Diagnosis of subclinic mastitis in dairy cattle through somatic cell counts using two diagnostic methods

© 2018, Universidad del Zulia, Facultad de Ciencias Veterinarias. The objective was to compare somatic cell counts (CCS) using flow cytometry by imaging (CFI) and the traditional California Mastitis Test (CMT) in the diagnosis of subclinical mastitis in dairy cattle. A total of 44 milk samples were analyzed. Only the samples of mammary quarters that did not present clinical mastitis were considered for the study. The results obtained by CMT were classified as negative, with weak reaction, with distinguishable reaction and with strongly positive reaction. The CCS performed by flow cytometry was performed using the Sybr Green I stain. The Spearman correlation coefficient between the CCS and the CMT score was calculated, the Kendall's Tau-b coefficient was calculated between the response to CMT and three levels of CCS (less than 750 x 103; 750 x 103to 1500 x 103: more than 1500 x 103 cells per mL). Likewise, the level of agreement between the two tests was calculated using a threshold of 1000 x 103 cells per mL for the diagnosis of subclinical mastitis using the Cohen's Kappa index. The correlation coefficient when performing the Spearman analysis was 0.26 (P> 0.05), which is a low correlation level. Statistical analysis revealed that the results were not associated, since the association coefficient of Kendall's Tau-b was 0.15 (P> 0.05). The best efficiency of CMT was obtained in the CCS discrimination at a level of 1000 x 103 cells per mL with a sensitivity of 69.2% and a specificity of 71.0%; presenting a Cohen's Kappa index of 0.36 (P <0.05). The results of this work suggest that CFI can be a good alternative and a complementary tool to assess the health of the udder.