The Action Potential of Antioxidant Grape Seed Proanthocyanidin as a Rumen Modifier to Mitigate Rumen Methanogenesis In Vitro

Grape seed proanthocyanidin (GSP) contains polyphenolic bioflavonoids ubiquitously found in the lignified portions of grape seeds from the winery and distillery industries, as an antioxidant. To explore its potential as a rumen modifier in methanogenesis inhibition, a 2 × 5 factorial experiment was conducted to determine the effect of GSP at 0, 15, 30, 60 and 120 mg/g of substrate on the rumen fermentation and methanogenesis of two representative total mixed rations (HY, a diet for high-yield (>2 kg/d) lactating cows, and LY, a diet for low-yield (72.5%), followed by Methanomassiliicoccus (>20.9%) and Methanosphaera (>1.0%). Methanobrevibacter could play an important role in methanogenesis in the presence of GSP, though it is usually considered to be the main hydrogenotrophic methanogen. In brief, the GSP addition presented high potential as a rumen modifier to mitigate methanogenesis by decreasing the ratio of methanogens to total bacteria. Methanobrevibacter could play an important role in methanogenesis in the presence of GSP. However, a relatively low administration level of GSP should be taken into consideration in order to obtain its inhibitory effect on CH4 emission, with a minimal negative effect on rumen digestion and fermentation.