Heat Stress and Gut Microbiome Dynamics in Poultry: Interplay, Consequences, and Mitigation Strategies

Poultry production is severely hampered by rising global temperatures, especially in tropical and subtropical areas. The gut microbiome, a complex and dynamic microbial ecosystem essential for digestion, immunity, and overall health, is significantly impacted by heat stress. The microbial equilibrium is altered during heat stress, disrupting intestinal integrity, limiting nutrient absorption, and increasing susceptibility to diseases. This review highlights the physiological, immunological, and microbiological effects of prolonged heat exposure while examining the complex interactions between heat stress and gut microbiome dynamics in poultry. Recent research studies suggest that heat stress contributes to gut dysbiosis, characterized by an increase in opportunistic pathogens, a decline in beneficial bacteria (such as Lactobacillus spp.), and a decrease in microbial diversity. These alterations are frequently accompanied by oxidative stress, systemic inflammation, increased intestinal permeability, and compromised tight junction integrity. Various mitigating techniques have been explored to enhance poultry resilience to heat stress and to promote gut health, including the nutritional (such as probiotics, prebiotics, phytogenics, functional amino acids, and insect-based feed additives) and non-nutritional (such as genetic selection, habitat modifications, and thermal conditioning) interventions, which are critically evaluated in this review. Additionally, mechanistic insights into how these interventions promote immune regulation, host-microbiome interactions, and epithelial barrier function are also discussed. By integrating environmental, nutritional, and microbiological perspectives, this analysis identifies promising strategies to enhance poultry gut health, welfare and productivity in today's era of climate change. Proposed avenues for further research include context-specific solutions for heat-stressed poultry and omics-driven investigations.