Estimating the nutritional quality of milk fat in cow milk Estimation of Fatty Acid Profile in Cow Milk by Mid-Infrared Spectrometry H. Soyeurt1,2, P. Dardenne3, G. Lognay1, P. Mayeres1,4, C. Bertozzi4 and N. Gengler1,5 1 Gembloux Agricultural University, Passage des Déportés 2, B-5030 Gembloux, Belgium, E-mail: soyeurt.h@fsagx.ac.be 2 F.R.I.A., B-1000 Brussels, Belgium 3 Walloon Agricultural Research Centre, Quality Department, B-5030 Gembloux, Belgium 4 Walloon Breeders Association, B-5530 Ciney, Belgium 5National Fund for Scientific Research, B-1000 Brussels, Belgium The message Estimating the nutritional quality of milk fat in cow milk The reference analysis : Gas Chromatography is expensive and time consuming  Mid-Infrared Spectrometry becomes a good alternative Objective Estimating the fatty acid contents by Mid-Infrared Spectrometry Methods Between April and June 2005, 600 milk samples were analysed from 275 cows derived to 6 breeds Percentage of milk fat for these ones ranged between 2.97 and 7.73 PCA analysis to choose the calibration samples Reference data : gas chromatographic analysis Spectral data for these samples calibration equations by using the PLS regression Results Ratio of SECV to SD was influenced by a polynomial relationship with the concentrations of fatty acid in milk (r² = 0.78) (result not shown). Predicted equations to be useful : a high R²CV, a little SECV and a good repeatability of chromatographic data. SD = standard deviation; SEC = standard error of calibration; R²c = calibration coefficient of determination; R²cv = cross-validation coefficient of determination SECV = standard error of cross-validation Conclusions Calibration equations which predict C12:0, C14:0, C16:0, C16:1 9-cis, C18:1, saturated and monounsaturated fatty acids in milk could be used. New perspectives in milk quality control and by extension of its current use by milk recording it has the potential to help improve the quality of milk produced on farms. Acknowledgements: The first author who is F.R.I.A Fellow acknowledges this support, FNRS, the Walloon Regional Ministry of Agriculture, the Milk Committee of Battice (Belgium).