Succession patterns of the bacterial community in poultry litter after bird removal and sodium bisulfate application

Authors: JOHNSON, JASMINE - University Of Georgia; ZWIRZITZ, BENJAMIN - University Of Veterinary Medicine; Oladeinde, Adelumola - Ade; MILFORT, MARIE - University Of Georgia; Looft, Torey; CHAI, LILONG - University Of Georgia; ZOCK, GREGORY - University Of Georgia; SOMMERS, MARLO - Orise Fellow; TUNIM, SUPANON - Khon Kaen University; AGGREY, SAMUEL - University Of Georgia

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2021
Publication Date: 6/15/2021
Citation: Johnson, J., Zwirzitz, B., Oladeinde, A.A., Milfort, M.C., Looft, T.P., Chai, L., Zock, G.S., Sommers, M., Tunim, S., Aggrey, S.E. 2021. Succession patterns of the bacterial community in poultry litter after bird removal and sodium bisulfate application. Journal of Environmental Quality. 50(4):923-933. https://doi.org/10.1002/jeq2.20248.
DOI: https://doi.org/10.1002/jeq2.20248

Interpretive Summary: Proper broiler chicken litter management between flocks i.e., downtime has become the recommended preharvest best management practice for "raised without antibiotics" and "no antibiotics ever" production programs. However, what constitutes responsibly managed litter remains subjective and it's commonly judged by the moisture level of the litter and the amount of ammonia emitted from it. Consequently, litter treatments that can aid in lower litter moisture and pH are likely to be adopted and encouraged e.g., topdressing reused litter with fresh pine shavings and application of acidifiers. In this study, we provide valuable information on the identity of the bacterial species present during downtime and how the process of topdressing and lowering litter pH affects their population dynamics. We found that adding sodium bisulfate to reused litter lowered litter pH and moisture and perturbed the bacterial community present on the top layer of topdressed litter. Our result supports other studies that have demonstrated that application of sodium bisulfate reduces the pH and ammonia levels in litter, and sheds new light on its impact on bacterial species present.

Technical Abstract: Sulfate based acid amendments are used for treating litter between broiler chicken flocks and during grow-out for in-house ammonia abatement. These amendments reduce litter pH and inhibit ammonia volatilization by converting ammonia into nonvolatile ammonium. Research on the effects of acid amendments on litter microbiota is limited and are usually done in microcosms,which do not replicate natural environments. In this study, we determined the changes in bacterial populations present in litter during downtime (period after a flock was removed and before new broiler chicks were placed) and 24 h before and after Poultry Litter Treatment® (PLT) application– a sodium bisulfate (NaHSO4) based amendment. We made use of DNA sequencing technologies to characterize the litter microbiota, elucidating microbial shifts in litter samples with respect to downtime, litter depth, and PLT® application. During downtime (~18 days), the litter microbiota was dominated by Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. PLT® affected the microbiota in the top layer (3 cm) of reused litter topdressed with fresh pine shavings and resulted in an increase in Escherichia spp. and Faecalibacterium spp., and a decrease in members of the phylum Acidobacteria. Furthermore, culturable E. coli decreased by 1.5 log units during downtime, but an increase was observed for topdressed litter after PLT® was applied. While the effect of acidifiers on ammonia reduction, bird performance and litter performance are well documented, its effect on litter bacteria is not well understood. Our results suggest that acidifiers may perturb litter bacteria when topdressed with fresh pine shavings and requires further research.