A COMPARISON OF MASTITIS DETECTION METHODS IN DAIRY-CATTLE

The potential value of electrical conductivity, somatic cell count and California Mastitis Test (CMT) Score in composite milk samples as a screening test for subclinical mastitis was evaluated. The effect of genetic group was significant (P < 0.05) for conductivity and somatic cell count while the effects of parity and month of lactation were significant (P < 0.01) for all the 3 traits studied. Somatic cell count and CMT score increased from 1st to 4th parity while there was a general trend for increasing conductivity from 2nd to 4th parity. All 3 methods identified healthy cows accurately but failed to recognize a considerable proportion of infected cows. The error rate for misclassification was lowest for CMT score (9.1%), followed by somatic cell count (13.9%) and conductivity (29.4%). Composite strict foremilk samples from cows infected with primary pathogens had significantly (P < 0.01) higher conductivity than those from uninfected cows. Staphylococcus aureus were isolated in 60% of the milk samples and appeared to be in the major organism causing mastitis in this herd.