Condensed tannins as antioxidants in ruminants : effectiveness and action mechanisms to improve animal antioxidant status and oxidative stability of products
Agriculture ; Veterinary Sciences ; ZoologyCondensed tannins (CTs) are widely distributed in plants, and due to their recognized
antioxidant activity are considered as possible natural antioxidants for application in ruminant
diets. A wide range of CT-rich sources has been tested in ruminant diets, and their effects on
animal antioxidant status and oxidative stability of their products are reviewed in the present work.
Possible mechanisms underlying the CT antioxidant effects in ruminants are also discussed, and
the CT chemical structure is briefly presented. Utilization of CT-rich sources in ruminant feeding
can improve the animals’ antioxidant status and oxidative stability of their products. However,
the results are still inconsistent. Although poorly understood, the evidence suggests that CTs can
induce an antioxidant effect in living animals and in their products through direct and indirect
mechanisms, which can occur by an integrated and synergic way involving: (i) absorption of CTs
with low molecular weight or metabolites, despite CTs’ poor bioavailability; (ii) antioxidant action on
the gastrointestinal tract; and (iii) interaction with other antioxidant agents. Condensed tannins are
alternative dietary antioxidants for ruminants, but further studies should be carried out to elucidate
the mechanism underlying the antioxidant activity of each CT source to design effective antioxidant
strategies based on the use of CTs in ruminant diets.info:eu-repo/semantics/publishedVersio