infrared Spectroscopy in Mixed Dairy Herds

Over the last years, healthy food has gained interest among consumers, especially with regard to the fat content of livestock products which has been associated to the risk of cardiovascular diseases. Individual milk samples (n = 12,624) of 2,977 Holstein-Friesian (HF), Brown Swiss (BS) and Simmental (SI) cows from 39 multibreed herds were analyzed for fat content, protein content, casein content and somatic cell count using mid-infrared spectroscopy (MIRS). Daily milk yield was also recorded. Groups of fatty acids (FA), expressed as percentage of milk fat, were predicted by MIRS: they were saturated (SFA), unsaturated (UFA), monounsaturated (MUFA) and polyunsaturated (PUFA) FA. Data were analyzed with a linear mixed model including the fi xed eff ects of month of sampling, parity, days in milk (DIM), herd, breed, and interactions between parity and breed, and DIM and breed. Th e random eff ects were cow nested within breed and residual. Milk of HF cows exhibited the lowest percentage of SFA (70.45%) and the highest of UFA (31.20%), and milk of SI cows was intermediate between that of HF and BS breeds for all groups of FA. Th e values of groups of FA across DIM were similar for the diff erent breeds. Results fro