The bedding under their feet contains the first bacteria chicks are exposed to. For that reason, reusing litter — which contains a mixture of wood shavings, feces, uric acid, feathers, and chicken feed — rather than supplying fresh bedding can help build up the birds’ immune systems.

Joint research between the University of Georgia and the U.S. National Poultry Research Center investigated the role that bacteria play in poultry health and food safety. Beyond improving the immunity in chicks, they found that reused litter may also help prevent the transfer of antibiotic resistance between bacterial species.

Chicks in the study were infected with a strain of salmonella that was not antibiotic resistant. Some of the animals were raised on fresh litter while others were housed on reused litter.

When the study was completed, chickens raised on reused litter had a lower salmonella positivity rate (66%) compared to the chickens raised on fresh litter (79%). It was also found that some of the chickens raised on fresh litter were infected with a multi-drug resistant strain of salmonella — not the strain used originally to infect the chicks. None of the chickens raised on reused litter were infected with that strain. Further investigation found that this resistance was transferred from E. coli bacteria living within the digestive system.

This study showed the role reused litter can play in both animal health and controlling the spread of antibiotic-resistant foodborne bacteria, the researchers noted. It can also be a cost savings. One negative aspect is that reused litter may cause high ammonia levels to accumulate in broiler houses, which can affect human health. For this reason, some farms change out the litter at least annually.

This article appeared in the February 2023 issue of Journal of Nutrient Management on page 19.

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