Busato A, Trachsel P, Schällibaum M, Blum J W
Faculty of Veterinary Medicine, Institute of Animal Breeding, University of Berne, Bremgartenstrasse 109a, CH-3012, Berne, Switzerland.
Prev Vet Med. 2000 Apr 28;44(3-4):205-20. doi: 10.1016/s0167-5877(00)00104-5.
1+ were submitted for somatic cell counting (SCC), bacteriological examination and to test for antibiotic susceptibility. The SCC and germ-cell counts of monthly bulk-tank milk samples were available through Dairy Inspection and Advisory Services and milk production data of 567 herd-book cows were available from breeding associations. Possible individual and environmental predictors of subclinical mastitis were identified using logistic models adjusted for clustering of the data at herd and cow levels. Data were analyzed separately for cows from 7 to 100 and from 101 to 305 days post partum. Prevalences of subclinical mastitis at the quarter level were 21.2% for lactation period 7-100 days and 34.5% for 101-305 days post partum. The geometric mean SCC in bulk-tank milk samples was 85.6x10(3)cells/ml. Samples at 7-100 and 101-305 days post partum were positive for Staphylococcus aureus in 16.0 and 7.4%, for coagulase-negative Staphylococci in 51.5 and 50.6%, for Streptococcus agalactiae in 0.0 and 0.8%, for other Streptococci in 19.4 and 15.6%, for E. coli in 1.0 and 0.4%, and for Corynebacterium bovis in 25.7 and 45.1%, respectively. Risks of subclinical mastitis increased significantly with increasing days post partum and advancing age of cow. Cows that were sampled when staying in alpine dairies had considerably higher risks of subclinical mastitis than cows staying in home barns. Significantly lower risks of subclinical mastitis were observed in farms where CMT was performed regularly as a control measure. Bacteria in milk from cows with mastitis exhibited antibiotic resistance at a comparable frequency as found previously in conventional farms.
将1+的样本送去进行体细胞计数（SCC）、细菌学检查以及抗生素敏感性测试。通过乳品检验和咨询服务可获取每月大罐牛奶样本的体细胞计数和生殖细胞计数，并且可从育种协会获得567头系谱奶牛的产奶数据。使用针对牛群和奶牛水平数据聚类进行调整的逻辑模型来确定亚临床乳腺炎可能的个体和环境预测因素。对产后7至100天以及101至305天的奶牛数据分别进行分析。在泌乳期7至100天， quarter水平的亚临床乳腺炎患病率为21.2%，产后101至305天为34.5%。大罐牛奶样本中的几何平均体细胞计数为85.6×10³个细胞/毫升。产后7至100天和101至305天的样本中，金黄色葡萄球菌阳性率分别为16.0%和7.4%，凝固酶阴性葡萄球菌为51.5%和50.6%，无乳链球菌为0.0%和0.8%，其他链球菌为19.4%和15.6%，大肠杆菌为1.0%和0.4%，牛棒状杆菌为25.7%和45.1%。亚临床乳腺炎的风险随着产后天数增加和奶牛年龄增长而显著增加。待在高山奶牛场时采样的奶牛患亚临床乳腺炎的风险比待在家中牛舍的奶牛高得多。在将CMT作为控制措施定期进行的农场中，观察到亚临床乳腺炎的风险显著降低。患乳腺炎奶牛的牛奶中的细菌表现出的抗生素耐药性频率与之前在传统农场中发现的相当。 （注：原文中“quarter level”这里的“quarter”不太明确准确意思，可能是指某个特定划分的水平，比如乳房的某个象限等，暂按字面翻译）
