Effect of supplementation of nicotinamide and sodium butyrate on the growth performance, liver mitochondrial function and gut microbiota of broilers at high stocking density.

This study was conducted to investigate the effects of stocking density and dietary nicotinamide (NAM) and butyrate sodium (BA) supplementation on the growth performance, liver mitochondrial function and gut microbiota of broilers at high stocking density. A total of 342, 26-d-old Cobb500 broilers were divided into 5 groups with 6 replicates. Treatments were as follows: (a) Low stocking density (L, 9 birds per cage); (b) High stocking density (H, 12 birds per cage); (c) H + 50 ppm NAM; (d) H + 500 ppm BA; (e) H + 50 ppm NAM + 500 ppm BA (COMB). The results showed that high stocking density significantly reduced the feed intake and body weight gain of broilers, while COMB improved the growth performance at high stocking density. High stocking density significantly reduced the liver metallothionein content, liver mitochondrial membrane potential and the activities of Na+K+-ATPase and Ca2+Mg2+-ATPase. In contrast, the liver metallothionein contents in the NAM, BA and COMB fed group were higher than those in the H group. COMB increased the activity of ATPase as well, but it failed to enhance the mitochondrial membrane potential. Stocking density also affected gut microbiota of broilers. The high-density group increased the relative abundance of Blautia. Supplementation of BA and NAM increased the abundance of Lactobacillus and Bifidobacteria, respectively. In conclusion, a combination of NAM and BA can improve the performance, antioxidant capacity, mitochondrial function and intestinal microbiota of broilers at high stocking density.