Dietary supplementation with sodium butyrate: gut response at different ages and microbiota composition of female and male broiler chickens

This study investigated the effects of two Na-butyrate supplementations (150 and 300 mg/kg) and dietary fat contents (HF diet: 8.9% ether extract vs. LF diet:7.7% ether extract) on 900 Ross 308 male and female broiler chickens' gut morphology, immune response, and caecal microbiota composition. Gut morphology and immune-histochemistry analyses were performed on jejunum tissues sampled at 14, 28, and 42 days. Additionally, 16S rRNA gene multi-amplicon sequencing was used to assess caecal microbiota composition at 42 days. Results indicated no significant effects of Na-butyrate, dietary fat or animal sex on villi height, crypt depth, or CD45+ cell density. However, villi height and crypt depth increased with age, while the villi/crypt ratio varied. Microbiota analysis revealed Firmicutes as the dominant phylum, with sex-related differences observed in microbial diversity indices (Simpson index, p =.02). Na-butyrate supplementation and dietary fat affected the abundance of specific bacterial taxa, notably within male chickens. However, no significant functional changes in microbial communities were detected. These findings suggest that while under the good health conditions of the present trial, Na-butyrate and dietary fat levels do not significantly alter gut morphology or immune cell density, they can influence the composition of the caecal microbiota.