Effect of free-range feeding on n−3 fatty acid and α-tocopherol content and oxidative stability of eggs

This study was carried out to compare the fatty acid and α-tocopherol composition and the susceptibility to oxidation of egg yolks from hens fed grass and a commercial mixed diet under free-range conditions or in cages with only the commercial diet. Grass had a relative high proportion of α-linolenic acid (534 g kg−1 total fatty acids) and α-tocopherol (162.3 mg kg−1 DM). Eggs from hens fed under free-range conditions had a higher concentration of total (n−3) fatty acids than eggs from hens fed the commercial diet (P<0.05). Eggs from layers on free-range had a higher concentration of α-tocopherol than those of hens maintained in cages and fed the commercial diet (P<0.01). No differences in initial values or rate of oxidation were observed between treatments. This research suggests that some constituents of grass may be of interest for the production of eggs rich in (n−3) fatty acids, without adverse oxidative effects.