Evaluating cow welfare status from milk samples: effects of housing modifications on milk infrared spectra

Abstract The goal of this study was to isolate spectral fingerprints from milk Fourier transform infrared spectra that may reflect potential improvements in cow welfare, specifically comfort and ease of movement, resulting from modified housing configurations. Housing configuration modification treatments were tested across 3 animal trials, consisting of modified chain length (TCL), stall width (SW) and manger wall and stall length (MW/SL) configurations. The spectral analyses involved the use of principal components and mixed model analysis. Principal components were calculated from averages of mid-infrared spectra collected on the last weeks of treatment application in each of the animal trials. A significant effect of housing configuration was revealed. As an indication of animal comfort improvement, milk of cows assigned to longer chains revealed a trend of changes in multiple milk components (e.g., milk NPN, trans fatty acids, fat, and protein) that are consistent with changes in ruminal pH. These conclusions were inline with those drawn from the analysis of animal-based responses such as behavioral data and other outcomes. This study was able to reveal that housing modifications had a significant effect on milk spectra, with differences observed between the most and least restrictive treatments, translating into improved or reduced animal welfare status.