Winery Waste Could Help Reduce Antibiotic Use In Chicken Farming

Your Next Chicken Dinner Might Be Raised on Winery Leftovers Instead of Antibiotics

Every year, Americans eat roughly 100 pounds of chicken per person, and poultry producers have long relied on antibiotics to help keep flocks healthy and growing efficiently. Now, researchers say the leftover pulp from wine and grape juice production might offer a surprisingly effective way to keep chickens growing well with less reliance on antibiotic growth promoters.

A new study published in npj Biofilms and Microbiomes found that adding small amounts of grape pomace, the skins, seeds, stems, and peels left over after grapes are pressed, to broiler chicken feed helped counteract a diet-induced model of chronic low-grade gut inflammation, improved the birds’ growth, and produced results comparable to a commonly used antibiotic growth promoter. As the U.S. poultry industry faces growing pressure to move away from antibiotics amid rising concerns about drug-resistant bacteria, researchers are searching for practical, affordable alternatives.

Antibiotic resistance already costs an estimated more than $3.5 billion annually, according to the study. When farmers stop using antibiotic growth promoters, chickens can become more vulnerable to gut inflammation, which slows growth and cuts into meat production. Grape pomace, a byproduct produced in massive quantities by wineries and juice makers, could be part of the answer.

How Gut Health Shapes Chicken Growth

Researchers at Cornell University and Arizona State University studied 126 male broiler chickens divided into six groups. One group was fed a standard diet. The remaining five were switched to a diet containing 30% rice bran, a high-fiber ingredient validated as a model for triggering chronic low-grade gut inflammation. One of those inflamed groups received no further intervention, and another received zinc bacitracin, a commonly used antibiotic growth promoter. The final three received the same inflammatory diet topped with either plain grape pomace, grape pomace fermented with a bacteria called Lactobacillus casei, or grape pomace fermented with a yeast called Saccharomyces cerevisiae, all at a 0.5% inclusion rate.

Results from the high-fiber diet were prominent. Inflamed birds saw body weight gain drop dramatically and feed intake fall by more than a quarter compared to chickens on the standard diet. Breast muscle yield also shrank significantly. Gut inflammation appeared to redirect available energy away from growth and toward fighting internal stress, a costly tradeoff for both animal and farmer.

Grape Pomace Closes the Gap in Antibiotic-Free Chicken Farming

When grape pomace, plain or fermented, was added to the inflammatory diet, the birds bounced back substantially. By the end of the 42-day study, chickens receiving grape pomace showed improvements in body weight, weight gain, and feed efficiency broadly comparable to the antibiotic group, with at least a 14.4% improvement in body weight and at least a 30% improvement in weight gain versus birds on the inflammatory diet alone. Breast muscle yield in the fermented pomace groups was also restored to levels comparable to the standard, non-inflamed group.

Researchers also measured two inflammation-signaling proteins, TNF-α and IL-1β. Birds on the high-fiber diet alone showed elevated levels of both. Grape pomace and fermented grape pomace tended to push those levels back down, though the authors noted several of these results were trends rather than statistically confirmed findings, and that some mechanisms remain associative rather than definitively proven.

What Was Happening Inside the Birds’ Guts

To understand the mechanism, the team examined the bacterial communities in a digestive pouch called the cecum. Chickens on the inflammatory diet had a less balanced gut bacterial community; some groups appeared to dominate more than others rather than coexisting in proportion. Grape pomace and its fermented versions helped restore greater balance, and fermented grape pomace reduced populations of potentially problematic bacteria such as Clostridium and Klebsiella to levels similar to those in the antibiotic group.

Fermented grape pomace, particularly the Lactobacillus casei version, also drove higher production of butyrate, a short-chain fatty acid that intestinal cells use as fuel and that helps reduce inflammation. Researchers found that beneficial bacteria, butyrate production, and reduced inflammation all tracked together with better growth, a chain of associations they flagged as promising but hypothesis-generating rather than proven cause and effect, noting the correlation analysis was not adjusted for multiple comparisons.

Grape Pomace Shows a Drug Resistance Advantage, Too

Grape pomace is currently agricultural waste. Repurposing it as a feed additive would cut disposal costs while potentially substituting a product that carries real public health risks when overused. One specific antibiotic resistance gene was significantly more elevated in the antibiotic group than in the grape pomace groups, a finding the researchers flagged as noteworthy but said requires further investigation. Fermented grape pomace may also offer microbe-driven benefits, though its probiotic or prebiotic role still needs more study before anyone can say so with confidence.

With antibiotic-free poultry programs expanding and drug resistance climbing, the industry needs practical alternatives that actually work. Based on this research, grape pomace, a byproduct most wineries currently discard, may have a serious role to play in keeping chickens healthy and growing efficiently, with less reliance on antibiotic growth promoters.

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Disclaimer: This article is based on a peer-reviewed study published in an academic journal. The research was conducted in a controlled laboratory setting and the findings should not be interpreted as established medical, veterinary, or agricultural guidance. Results may not reflect real-world farming conditions, and the authors themselves note that further research is needed before these findings can be applied commercially.

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