Wine is one of the most delicious agricultural products worldwide, but it leaves behind a less delectable trail: millions of tons of wasted skins, seeds, and flesh. Now a team of researchers has landed on a circular economy solution for these mounds of mush.
They say it can be used as a replacement antibiotic on chicken farms, working almost as well as the real thing.
In the United States where the study was based, broiler farms—those that raise chickens for meat—have been trying to wean their livestock off antibiotics, over growing fears about drug resistance and environmental damage. But there’s a catch: these drugs, known as ‘antibiotic growth promoters’ serve a useful purpose because they help fight harmful gut bacteria that cause inflamed guts, make chickens sick, and reduce their growth levels. Farmers have been crying out for a solution—and this is where wine waste comes in.
Building on previous work revealing the possible bacteria-fighting potential of wine waste (known as ‘pomace’), the researchers decided to test it out in a series of experiments on 126 chickens, which they split into different treatment groups. Some were fed a diet containing 30% rice bran which is a known gut-inflamer. Others received that diet, but with the addition of a conventional antibiotic called zinc-bacitracin. Another group were fed the bran diet supplemented with a tiny percentage of grape pomace, which was either plain or fermented.
Even at a tiny dose making up just 0.5% of the chickens’ diet, the researchers found that the addition of grape pomace brought about a remarkable change in the birds. Compared to those animals that received the diet without any added treatment, their body weight gains increased by 79%, and their average body weight increased by almost 20%, both helpful indicators of improved gut health.
The fermented grape waste produced the most promising results. The researchers think this may be because fermentation changes the grapes’ chemical composition in a way that appeals to beneficial gut microbes that can boost the chickens’ digestive health. Strikingly also, the grape waste-treated birds showed beneficial physiological changes in their guts,
Overall, the benefits of adding grape pomace were comparable to those recorded in the birds that received the conventional antibiotic treatment. It’s still not known why grape pomace has this antibiotic-like effect, but the researchers speculate that it could have something to do with a series of bioactive compounds contained in the waste including flavonoids, polyphenols, and tannins, which have been shown to reduce inflammation and to have antibacterial qualities. All of that potential sits untapped in wine waste, like buried treasure.
But at least now there’s a possible alternative. Fermentation to make wine, and then to treat chickens might be exactly the circular solution that both these industries need.
Tako et. al. “Dietary grape pomace mitigates high-NSP-induced inflammation and production loss via microbiome-SCFA-immune mediated pathways.” npj Biofilms and Microbiomes. 2026.
Image: ©Anthropocene
