Fatty acid profile, secondary compounds and antioxidant activities in the fresh forage, hay and silage of sainfoin ( Onobrychis viciifolia ) and sulla ( Hedysarum coronarium )

BACKGROUND: Sainfoin (Onobrychis viciifolia) and sulla (Hedysarum coronarium) are forage legumes usually preserved to optimize their utilization as feedstuffs. However, the method of preservation modifies the chemical composition differently in both legume species. Secondary compounds (such as proanthocyanidins, fatty acids, carotenoids and tocopherols) present in forages affect the quality of animal products. Therefore, the effect of preservation on the contents of secondary compounds should be investigated. Accoridngly, samples of sainfoin and sulla were directly freeze‐dried (fresh), dried at ambient temperature (hay) and vacuum‐packaged for 82 days (silage). RESULTS: In both legumes, the total fatty acid and C18:3 n‐3 contents decreased and C16:0 increased with preservation (P < 0.001), with a greater effect for the hays than for the silages. For both legumes, the lutein, neoxanthin and violaxanthin contents decreased to a greater extent in the silages than in the hays (P < 0.001). Both hays exhibited the lowest β‐carotene concentrations (P < 0.001). The α‐tocopherol contents decreased in hays, but not in silages, compared to the fresh forages of both legumes (P < 0.001). The antioxidant activities were lower in the silages than in the hays and fresh forages (P < 0.001) and were very strongly related to the contents of polyphenols and proanthocyanidins (P < 0.001). CONCLUSION: Haymaking affected the fatty acid, carotenoid and α‐tocopherol contents to a greater extent but had a lesser effect on the antioxidant activities than silage‐making, which were very strongly related to their contents of polyphenols and proanthocyanidins. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.