Compound Probiotics Alleviate Gut Microbiota Dysbiosis Induced by Heat Stress in Broilers

Heat stress represents a key environmental challenge in poultry production, markedly impairing broiler health and productivity. This study investigated the association between compound probiotic supplementation and the gut microbial community structure in heat-challenged broilers, analyzing the cecal contents from both groups using 16S rDNA amplicon sequencing. Compound probiotic supplementation was associated with changes in alpha diversity and richness of the cecal microbiota, with lower Shannon, Chao1, and ACE indices (p < 0.05). At the phylum level, compound probiotic supplementation significantly increased the relative abundance of Bacteroidota (p < 0.001) while decreasing that of Proteobacteria (p < 0.0001) in the cecum of broilers, whereas the relative abundances of Firmicutes and Verrucomicrobiota showed increasing trends. At the genus level, the relative abundance of Bacteroides (p < 0.0001) was significantly increased in the HP group, whereas Lactobacillus and Fusobacterium exhibited decreasing trends compared with the HS group. LEfSe analysis suggested Verrucomicrobia as a potentially enriched taxon in the HP group. Furthermore, KEGG level 3 functional prediction suggested enrichment of predicted pathways related to starch and sucrose metabolism, as well as amino acid and nucleotide metabolism in the HP group. These findings suggest that compound probiotics are associated with changes in gut microbial composition and predicted functions in heat-stressed broilers, providing preliminary, exploratory insights into their potential associations under heat stress.