Alpine vegetation type affects composition of nutritionally important C18 fatty acids in tissues of lambs from different breeds

Summary

A total of 110 lambs of the breeds Engadine Sheep and Valaisian Black Nose Sheep were fattened on one lowland and three different alpine pasture types. The experiment was conducted in two consecutive years and lasted for 9 weeks of grazing in each year. Immediately afterwards, the lambs were slaughtered.
Perirenal adipose tissue and the Longissimus dorsi muscle were analysed for fatty acid composition. The lambs on the lowland pasture had the lowest proportions of linoleic and α-linolenic acid in the lipid fraction of these tissues. Additionally, there was a clear differentiation in these proportions when lambs grazed different alpine vegetation types. This was related to the content of phenolic compounds rather than the fatty acid contents of the swards, and an increasing phenolic level probably resulted in a higher ruminal protection of the native plant fatty acids. Intermediates of biohydrogenation (vaccenic acid and conjugated linoleic acid) were highest in the lowland lambs. Animal breed effects were weak.