Effects of antioxidant capacity-based dietary replacement of vitamin E with commercial products containing grape skin-green tea extracts or hydrolyzed wood polyphenols on poultry performance, metabolism, immune-related gene expression, and meat quality

Natural antioxidants are widely investigated as potential substitutes for synthetic compounds suitable for use in organic diets. They are often included in diets based on literature and manufacturer recommendations, sometimes leading to inconsistent results. In this study, we replaced 0.05 g/kg of vitamin E in poultry diets (vitE) with commercial products containing grape skin and green tea extracts (GSGT) or hydrolyzed wood polyphenols (HWP), at doses calculated based on their in vitro antioxidant capacity measured by the 2.2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) test (ABTS). A total of 252 one-day-old male Ross 308 chicks, reared according to organic farming guidelines, were assigned to 9 pens in a randomized block design with 3 replicates per dietary treatment; 108 were slaughtered at 42 days as in the conventional production cycle, while the remaining were slaughtered at 84 days, in accordance with organic farming regulations. Overall, no differences were observed in ...