Feeding dairy cows the stems, seeds and skins from wine grapes boosts milk production and dramatically cuts the animal’s methane emissions, Australian researched published Thursday shows.

Scientists found that supplementing the cows’ feed with grape marc — the leftover material from wine-making — reduced cow emissions by 20 percent and increased milk production by five percent.

It also led to more healthy fatty acids in their milk, the research by Victoria’s Department of Primary Industries found.

Scientist Peter Moate said researchers were stunned by the results, with the cut to methane emissions thought to represent the largest reduction of its kind ever attained through the use of a feed supplement.

“We’ve managed to utilise what is currently a waste product for the wine industry and turn it into a very valuable feed source,” Moate said.

The scientists supplemented the diet of dairy cows with five kilograms of dried grape marc over 37 days and compared the results with other animals fed conventional fodder.