Chicken consumption has doubled in the U.S. since 1980, breezing past beef in 2010. But nearly three-quarters of production costs in the industry are bound up in what the birds eat.
Spent grain from the brewing industry offers a huge opportunity for animal agriculture, with about 36.4 million tons produced as waste annually. Brewers' spent grain (BSG) is frequently upcycled and used as cattle and hog feed, but chickens cannot efficiently digest such fiber-rich ingredients.
In a paper, "Intestinal Effects of Brewers' Spent Grain Extract in Ovo," appearing in a special issue of the journal Animals, three Cornell researchers explored how to optimize spent grain as a sustainable dietary ingredient with gut health and nutritional benefits for broiler chickens.
The researchers turned to the water-soluble fraction of brewers' spent grain, making an extract without the grain's protein and dietary fiber, which can limit nutrient absorption. They used this extract to determine effects on broiler chickens' gut development, function and microbial populations.
The corresponding author is Elad Tako, associate professor in the Department of Food Science in the College of Agriculture and Life Sciences. Co-authors are Melissa Huang, doctoral student in the field of food science, and Louisa Smieska, a project scientist at the Cornell High Energy Synchrotron Source (CHESS), where synchrotron X-ray imaging of the intestinal tracts of embryonic chickens was conducted.
BSG contains a variety of compounds known for their immune-regulatory, anti-microbial and antioxidative benefits. They found the extract improved development of the small intestine and decreased the presence of potentially harmful bacteria like E. coli and Clostridium. This is promising because the poultry industry is mandated to keep harmful bacteria out of meat while reducing reliance on antibiotic use.
"We were also able to detect iron and zinc via synchrotron x-ray imaging in the small intestinal tissue samples post-treatment," Tako said, adding that both are essential for growth.
With the global poultry feed market projected to reach $238.9 billion by the end of 2025, the broiler feed industry could benefit from a nutritionally advantageous ingredient that also happens to be more affordable because it comes from a waste stream, he said. Tako said that from a consumer perspective, many sustainability-minded shoppers prize foods that find new purposes for ingredients that might otherwise have gone to a landfill.
They made their extract from spent grain sourced from Harpoon Brewery in Boston. Using a method called "intra-amniotic administration" by which a substance is directly injected into the amniotic sac inside of eggs, they essentially "fed" 36 Cornish Cross broiler embryos through the natural amniotic fluid to determine precise gut health effects. The eggs were then incubated and the intestinal tracts of the broiler embryos examined.
"One thing in this study that had never been done before was because of our collaboration with CHESS," Tako said. "We reached out to our co-author, Louisa Smieska, and she said they had previously used this technique to look into mineral distribution. She said it could be adapted to look at the content and distribution of iron and zinc in the tissue."
Synchrotron X-ray imaging could be an exciting and powerful new technique to measure mineral status in biological samples, he said.
According to Huang, the results demonstrate a benefit that supports longer-term studies with adult birds or other animals. She says the team's next study involves the use of upcycled grape pomace, the solid waste product from the winemaking process, which is also believed to have anti-inflammatory properties.
Since the start of the avian flu outbreak in 2022, more than 82 million birds - around 22% of the American poultry flock - have been culled. And while it affects laying hens more frequently than broiler chickens, all poultry farmers are focused on prevention and prioritizing flock health.
"The poultry industry is always looking for ways to optimize the way they raise their flock," Huang said. "And along with a rising demand for chicken, there is an incentive to look at upcycled products to incorporate into a circular economy that minimizes waste."
