Meta-analysis of dietary supplementation with flavonoids in small ruminants: Growth performance, antioxidant status, nutrient digestibility, ruminal fermentation, and meat quality

This study aimed to evaluate the effects of dietary supplementation with flavonoids on growth performance, antioxidant status, nutrient digestibility, ruminal fermentation, and meat quality of small ruminants through a meta-analytic approach. The data used in the meta-analysis were extracted from 29 scientific articles identified through systematic searches following the PRISMA methodology. Der-Simonian and Laird, random effects models, were used to assess effect sizes using weighted mean differences. Dietary supplementation with flavonoids increased (P < 0.05) dry matter intake, average daily gain, hot carcass weight, hot carcass yield, Longissimus dorsi muscle area, and backfat thickness. In contrast, the feed conversion ratio decreased (P < 0.05) in response to dietary flavonoid supplementation. Dietary supplementation with flavonoids increased (P < 0.001) the serum concentration of superoxide dismutase, catalase, glutathione peroxidase, and total antioxidant capacity but decreased (P < 0.001) the serum concentration of malondialdehyde (MDA). The digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber increased (P < 0.05) in response to dietary flavonoid supplementation. Dietary supplementation with flavonoids decreased (P < 0.001) the ruminal concentration of ammonia nitrogen and increased (P < 0.001) the ruminal concentration of total volatile fatty acids and acetate. Dietary supplementation with flavonoids decreased (P < 0.001) cooking loss, shear force, and MDA in meat. In conclusion, dietary supplementation with flavonoids can be used as a nutritional strategy to improve growth performance, antioxidant status in blood serum, nutrient digestibility, ruminal fermentation, and meat quality in small ruminants.