Factors affecting herbage and milk fatty acid composition from permanent grasslands in the Italian Alps

This research aimed to highlight which factors, related to climatic conditions and herbage characteristics, can affect the fatty acid (FA) composition of permanent grasslands and remain determinant in influencing the FA composition of derived milk. The FA profiles of 159 herbage samples from permanent grasslands and their chemical and botanical compositions, and the characteristics of growing site were collected in the Italian western Alps. The milk from grazing herds and the related diet composition were collected. A principal component analysis was performed on herbage FA composition and growing conditions. A correlation matrix was performed on milk FA concentrations, herbage characteristics and diet composition. Concerning herbage FA composition, C16:0, C18:0 and C18:1c9 concentrations were positively related to herbage DM content, legumes proportions and phenological stage, whereas relations were negative for C18:3n-3. The C18:1c9, C18:2n-6 concentrations were also positively related to growing degree days, rainfall, and herbage ADF content. Concerning milk, C18:3n-3 concentration was positively correlated to herbage DM content, whereas negatively to herbage crude protein (CP). The CLAc9t11 concentration was negatively correlated to herbage phenology. Branched-chain FA concentration was positively correlated to herbage DM, NDF, and ADF content and phenology, and negatively correlated to herbage CP and PUFA content