title: An evaluation of protein/fat ratio in first DHI test milk for prediction of subsequent displaced abomasum in dairy cows.
abstract: First DHI test milk that was sampled prior to displaced abomasum (DA) diagnosis was used to evaluate milk protein/fat ratio (PFR) for prediction of subsequent DA in dairy cows. Odds ratio, sensitivity, specificity, and likelihood ratio were determined. Twenty-seven DA cases were matched to 3 controls per case by herd and calving date. Milk was tested at a median of 19 d after calving, which was 8 d prior to the median time of DA diagnosis. Adjusted for parity and days in milk, a protein/fat ratio < or = 0.72 was 8.2 times more likely to come 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 DA was 80% and the specificity was 68%. A receiver operating characteristics 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 ratio indicated that protein/fat ratios < or = 0.62 are 3.8 times more likely to come from cows that are diagnosed subsequently with DA than from cows without DA. The protein/fat ratio in 1st DHI test milk may predict subsequent DA in dairy cows.
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph.
authors.forename: T D
authors.initials: TD
authors.lastname: Geishauser
authors.forename: K E
authors.initials: KE
authors.lastname: Leslie
authors.forename: T F
authors.initials: TF
authors.lastname: Duffield
authors.forename: V L
authors.initials: VL
authors.lastname: Edge
mesh_terms: D000018:Abomasum / Q000002:abnormalities*; D000818:Animals; D002417:Cattle / Q000002:abnormalities*; D002418:Cattle Diseases / Q000453:epidemiology*; D005189:False Positive Reactions; D005260:Female; D008055:Lipids / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis*; D009864:Ontario; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013272:Stomach Diseases / Q000453:epidemiology / Q000662:veterinary*
chemical_list: D008055:Lipids; D008894:Milk Proteins