Abstract：
Subclinical mastitis (SCM) is a major health problem of dairy animals in India and across the globe. An identification of potential risk factors of SCM can help for efficient udder health management in dairy animals. In this study, apparently healthy cows (HF crossbred: n = 45; Deoni: n = 43) were screened for SCM during different seasons through milk somatic cell count (SCC: reference test using 200 × 103 cells/ml as cut off value), California mastitis test (CMT) and differential electrical conductivity (DEC) test at an organized research farm. SCM positive milk samples (n = 34) were inoculated in selective media for Coliform sp., Streptococcus sp. and Staphylococcus sp. and DNA was isolated (n = 10) for species confirmation by 16s rRNA method. Both bivariate and multivariate models were used for risk assessment. We found the cumulative prevalence of 31 and 65% SCM in Deoni and crossbred cows, respectively. Screening of 328 crossbred cows under field conditions revealed point prevalence of 55% SCM. Multivariate analysis revealed stage of lactation (SOL), milk yield in previous lactation and test day milk yield in Deoni cows, as well as parity and mastitis treatment history in current lactation in HF crossbred cows as risk factors. SOL was a significant factor under field conditions. Receiver operated characteristic curve analysis revealed better accuracy of CMT than DEC. We found more mixed infections due to Staphylococcus sp. and Streptococcus sp. in culture, while 16s rRNA based molecular method revealed lesser-known pathogens associated with SCM. It is concluded that SCM prevalence rate is higher in crossbred than indigenous cows and these breeds have different risk factors for SCM. HF crossbred cows had similar SCM prevalence rate under different farming conditions, where CMT can be used for SCM diagnosis with excellent accuracy. The 16s rRNA method is useful for specific identification of lesser known and emerging mastitis pathogens.
摘要：
亚临床乳腺炎（SCM）是印度和全球产奶动物的主要健康问题。识别SCM的潜在危险因素可以帮助对奶牛进行有效的乳房健康管理。在这项研究中,通过乳体细胞计数（SCC：使用200×103个细胞/ml作为截止值的参考测试），在不同季节筛选了明显健康的奶牛（HF杂交：n=45；Deoni：n=43），加州乳腺炎测试（CMT）和微分电导率（DEC）测试在一个有组织的研究农场。将SCM阳性牛奶样品（n=34）接种在大肠杆菌的选择性培养基中。,链球菌。和葡萄球菌。并通过16srRNA方法分离DNA(n=10)用于物种确认。双变量和多变量模型均用于风险评估。我们发现Deoni和杂交母牛中31％和65％的SCM累积患病率，分别。在田间条件下对328头杂交母牛进行筛选，发现点患病率为55％。多变量分析显示哺乳期（SOL），Deoni奶牛先前泌乳的产奶量和测试日的产奶量，以及HF杂交母牛当前泌乳中的胎次和乳腺炎治疗史作为危险因素。在现场条件下，SOL是一个重要因素。接收器工作特性曲线分析显示，CMT的精度优于DEC。我们发现更多的混合感染是由葡萄球菌引起的。和链球菌。在文化中,而基于16srRNA的分子方法揭示了与SCM相关的鲜为人知的病原体。结论是，杂交母牛的SCM患病率高于本地母牛，并且这些品种具有不同的SCM危险因素。HF杂交母牛在不同养殖条件下的SCM患病率相似，其中CMT可用于SCM诊断，具有出色的准确性。16srRNA方法可用于特异性鉴定鲜为人知的和新兴的乳腺炎病原体。
