Effectiveness of mid-infrared spectroscopy for the prediction of detailed protein composition and contents of protein genetic variants of individual milk of Simmental cows.

Mid-infrared (MIR) spectroscopy was used to predict the detailed protein composition of 1,517 milk samples of Simmental cows. Contents of milk protein fractions and genetic variants were quantified by reversed-phase HPLC. The most accurate predictions were those obtained for total protein, casein (CN), \u3b1(S1)-CN, \u3b2-lactoglobulin (LG), glycosylated \u3ba-CN, and whey protein content, which exhibited coefficients of determination between predicted and measured values in cross-validation (1-VR) ranging from 0.61 to 0.78. Less favorable were results for \u3b2-CN (1-VR=0.53), \u3b1(S2)-CN, and \u3ba-CN (1-VR=0.49). Neither the content of \u3b1-LA nor that of \u3b3-CN was accurately predicted by MIR. Predicting the content of the most common milk protein genetic variants (\u3ba-CN A and B; \u3b2-CN A\ub9, A\ub2, and B; and \u3b2-LG A and B) was unfeasible (1-VR <0.15 for the content of \u3ba-CN genetic variants and 1-VR