Variation of fatty acid composition of forage from natural pasture located at different altitudes during the first growth cycle.

Milk produced from cows on highland pastures contains more fatty acid (FA) with properties beneficial to human health, such as conjugated linoleic acid (CLA) and polyunsaturated FA (PUFA). These FA are mainly derived from partial biohydrogenation of PUFA in the diet. The main objective of this research was to study the variability of forage FA profile over the period of the first growth cycle of permanent meadows at different altitudes. Permanent grasslands located at four different altitudes, 350, 1400, 1800 and 2200 m a.s.l., were studied. The first growth cycle of grasslands was sampled two times, in early and late stage of maturity, and analysed for botanical composition, dry matter (DM) yield and FA content. The results showed that altitude affects the botanical composition, DM yield and FA concentration of forage. Furthermore, the α-linolenic acid decreased with advancing maturity