Effectiveness of mid-infrared spectroscopy for prediction of the contents of calcium and phosphorus, and titratable acidity of milk and their relationship with milk quality and coagulation properties

Individual milk samples from Holstein Friesian cows were collected and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES) and titration for the determination of calcium (Ca), phosphorus (P) and titratable acidity (TA) contents, respectively. Prediction models were obtained using partial least squares (PLS) regression analyses using two statistical packages. The average Ca, P and TA were 1156 mg kg(-1), 934 mg kg(-1) and 3.42 degrees SH 50 mL(-1), respectively. Pearson's correlations between Ca and P and other milk traits were significant (P < 0.05) and ranged from 0.16 to 0.53 for chemical composition traits and from 0.17 to -0.35 for milk coagulation properties (MCP). Results from the two statistical packages were comparable. Prediction models using MIR spectroscopy were satisfactory for Ca, P and TA, with coefficients of correlation of cross-validation greater than 0.73. Moreover, the study highlighted favourable relationships of these traits with milk coagulation properties.