Variability Factors of Milk Fat-Protein Concentration Ratio

Abstract

The milk fat-protein concentration ratio (FPR) may be an important index of cow health and rumen fermentation in diary herds. This is supported by research that indicates FPR may be useful in the diagnosis of negative energy balance and in predicting abomasal displacement. Additionally, FPR will vary by rumen fermentation-acid profile because diets rich in starches and sugars commonly depress milk fat concentration and increase milk protein concentration. This is possibly mediated by rumen hydrogenation of fats to the trans-configuration and the insulin response to propionic acid production. Interpretation of FPR is currently difficult because variability factors are not completely known. The objectives of this report are to describe nonnutritional factors affecting the variability of FPR and improve diagnostic interpretation of FPR in dairy herds.