炎检测和DHI测定,同时对隐性乳房炎阳性乳区进行病原菌分离鉴定,并分析了不同乳房炎类型和隐性乳房炎病原菌组成对测定日泌乳性能和乳中SCC变化的影响.结果表明,该牛场临床乳房炎、隐性乳房炎和正常奶牛比例分别为10.00％、51.10％和37.90％,其中隐性乳房炎以大肠杆菌和链球菌混合感染最多(19头,占26.00％),其次为链球菌单独感染(17头,占23.30％).由1种细菌单独感染的比例为26头(占36.11％),2种或2种以上细菌混合感染为44头(占61.11％).乳房炎类型对测定日产奶量、乳糖含量、体细胞数和体细胞评分4个指标影响达到极显著水平(P＜0.01),临床乳房炎和隐性乳房炎奶牛日产奶量和乳糖含量极显著低于正常奶,同时体细胞数和体细胞评分极显著高于正常奶,而临床乳房炎奶和隐性乳房炎奶在所有检测指标上均无显著差异,但临床乳房炎奶比隐性乳房炎奶体细胞数高出约100万·mL-1.不同病原菌组成类型对乳中体细胞数和体细胞评分有极显著影响(P＜0.01),而对其它性状无显著影响(P＞0.05).混合感染奶牛测定日产奶量极显著低于单独感染奶牛(P＜0.01),同时乳中体细胞数显著高于单独感染奶牛(P＜0.01).乳房炎类型对乳中SCC的变化趋势有显著影响(P＜0.01),正常奶牛维持较低SCC的能力较强,隐性乳房炎奶牛在下一泌乳月体细胞增加的可能性较大.不同隐性乳房炎病原菌组成类型对乳中SCC的变化无显著影响.奶牛生产中隐性乳房炎发病率高,危害性也最大,不同病原菌混合感染引起的隐性乳房炎对测定日产奶量和乳中体细胞数影响最大.该结果为奶牛场采取合理措施,降低隐性乳房炎发生率提供了参考.%The objective of this study was to investigate the effects of clinical mastitis and pathogen-specific mastitis on the test-day milk performance and the variation of SCC for Chinese Hol-stein. Clinical mastitis and sub-clinical mastitis were indentified using CMT method from 140 milking cows in a dairy farm, Jiangsu Province. In September, 2009, and the pathogens were indentified for the quarters of sub-clinical mastitis cow. The effects of clinical mastitis and pathogen-specific sub-clinical mastitis on the test-day milk performance and the variation of SCC were esti-mated by ANOVA. The proportion of clinical mastitis and sub-clinical mastitis cows were 10.00% and 51. 10%, respectively. In the sub-clinical mastitis cows, the most events was the mixed infected by Escherichia coli and Streptococcus spp (26. 00%) , following was Streptococcus spp (23. 30%). The proportion of cows infected by only one pathogen was 36. 11%,and the proportion of cows infected by more than two pathogens was 61. 11%. The effects of mastitis on test-day milk yield, lactose percentage, SCC and SCS were significant at P<0. 01 level. The test-day milk yield and lactose percentage for clinical mastitis and sub-clinical mastitis cows were less than that for healthy cows, and the SCC were higher than that in healthy cows. The pathogen types significantly affected SCC and SCS of cow. The test-day milk yield for sub-clinical mastitis cows infected by more than two pathogens were significant less than that in cows infected by only one pathogen, and the SCC were significant higher than that in cows infected by only one pathogen. The effect of mastitis on the variation of SCC was significant at P<0. 01 level. The healthy cows had higher ability to maintain low SCC in milk, and the possibility having more SCC for sub-clinical mastitis cows was increased . The pathogens types had no significant effect on the variation of SCC. The results indicate that the sub-clinical mastitis infected by more than two pathogens have more serious effects than sub-clinical mastitis infected by only one pathogen on the test-day milk yield and SCC in milk. These findings provide dairy producers with more information in which pathogen-specific sub-clinical mastitis cases should receive treatment and how to manage these cows.