Effects of increasing doses of red yeast rice polyphenol extract on apparent digestibility, antioxidant activity, milk production, and fatty acid in lactating dairy goats

The effects on the apparent digestibility, antioxidant activity, milk production, component, and fatty acid (FA) profiles were evaluated in dairy goats fed a varying red yeast rice polyphenol extract (RYRE) content. Thirty-two dairy goats were randomly allocated into 4 treatments. The goats were fed a basal diet (CON) or a diet supplemented with 1, 2, or 3 g/kg of RYRE. The results indicated that apparent digestibility of neutral detergent fiber and acid detergent fiber was significantly affected by treatments, and increased linearly and quadratically with increasing RYRE supplementation (P < 0.05). The total antioxidant capacity, glutathione peroxidase, and catalase increased quadratically, and the malondialdehyde concentration decreased quadratically with increasing RYRE content (P < 0.05). The milk production parameters and n-3 polyunsaturated fatty acids (PUFAs) increased linearly and quadratically (P < 0.05) with increasing RYRE supplementation. The L* value and n6/n3 ratio decreased linearly and quadratically, and the a* value and milk lactose increased quadratically with increasing RYRE supplementation (P < 0.05). The total volatile fatty acid and propionic acid increased quadratically, whereas the acetic acid and acetate:propionate ratio decreased quadratically with increasing RYRE supplementation. Overall, diets supplemented with RYRE enhance apparent digestibility, antioxidant activity, promote milk production, increase milk n-3 PUFAs, and improve rumen fermentation of lactating dairy goats, with the 2 g/kg RYRE treatment having the optimal effects under the conditions of this experiment.