EVALUATION OF A MILK TEST FOR DETECTION OF SUBCLINICAL KETOSIS

This study included 190 lactating cows from eight dairy farms and was designed to investigate the sensitivity and specificity of a milk test (Ketolac) for detecting subclinical ketosis in dairy cattle. Blood an d milk samples were collected between 38 and 50 days post partum, At a beta-hydroxybutyric acid concentration in blood of 1.2 mmol/L, the pr evalence of ketosis was 14%. A Response Operator Characteristic curve was drawn for two milk test values: 100 mu mol/L and 200 mu mol/L, Ass essment of several beta-hydroxybutyric acid cut-off values in blood sh owed that when 100 mu mol/L on the Ketolac milk test was defined posit ive, the most desirable sensitivity-specificity combination was achiev ed. This milk test can be routinely used to screen a herd for subclini cal ketosis.