Early litter microbiota changes influence the development of footpad dermatitis in broilers challenged with Salmonella Infantis

Authors: Pokoo-Aikins, Anthony; CHUNG, TAEJUNG - Orise Fellow; Oladeinde, Adelumola; Read, Quentin; Adeli, Ardeshir; KWAKYE, JOSEPHINE - University Of Georgia; ARIYO, OLUWATOMIDE - University Of Georgia; FULLER, ALBERT - University Of Georgia; GHAREEB, AHMED - University Of Georgia; MILFORT, MARIE - University Of Georgia; Plumblee Lawrence, Jodie; HAMAOKA, TOMOHIRO - Asahi Biosciences; Rothrock Jr, Michael; AGGREY, SAMUEL - University Of Georgia

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2026
Publication Date: 9/15/2026
Citation: Pokoo-Aikins, A., Chung, T., Oladeinde, A.A., Read, Q.D., Adeli, A., Kwakye, J., Ariyo, O., Fuller, A.L., Ghareeb, A.F., Milfort, M.C., Plumblee Lawrence, J.R., Hamaoka, T., Rothrock Jr, M.J., Aggrey, S.E. 2026. Early litter microbiota changes influence the development of footpad dermatitis in broilers challenged with Salmonella Infantis. Avian Diseases. https://doi.org/10.1637/aviandiseases-D-26-00025.
DOI: https://doi.org/10.1637/aviandiseases-D-26-00025

Interpretive Summary: Footpad dermatitis (FPD) is a common problem in broiler chickens that affects their welfare, health and farm profits. It is often linked to wet litter, but there is limited information on how foodborne pathogens and early litter microbiome impacts paw health. In this study, we looked at footpad lesions in Cobb 500 broilers at 49 days and measured litter conditions and bacteria during the grow-out period. Birds were placed in four groups: a Negative Control, Positive Control challenged with Salmonella Infantis, a group given a feed probiotic (Calsporin®) plus challenge, and a group raised on litter applied probiotic (proLitterbiotic) plus challenge. Lesion scores were slightly different among groups, with the Positive Control and proLitterbiotic birds more likely to have severe lesions than the Calsporin and Negative Control birds. Litter moisture, pH, and metal levels changed over time but didn’t clearly match lesion severity. Female birds in the Positive Control and proLitterbiotic groups were heavier later in the grow-out. DNA sequencing showed that litter bacteria changed mostly over time, but early differences in treatment were clear a few hours after broilers were challenged with Salmonella Infantis. These early changes matched later differences in paw health. Overall, poor paw quality was linked to early litter bacteria, bird weight, and litter differences.

Technical Abstract: Footpad dermatitis (FPD) is a common welfare and economic concern in broiler production and it is closely linked to litter conditions and bird performance. While wet litter is a well-recognized risk factor, the contribution of early litter microbiome to paw quality remains poorly understood. In this study, we evaluated footpad lesion severity in Cobb 500 broilers at harvest (49 days) and examined litter microbiological and physicochemical parameters throughout grow-out to identify factors associated with differences in paw quality. Birds were raised under four treatments: a Negative Control, a Positive Control challenged with Salmonella enterica serovar Infantis (S. Infantis), a feed-applied Bacillus velezensis probiotic (Calsporin®) with S. Infantis challenge, and a litter-applied B. velezensis probiotic (proLitterbiotic) with S. Infantis challenge. Footpad lesion scores differed modestly among treatments, with the Positive Control and birds receiving proLitterbiotic exhibiting a higher probability of severe lesions at harvest compared with Calsporin and Negative Control birds. Litter moisture, water activity, pH, and metal composition varied by treatment at select time points but did not consistently align with lesion severity. Female birds in the Positive Control and proLitterbiotic treatments had higher body weights during mid-to-late grow-out. 16S rRNA gene sequencing revealed that litter bacterial communities were strongly structured by time and showed treatment-associated differences immediately after placement. Early litter bacterial communities reflected contributions from broiler house environment and starter feed, with distinct separation between treatments receiving litter-applied probiotics and those receiving feed-applied probiotics. Although litter microbial communities converged later in the grow-out, early differences coincided with subsequent variation in paw quality. These findings indicate that poorer paw quality was associated with a combination of early changes in litter microbial community, body weight, and transient litter physicochemical differences, rather than a single dominant factor.