Effects of heat stress and depressed feed intake on the cecal and ileal microbiota of broiler chickens

Authors: Campos, Philip; GREENE, ELIZABETH - University Of Arkansas; Proszkowiec-Wegla, Monika; DRIDI, SAMI - University Of Arkansas

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2025
Publication Date: 7/23/2025
Citation: Campos, P.M., Greene, E.S., Proszkowiec-Wegla, M.K., Dridi, S. 2025. Effects of heat stress and depressed feed intake on the cecal and ileal microbiota of broiler chickens. Scientific Reports. Volume 104, Issue 10. https://doi.org/10.1016/j.psj.2025.105591.
DOI: https://doi.org/10.1016/j.psj.2025.105591

Interpretive Summary: Modern broiler chickens have become more susceptible to environmental challenges such as heat stress after multiple decades of breeding for traits such as faster growth and higher breast yield. The stress can harm gut integrity and lead to poor health and reduced growth rates. Heat stress can also decrease the chickens’ appetite resulting in decreased feed intake. The goal of this study was to distinguish between effects of heat stress and decreased feed intake on gut microbes, and to investigate whether only two hours exposure to heat stress (acute heat stress) could affect the gut microbes in the same way chronic heat stress affects gut microbes. We have determined that chicken gut microbes react differently to heat stress than to decreased feed intake, and that chronic heat stress affects gut microbiota differently than acute heat stress. These findings may help scientists and producers devise better nutritional strategies to maintain gut microbial balance and attenuate the negative effects of heat stress on broiler chickens.

Technical Abstract: Chronic heat stress (HS) is known to depress feed intake (FI) and growth in broiler chickens, and may alter the gut microbiota and health, however, the amplitude and duration of each (HS and depressed FI) effect on gut microbiota is still unclear. This study aimed to determine the effects of chronic and acute HS on the cecal and ileal microbiota profiles. Broilers were subjected to thermoneutral (TN, 23 °C) or chronic cyclic HS (CHS, 8 h/d, 35 °C) condition from d29-42, and one group to acute HS (AHS, 2 h, 35 °C) at d42. To distinguish between the effect of HS and FI, one pair-fed (PF) group (maintained at TN condition but had similar FI as CHS birds) was used from d29-42. Chronic HS decreased richness in the cecal microbiota compared to TN, while PF did not, and AHS led to higher richness compared to CHS. Acute HS and PF altered cecal microbiota profiles similarly to CHS when weighted for bacterial abundances. In the ileum, PF altered microbiota based on presence and absence of taxa, and CHS further altered microbiota. Treatments affected bacterial taxa differently, however, all treatments decreased Lactobacillus while increasing Ligilactobacillus in the cecum. Predicted functional abundances showed that the PF treatment may influence different metabolic pathways compared to CHS, while AHS shared some similarities with CHS. Understanding both the direct effects of CHS and indirect effects through depressed FI, along with the short-term effects from AHS, will be of importance in devising nutritional strategies to maintain gut microbial balance and limit negative effects to broiler chickens’ performance and health.