Effects of high -concentrate diet supplemented with grape seed proanthocyanidins on growth performance, liver function, meat quality, and antioxidant activity in finishing lambs

•Supplementation of grape seed proanthocyanidins at levels of 10 and 20 mg/kg BW/day improved growth performance.•The Warner–Bratzler shear force of longissimus dorsi muscle linearly decreased with increasing grape seed proanthocyanidins addition.•Supplementation of grape seed proanthocyanidins linearly increased antioxidative enzyme activities of longissimus dorsi muscle and improved liver function of lambs.