A comparison of indirect methods for diagnosis of subclinical mastitis in lactating dairy cows

A total of 1014 samples taken from Lithuanian cows at the end of milking were tested on several parameters: milk reaction with Mastest (developed, tested, and produced at the Lithuanian Veterinary Institute), California Mastitis Test (CMT), Bernburg, Profilac reagent, Eimü-milchtest. Somatic cell count (SCC) was established using the flow cytometry method and Anadis F device; electrical conductivity (EC) was measured using a Mastiidiindikaator device made in Estonia. Electrical conductivity of the samples taken from healthy cows was 4.5-6.0 mS/cm, while EC in the samples taken from cows with subclinical mastitis was 6.1-8.5 mS/cm. Even though electrical conductivity of milk produced by the cows with mastitis tends to increase, it does not always correlate with SCC. Mastest results correlate best (95.5-100%) somatic cell count in milk when reaction of milk with milk is rated to be 1, 2, and 5 points, while the poorest correlation (87.62%) is at a rating of 3 points. Mast test results correlate well with those of other tests. Total coefficient of correlation between Mastest and Bernburg reagent r = +0.985, between Mastest and Profilac r = +0.980, between Mastest and Eimü-milchtest r = +0.966. The best correlation (99.39-100%) between Mastest and CMT is at a rating of 1 and 5 points. At the intermediary ratings (2-4 points) test results correlate 95.96-99.05%. Overall correlation coefficient r = +0.997.