A Novel Feed Additive Derived from Mushroom-Based Phytonutrients: Effects on Rumen Antioxidant Capacity, Fermentation, and Methane Production

Mushrooms are considered a significant source of antioxidants, antimicrobials, and phytonutrients. Consequently, they can serve as a phytogenic feed additive to prevent oxidative stress, while improving rumen fermentation efficiency. The aim of the present investigation was to evaluate the effects of bolete mushroom extract (BME) supplementation on in vitro digestive enzymes, nutrient degradability, antioxidant capacity, rumen fermentation, and methane production. In a completely randomized design, six treatment levels of BME were implemented. The total dry matter (DM) substrate of BME was supplemented at 0%, 1%, 2%, 3%, 4%, and 5%. The results demonstrated that BME increased the activity of digestive enzymes, particularly amylase activity and in vitro dry matter degradability. Importantly, at 4% of the total DM substrate, BME significantly increased levels of total antioxidant and catalase activity, while malondialdehyde activity was reduced. BME addition contributed to an increase in propionate and total volatile fatty acid production, while methane production was decreased. As a result, BME could be effective as a sustainable feed additive comprising phytonutrients to enhance rumen fermentation and reduce methane emissions in ruminants.