Mid-infrared spectroscopy is used to quantify the milk fat and milk protein in dairy cattle performance control. It allows for predicting the fatty acid profile of milk fat and other substances in milk samples, such as acetone, beta-hydroxybutyrate (BHB), citrates, and lactoferrin. Those can be used as health indicators. Using spectral data of milk to predict new, relevant phenotypes in livestock allows the extension of breeding to expensive and difficult-to-obtain traits such as individual methane production or feed efficiency in dairy cows.