乳房炎疫苗对奶牛体细胞数及隐性乳房炎的影响研究

Study on the Effects of Mastitis Vaccine on the Somatic Cell Count and Subclinical Mastitis

乳房炎是奶牛最主要的疾病之一,每年都会给奶牛业带来巨额的经济损失。针对不同的病原菌,所采取的防控措施也有所不同。本研究引入经欧盟EMA认证的乳房炎大肠杆菌和葡萄球菌二联灭活疫苗,在国内两个奶牛场进行临床测试,验证其临床使用效果。选择地处西安和白银的两个规模化奶牛场,根据奶牛进入干奶期前的奶样检测结果、产量、体况评分等指标,筛选出240头奶牛入选临床测试,按照免疫程序进行免疫后,在产犊后的第2周、第6周、第10周、第14周和第18周分别采奶样检测体细胞数,并对奶样中的细菌进行分离鉴定,确定该疫苗对隐性乳房炎发病状况以及奶牛体细胞数的影响。结果显示,疫苗表现出了优异的效果,特别是第14周,免疫组奶牛的保护率远高于对照组,差异显著(P<0.05),其他阶段免疫组的保护率也均高于对照组。两个奶牛场在干奶前1周免疫组的体细胞数和对照组几乎相近,而进入泌乳期后免疫组的体细胞数持续低于对照组,说明试验牛在免疫疫苗后,抗体对病原菌产生了积极作用,缓解了炎症反应,降低了乳中体细胞数。这也从另一方面说明该疫苗具有提高奶牛机体对抗特异性病原的作用。

Mastitis is one of the main diseases for dairy cattle, which always causes huge economic losses to dairy industry every year. The mastitis vaccine which authorized by European medicines agency（EMA） has been introduced into our clinical research in two dairy farms which are located in Xi ＇an and Baiyin, to verify its clinical effect in Chinese dairy farm. According to the milk samples testing results, production, and body condition score before dry cows period, totally 240 dairy cows was choosing for clinical tests, vaccinated the cows according the immune program, follow the immune group and the control group at 2, 6, 10, 14 and 18 weeks after calving, respectively sampling the milk and testing milk somatic cell count, separating pathogen bacteria in milk samples, to make sure the vaccine effect on subclinical mastitis incidence and somatic cell count. The result showed good field effect, especially in 14 weeks, for the immune group, which is far higher than that of control group, P0.05, significant difference. For other phases, immune group was higher than the control group, too. For somatic cell count, the test results show that before a week of dry off, the somatic cell of immune group and the control group were almost same, but after calving, somatic cell count for immune group continuously less than controls, that means after vaccination, the body produced antibodies against pathogen invasion, the body＇s inflammatory response cause somatic cell count fell down. On the other hand, this also means the vaccine efficacy in improving cow immune system against specific pathogens.