Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, P.R. China.
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1.
J Dairy Sci. 2017 Jun;100(6):4797-4806. doi: 10.3168/jds.2016-12334. Epub 2017 Apr 21.
Knowledge of the incidence of clinical mastitis (CM) and the distribution of pathogens involved is essential for development of prevention and control programs as well as treatment protocols. No country-wide study on the incidence of CM and the distribution of pathogens involved has been conducted in China. Core objectives of this study were, therefore, to determine the cumulative incidence of CM and the distribution of pathogens causing CM on large Chinese (>500 cows) dairy farms. In addition, associations between the distribution of CM pathogens and bedding materials and seasonal factors were also investigated. Bacterial culture was done on a total of 3,288 CM quarter milk samples from 161 dairy herds (located in 21 provinces) between March 2014 and September 2016. Additional data, including geographical region of herds, herd size, bedding types, and number of CM cases during the last month, were also recorded. Mean cumulative incidence of CM was 3.3 cases per 100 cows per month (range = 1.7 to 8.1). The most frequently isolated pathogens were Escherichia coli (14.4%), Klebsiella spp. (13.0%), coagulase-negative staphylococci (11.3%), Streptococcus dysgalactiae (10.5%), and Staphylococcus aureus (10.2%). Streptococcus agalactiae was isolated from 2.8% of CM samples, whereas Streptococcus uberis were isolated from 2.1% of samples, and 15.8% of 3,288 samples were culture-negative. Coagulase-negative staphylococci, E. coli, and other Enterobacter spp. were more frequently isolated in the northwest than the northeast or south of China. Streptococcus dysgalactiae, other streptococci, and Strep. agalactiae were more frequently isolated in winter (October-March), whereas E. coli and Klebsiella spp. were mostly isolated in summer (April-September). Streptococcus dysgalactiae was more often isolated from CM cases of herds using sand bedding, whereas Klebsiella spp. and other streptococci were more common in herds using organic bedding. The incidence of CM and distribution of pathogens differed among herds and better mastitis management is needed. Furthermore, geography, bedding materials, and season should be included when designing mastitis control and prevention schemes for Chinese dairies.
在中国，尚未开展过全国性的奶牛临床型乳房炎发病率和病原菌分布调查研究。因此，本研究的主要目的是确定中国大型（>500 头奶牛）奶牛场奶牛临床型乳房炎的累积发病率和引起乳房炎的病原菌分布，并调查病原菌分布与垫料和季节性因素之间的关系。2014 年 3 月至 2016 年 9 月期间，对来自 161 个牛场（分布在 21 个省份）的 3288 份奶牛临床型乳房炎乳区奶样进行了细菌培养。此外，还记录了牛场的地理位置、牛场规模、垫料种类以及上月乳房炎病例数等附加数据。平均每月每 100 头奶牛有 3.3 例临床型乳房炎（范围为 1.7 至 8.1）。最常分离到的病原菌是大肠杆菌（14.4%）、克雷伯氏菌属（13.0%）、凝固酶阴性葡萄球菌（11.3%）、停乳链球菌（10.5%）和金黄色葡萄球菌（10.2%）。从 2.8%的乳房炎奶样中分离到无乳链球菌，从 2.1%的奶样中分离到乳房链球菌，3288 个奶样中有 15.8%的为培养阴性。与中国的东北和南部相比，西北部更常分离到凝固酶阴性葡萄球菌、大肠杆菌和其他肠杆菌属。停乳链球菌、其他链球菌和无乳链球菌更常发生在冬季（10 月至 3 月），而大肠杆菌和克雷伯氏菌属多发生在夏季（4 月至 9 月）。沙质垫料牛场的临床型乳房炎病例中更常分离到停乳链球菌，而有机垫料牛场的临床型乳房炎病例中更常分离到克雷伯氏菌属和其他链球菌。不同牛场的乳房炎发病率和病原菌分布存在差异，需要更好的乳房炎管理。此外，在为中国奶牛场设计乳房炎防控方案时，应考虑地理位置、垫料种类和季节因素。
