Effect of dietary grape pomace on growth performance, meat quality and antioxidant activity in ram lambs

Wine grape pomace (WGP) provides a rich source of polyphenols that can act as powerful antioxidants, but their potential as feed ingredients in the lamb industry remains unexploited. The objective of this study was to investigate the effect of dietary WGP supplementation on growth performance, meat quality and antioxidative activity in the longissimus dorsi (LD) muscle of lambs. A total of eighteen lambs (25.0 ± 0.2 kg of body weight, BW) were randomly selected and equally divided into three groups, and offered diet containing different levels of WGP (0%, 5% and 10%). The results showed that supplementation with 10% dietary WGP increased body weight, average daily gain, and reduced the feed to gain ratio (P < 0.05). There was no observed effect of dietary WGP supplementation on pH, color, cooking loss, or intramuscular fat (IMF). Lambs fed with a WGP-containing diet had lower Warner-Bratzler shear force (WBSF) (P < 0.05), and a decreased collagen content (P < 0.05). The total antioxidative capacity (T-AOC), glutathione peroxidase 4 (GPx4) and superoxide dismutase (SOD) activity were increased when lambs were fed the WGP-containing diet (P < 0.05), whereas no difference in catalase activity was detected. In addition, WGP supplementation decreased ROS and MDA levels induced in animals raised in penned conditions (P < 0.05). Taken together, these results suggest that WGP can be used as a feed ingredient in lamb production to relieve oxidative stress, and improve feed efficiency and meat tenderness, possibly due to the enhanced antioxidative capacity.