Compositional differences of milk from pasture-based systems compared with systems consuming large amounts of non-pasture feeds.

Pasture-based milk production systems represent a considerable minority from a global perspective but encompass unique management factors, which lead to characteristic differences in milk composition relative to conventional production systems. Synchronized calving patterns, associated stage of lactation effects and coincident variation in dietary composition throughout the year contribute to seasonal changes across a range of compositional factors from early transition milk to mid-lactation and late-lactation milk. The most substantial and identifiable impacts of pasture-based production are resolved in the fatty acid profile of milk; however, considerable shifts in gross compositional factors, nitrogen composition, mineral and vitamin profiles, and minor volatile compounds and metabolites also present seasonal trends and notable changes in concentration in response to grass feeding.