RT Journal Article T1 Addition of fermented and unfermented grape skin in broilers’ diets: effect on digestion, growth performance, intestinal microbiota and oxidative stability of meat A1 Nardoia, María A1 Romero, Carlos A1 Brenes, Agustín A1 Arija Martín, Ignacio A1 Viveros Montoro, Agustín A1 Ruiz Capillas, C. A1 Chamorro Francisco, Susana AB Grape skin is a source of polyphenols with antioxidant and antimicrobial properties. Little information is available regarding its application in animal feeding. The present study investigated the effect of inclusion of fermented (FS) and unfermented (UFS) grape skin at two different doses (30 g/kg, FS30 and UFS30, and 60 g/kg, FS60 and UFS60) and 200 mg/kg vitamin E (α-tocopheryl acetate) in a corn–soybean diet on growth performance, ileal protein digestibility, ileal and excreta total extractable polyphenols content and digestibility, intestinal microbiota and thigh meat oxidation in broiler chickens. Growth performance was depressed in chickens fed UFS and FS diets. A reduction in ileal protein digestibility was also observed in birds fed UFS, being this effect more pronounced in those fed 60 g/kg. The dietary inclusion of grape skin increased both ileal and excreta polyphenols contents, being higher in birds fed UFS than in those fed FS. Excreta moisture content increased in birds fed UFS and FS diets. No effect of dietary inclusion of grape skin was observed on ileal counts of lactic-acid bacteria and Clostridium, but UFS inclusion in the diet reduced ileal count of Escherichia coli as compared with FS dietary inclusion. After 7 days of refrigerated storage, values of thiobarbituric acid reactive substances (TBARS) were lower in chicken meat when grape skin was added in the diet at 60 g/kg instead of 30 g/kg, and meat from birds fed 60 g/kg of grape skin reached TBARS values similar to those of birds supplemented with vitamin E. In conclusion, high doses of grape skin polyphenols depressed growth performance and protein digestibility, and increased excreta moisture content. Unfermented grape skin contained more polyphenols than FS, and its inclusion in the diet led to higher ileal and excreta polyphenols contents and to a lower ileal count of E. coli. Furthermore, the antioxidant potential of the polyphenols present in grape skin was observed after 7 days of meat storage, with the dose of 60 g/kg of grape skin being as effective as vitamin E supplementation in maintaining oxidative stability of meat. PB Elsevier SN 1751-7311 YR 2020 FD 2020 LK https://hdl.handle.net/20.500.14352/109753 UL https://hdl.handle.net/20.500.14352/109753 LA eng NO Nardoia M, Romero C, Brenes A, Arija I, Viveros A, Ruiz-Capillas C, Chamorro S. Addition of fermented and unfermented grape skin in broilers’ diets: effect on digestion, growth performance, intestinal microbiota and oxidative stability of meat. Animal 2020;14:1371–81. https://doi.org/10.1017/S1751731119002933. NO Ministerio de Economía (España) NO Comunidad de Madrid NO Junta de Castilla y León NO Ministero dell'Istruzione, dell'Università e della Ricerca NO Università del Molise DS Docta Complutense RD 13 abr 2025