Tavornpanich Saraya, Johnson Wesley O, Anderson Randall J, Gardner Ian A
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Am J Vet Res. 2008 Jul;69(7):904-11. doi: 10.2460/ajvr.69.7.904.
To investigate herd characteristics and management practices associated with a high seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) in dairy herds in central California.
60 randomly selected cows from each of 21 dairy herds.
Sera of selected cows were tested for antibodies against MAP by use of an ELISA test kit. Cows with a test sample-to-positive control sample (S:P) ratio of > or = 0.25 were considered seropositive, and herds with > or = 4% seropositive cows were considered high-seroprevalence herds. Data on herd characteristics and management practices were collected via interviews with owners. Bayesian logistic regression was used to model the predictive probability of a herd having a high seroprevalence on the basis of various herd characteristics and management practices.
9 of 21 (43%) herds were classified as high-seroprevalence herds. Five variables (history of previous signs of paratuberculosis in the herd, herd size, exposing cattle to water from manure storage lagoons, feeding unsalable milk to calves, and exposing heifers < or = 6 months old to manure of adult cows) were included in the predictive model on the basis of statistical and biological considerations. In large herds, the predictive probability of a high seroprevalence of MAP infection decreased from 0.74 to 0.39 when management changed from poor to good practices. In small herds, a similar decrease from 0.64 to 0.29 was predicted.
The seroprevalence of MAP infection in California dairies may be reduced by improvements in herd management practices.
调查加利福尼亚中部奶牛场中与鸟分枝杆菌副结核亚种（MAP）高血清阳性率相关的畜群特征和管理措施。
从21个奶牛场中每个随机选取60头奶牛。
使用酶联免疫吸附试验（ELISA）试剂盒检测所选奶牛血清中抗MAP的抗体。检测样品与阳性对照样品（S:P）比值≥0.25的奶牛被视为血清阳性，血清阳性奶牛≥4%的畜群被视为高血清阳性率畜群。通过与畜主访谈收集畜群特征和管理措施的数据。采用贝叶斯逻辑回归，根据各种畜群特征和管理措施对畜群具有高血清阳性率的预测概率进行建模。
21个畜群中有9个（43%）被归类为高血清阳性率畜群。基于统计和生物学考量，预测模型纳入了5个变量（畜群既往副结核迹象史、畜群规模、让牛接触粪便储存池的水、用滞销牛奶喂犊牛、让6月龄及以下小母牛接触成年牛粪）。在大畜群中，当管理措施从差变为好时，MAP感染高血清阳性率的预测概率从0.74降至0.39。在小畜群中，预测有类似下降，从0.64降至0.29。
改善畜群管理措施可能降低加利福尼亚奶牛场MAP感染的血清阳性率。
