Grape marc (the skins, seeds, stalk, and stems remaining after grapes have been pressed to make wine) is currently a by-product used as a feed supplement by the dairy and beef industries. Grape marc contains condensed tannins and has high concentrations of crude fat; both these substances can reduce enteric methane (CH4) production when fed to ruminants. This experiment examined the effects of dietary supplementation with either dried, pelleted grape marc or ensiled grape marc on yield and composition of milk, enteric CH4 emissions, and ruminal microbiota in dairy cows.
Methane (CH4) is a potent greenhouse gas. Enteric CH4 emissions from ruminants amount to approximately 80 million tonnes annually and account for approximately 28% of global anthropomorphic CH4 emissions. Interest is growing in developing practical nutritional strategies for ruminants that will reduce these emissions.
One strategy that can reduce CH4 emissions is the addition of fat to the diet of ruminants. Another effective strategy
for reducing enteric CH4 emissions from ruminants involves including condensed tannins (CT) in their diet.