Byproducts of winemaking offer a viable substitute for antibiotics in poultry cultivation. Merely incorporating half a percent of grape pomace into the feed of broilers suffering from chronic intestinal inflammation successfully restored bird growth, suppressed harmful bacteria, and enhanced meat quality. Unlike conventional growth promoters, pomace does not encourage the development of superbugs, presenting the industry with an economical and environmentally friendly alternative.
Globally, the agricultural sector is progressively phasing out antibiotics used as growth stimulants due to the risk associated with the emergence of drug-resistant microorganisms. Without these medications, however, farmed poultry are more susceptible to chronic gut inflammation, experience weight loss, and use feed inefficiently. An ideal replacement must mitigate inflammation while promoting animal growth without adverse side effects.
The researchers, whose findings were published in the journal npj Biofilms and Microbiomes, opted to utilize grape pomace—a waste product from wine and juice production that can constitute up to 20% of the processed grape mass—instead of antibiotics. This material is rich in fiber, antioxidants, and polyphenols, yet in practical settings, it frequently ends up decomposing in landfills.
To assess the efficacy of the pomace, scientists from Cornell University conducted an experiment involving 126 broiler chickens. To mimic the challenges found on commercial poultry farms, the animals were intentionally given a harsh diet to induce chronic intestinal inflammation. This diet involved supplementing their feed with 30% rice bran, which is high in non-starch polysaccharides.
Subsequently, the birds were divided into six different groups. The first group received a standard diet. The second group followed only the challenging diet, while the third group received the harsh diet supplemented with a commonly used feed antibiotic, zinc bacitracin. The final three groups were fed the non-antibiotic feed but included 0.5% grape pomace—which was either standard, fermented with lactic acid bacteria, or fermented with yeast. Over a 42-day period, the scientists monitored weight gain, analyzed blood composition, examined the cecal microbiome, and assessed gene activity within the birds’ intestines.
The rigorous diet caused severe inflammation and a 54% reduction in weight gain. Nevertheless, the grape pomace nearly entirely offset these setbacks; the birds grew just as well as the broilers treated with antibiotics. Chickens consuming the grape-supplemented diet exhibited lower expression of inflammatory genes (IL-1β and TNF-α), and the villi—structures responsible for nutrient absorption in the gut—became noticeably larger.
The pomace acted as a prebiotic, fundamentally altering the birds’ microbiome profile. Broilers saw a sharp decline in pathogens such as Clostridium and Klebsiella, alongside an increase in beneficial bacteria populations like Monoglobus and Lactobacillaceae. The pomace treated with lactic acid bacteria proved particularly effective, stimulating the production of substantial amounts of butyric (butyrate) and propionic acids. These molecules serve as the primary energy source for intestinal cells and actively suppress inflammation.
The most significant distinction between the dietary regimens emerged when analyzing droppings for antibiotic resistance genes. The group receiving zinc bacitracin showed the anticipated surge in the resistance gene bcrA. In contrast, no such genes were detected in the poultry fed the pomace: the supplement achieved the same commercial outcome in terms of weight accrual without introducing the risk of creating superbugs.
The researchers are presenting an economically advantageous solution to the problem of antibiotic resistance within agribusiness. Utilizing bioactive winery byproducts as a functional feed additive can help improve poultry health while simultaneously reducing the environmental burden on the ecosystem.
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