Retrospective analysis on somatic cells count trend in Staphylococcus aureus cows' mastitis

Abstract

cells count (SCC) of two successive samplings. The analysis was performed to identify the associations between SCC trend with retrospective and transversal milk quality indicators, and mastitis. From a BIOAMR database, 28 cows with a posteriori diagnosed mastitis with Staphylococcus aureus (4/28 cases were methicillin-resistant Staphylococcus aureus – MRSA) were sampled. The trend of SCC was Spearman's rho correlated with previous lactose (rs = +0.785, p=0.03), pH (rs = +0.662 at p=0.019), and current SCC measurements (rs = +0.781, at p=0.000). Increasing trend of SCC was retrospectively associated with lactose content (Z = -2.152 at p = 0.031), pH (Z = -2.152 at p = 0.031) SCC at first measurement (Z = - 1.764 at p = 0.078) and currently associated with SCC (Z = -3.316 at p = 0.001), fat content (Z = -1.88 at p = 0.060) and fat/protein ratio (Z = -1.717 at p = 0.086). The 28 samples of the study did not revealed strong association between SCC trend and type of Staphylococcus aureus (p = 0.186 by Mann-Whitney test), even if MRSA had a higher increasing trend of SCC in comparison whit S. aureus (non-MRSA) infections (1403.5 vs. 288.2 thousands somatic cells). By preliminary results the trend of somatic cells could be an indicator in detection of mastitis but more case studies are necessary.