Seasonal variation of fatty acid composition in Swiss mountain's milk

The influence of typical feeds in the five mountain regions Engadin, Rheinwald, Emmental, Luzerner Hinterland and Toggenburg on the fatty acid (FA) compostion of milkfat was investigated over one year from May 2004 till April 2005. The average attitude of grass-based feed (GBF) growth was 1247 +/- 465 in for the summer feed and 1136 +/- 310 in for winter feed. Compared to winter, summer milk had a significantly lower concentration of saturated FA (SFA) (-8.6 %) and significantly higher contents of mono-unsaturated FA (MUFA) (+19.9 %), poly-unsaturated FA (PUFA) (+21.7 %), conjugated linoleic acid (CLA) (+70.1 %), and trans FA without CLA (+56.7 %). Summer and winter milk from mountains did not significantly differ with respect to the contents of n-3 and n-6 FA. However, the content of the main n-3 FA (alpha-linolenic acid) was significantly higher in summer milk and its content was positively correlated with increasing percentages of GBF and altitude. According to Swiss food law regulations, the commercialisation of the nutrional advantages of mountain milk is not possible at the moment.