Effect of the dietary supplementation with sodium butyrate on gut morphology and caecal microbiota of broiler chickens

A total of 900 chicks (Ross 308) were housed in 36 pens (25 animals/pen) according to a 3 × 2 × 2 factorial design encompassing three dietary supplementation rates of microencapsulated sodium butyrate (0 mg/kg, 150 mg/kg, and 300 mg/kg), two levels of ether extract (grower diet 6.7% vs. 7.7%; finisher diet 7.7% vs. 8.9%), and two sexes (males vs. females). The grower and finisher diets were based on maize (56-62%), soybean meal (25-31%), and full fat soybean (5.5-9.0%), besides animal fat (2.5-5.0%). Health and growth performance were monitored from hatching until commercial slaughtering at 42 d of age. At 39 d of age, 36 chickens (1 per pen, 6 per experimental diet) were slaughtered and jejunum tissue and caecal content sampled. The jejunum was stained with hematoxylin/eosin for morphometric evaluation. The intestinal microbiota was evaluated by sequencing of V2, V4, V8 and V3, V6-V7, V9 regions of the rRNA 16S gene. The dietary supplementation with sodium butyrate did not affect growth performance: final live weight averaged 2,733 g, with an average feed intake of 182 g/d and a feed conversion ratio of 1.53. Similarly, nor the dietary supplementation with sodium butyrate nor the fat level affected gut morphology or microbiota composition at 39 d of age. As for sex, performance was higher in males compared to females. The latter also showed greater ratio villi/crypt compared to males (4.63 vs. 4.12; P=0.02) without differences in villi length or crypt depth. Both alpha and beta diversity significantly changed between the bacterial community of females and males. Regardless from the dietary treatment and sex, at a phylum level, Firmicutes was the most represented and Bacteroidetes was the least; at a genus level, Faecalibacterium dominated, followed by an Uncultured genus of the Lachnospiraceae family, Parabacteroides, Lactobacillus, and Bacteroides. In conclusion, under the good health conditions of the present trial (mortality <1%), the different dietary treatments, with regard to sodium butyrate supplementation and fat content, did not affect gut health and microbiota of broiler chickens.