Study finds that reusing chicken litter can deter Salmonella growth

Grace Connatser
Wisconsin State Farmer
A study produced by the USDA says reusing chicken litter can deter Salmonella growth, rather than encourage it.

A new research study from the US Department of Agriculture says that reusing broiler chicken litter can deter Salmonella bacterial growth, rather than encourage it, according to a press release.

Adelumola Oladeinde, a co-author of the study and researcher at the USDA's National Poultry Research Center, said the study disproves health and safety concerns surrounding the reuse and recycling of broiler litter. The "good" bacteria in the litter actually hinders the growth of bad bacteria, like Salmonella, he explained.

"It may be worthwhile to invest time and resources to characterize the bacteria in reused litter," Oladeinde said. "We can develop the promising ones into beneficial microbes for better chicken gut health."

The study took samples of reused broiler litter from the University of Georgia Poultry Research Center and used it to raise three different flocks of chickens. Salmonella was added to each litter batch, and the presence and growth of microbes were evaluated. Some microbes, like Nocardiopsis, known for its production of toxins and antibiotics, seemed to reduce the growth of Salmonella.

The study looked at different characteristics of reused broiler litter, such as ammonia and moisture levels. Different levels of these components can affect the growth of different bacteria, fungi and viruses, the press release said. This is important because broiler chickens spend so much time living on litter and pecking from it – up to several weeks.

Oladeinde said producers should wait before reusing old chicken litter, though. He found that the optimal litter downtime was two weeks.

"For farmers, a shorter downtime will result in growing more birds through the year," Oladeinde said. "We showed that the reused litter after two weeks of downtime had a microbiome that was unfavorable to Salmonella."

Chicks often begin eating from the litter before they eat from feeding troughs or drink water, so the bacteria, fungi and viruses contained in their litter are what determine their gut health as they grow. Salmonella can be found in marketed chicken products because of what chickens eat. 

The CDC reported 11 different Salmonella outbreaks in 2019 alone, coming from all sorts of food sources, with one of them being backyard poultry. The outbreak, which stretched from January to October, included 13 strains of the bacteria. Over a thousand people became sick with salmonellosis in 49 states, with 219 hospitalizations and two deaths.

"These first microbes play a key role in determining gut health," Oladeinde said "Therefore, it is critical to determine what a beneficial litter microbiome looks like."