Biological response of heat-stressed chickens to dietary supplementation with Chlorella vulgaris: an RNA-seq analysis

In modern poultry production, heat stress represents one of the primary management and health challenges, impairing growth performance, feed conversion efficiency, and meat quality in broiler chickens. In this context, nutrigenomics provides innovative tools to understand how targeted dietary interventions may modulate molecular stress response mechanisms. Therefore, this study aims to evaluate the mitigating potential of microalgae (Chlorella vulgaris) by analysing the biological response of Ross 308 broiler chickens exposed to chronic heat stress. Three experimental groups were evaluated: chickens under thermoneutral conditions fed a control diet (TN-C0), chickens under heat stress fed a control diet (HS-C0), and chickens under heat stress fed a diet supplemented with 6% C. vulgaris (HS-C6), with male and female birds analysed separately. Transcriptomic analysis (RNA-seq) of jejunal tissue revealed distinct sex-specific transcriptional responses. In females, C. vulgaris supplementation induced a regulatory pattern opposing that triggered by heat stress, particularly among genes involved in lipid transport, fatty acid metabolism, and extracellular matrix organization, suggesting a potential mitigating effect of the microalga on heat-stress-related-pathways. Notably, although male chickens exhibited a substantially lower number of differentially expressed genes (DEGs) compared to females, they demonstrated a similar inverse transcriptional response, showing reversed expression patterns following dietary inclusion. Overall, dietary supplementation with C. vulgaris modulates the intestinal transcriptional response to chronic heat stress, suggesting a potential protective role of C. vulgaris at the intestinal level in broiler chickens.