In broiler chicken houses, the litter that the birds are reared on is a unique ecosystem that can make or break a flock. Litter management can be a much debated question, but a new study from the University of Georgia and the USDA-Agricultural Research Service has found that the litter in broiler chicken houses plays an important role in the birds’ pre-harvest health.
Specifically, reusing litter instead of supplying fresh litter every time can help bolster the birds’ immune systems, according to the researchers from the university’s Department of Poultry Science and the U.S. National Poultry Research Center. The same study also showed that reusing litter may help prevent the transfer of antibiotic resistance among bacterial species.
“Similar to the way human breastmilk contains good bacteria that helps boost a human baby’s immune system, litter is the first bacteria that chicks encounter and it also boosts their immune system. Chickens raised on fresh litter only get the microbiome of the litter itself, which is mostly just wood shavings,” said the study’s lead author Adelumola Oladeinde, a research microbiologist with USNPRC and adjunct faculty in UGA’s College of Agricultural & Environmental Sciences.
According to the university, Oladeinde and his collaborators started by infecting the chickens used in the study with a strain of Salmonella that was not antibiotic-resistant. Some of those chickens were then raised on fresh litter while others were raised on reused litter — a mixture of wood shavings, feces, uric acid, feathers and chicken feed.
At the end of the study, chickens raised on reused litter had a lower Salmonella positivity rate (66%) compared to chickens raised on fresh litter (79%). Additionally, the researchers found that some of these Salmonella-infected chickens on fresh litter were infected with a multi-drug resistant strain of Salmonella, while they found no multi-drug resistant Salmonella in chickens on reused litter.
This was particularly intriguing because the Salmonella strain the researchers used for the initial infection was not a multi-drug resistant strain. After investigating further, they discovered that this resistance was transferred from E. coli bacteria living within the chickens’ digestive systems.
The research shows that reusing litter can play a vital role in poultry health, as well as controlling the spread of antibiotic-resistant foodborne bacteria.
Reusing litter is also a cost-saving measure for the poultry industry to not have to buy fresh litter for every flock.
“There is a notion that reusing litter to raise multiple flocks of chickens can only be bad, which has hampered the widespread adoption of litter reuse. These contradictory attitudes towards litter recycling show that we need more research focused on poultry litter,” Oladeinde said.
However, recycling litter can lead to the accumulation of high ammonia levels in broiler houses, which can affect workers’ health, the university said. Industry practice when reusing litter in the U.S. is for poultry house owners to change out the litter after at least one year, or six flocks — but some poultry houses have been reusing litter for more than a decade with no issues.
While reusing litter over multiple broiler flocks is common in the U.S. and Brazil — two major poultry-producing countries — Canada recommends fresh litter for every flock, and some European countries have banned reusing litter altogether.
Arguments for reusing litter in poultry houses typically center on cost and disposal issues, but the “probiotic effect” that used litter may play in the health of broiler chickens makes an attractive case for maintaining the litter pack in a house, especially if steps are taken to mitigate ammonia emissions.