AN EVALUATION OF PROTEIN FAT RATIO IN FIRST DHI TEST MILK FOR PREDICTION OF SUBSEQUENT DISPLACED ABOMASUM IN DAIRY-COWS/

First DHI test milk that was sampled prior to displaced abomasum (DA) diagnosis was used to evaluate milk protein/fat ratio (PFR) for predic tion of subsequent DA in dairy cows, Odds ratio, sensitivity, specific ity, and likelihood ratio were determined, Twenty-seven DA cases were matched to 3 controls per case by herd and calving elate, Milk was tes ted at a median of 19 d after calving, which was 8 d prior to the medi an time of DA diagnosis, adjusted for parity and days in milk, a prote in/fat ratio less than or equal to 0.72 was 8.2 times more likely to c ome from a cow subsequently diagnosed with DA than a protein/fat ratio > 0.72, Using the cut off value of 0.72, the sensitivity of PFR for D A was 80% and the specificity was 68%. A receiver operating characteri stics curve indicated that the minimum sum of false negative and false positive results was at a PFR cut off value of 0.72, The likelihood r atio indicated that protein/fat ratios less than or equal to 0.62 are 3.8 times more likely to come from cows that are diagnosed subsequentl y with DA than from cows without DA, The protein/fat ratio in Ist DHI test milk may predict subsequent DA in dairy cows.