Prevalence and Risk Factors of Subclinical Mastitis in Lactating Cows in Northwest China.

The aim of this study was to investigate the prevalence and risk factors of subclinical mastitis (SCM) in lactating cows in northwest China. A total of 1,590 lactating cows from 38 different-scale dairy farms located in Gansu province and Ningxia Hui autonomous region were selected for this study. SCM was confirmed by California Mastitis Test. Cow-level risk factors including age, parity, lactation stage, milk yield, clinical mastitis history, teat damage, hygienic-sanitary quality, milking method and season were identified through univariate analysis and multivariate analysis using SPSS 19.0. In the two regions, the prevalence of SCM was 25.92% at cow level and 16.40% at quarter level. On large-, medium- and small-scale dairy farms, the SCM incidence was 21.46%, 26.74% and 33.16%, respectively. Among the potential risk factors, parity, lactation stage, clinical mastitis history and teat damage significantly influenced the occurrence of SCM (P<0.01) at cow level. This study indicated high-level prevalence of SCM and identified four risk factors for SCM which can be addressed by practical management of dairy cows for the local farms. [ABSTRACT FROM AUTHOR]