Effect of <i>Bacillus hisashii</i> Supplementation on the Growth Performance, Nitrogen Excretion, and Intestinal Microbiota of Broiler Chickens Fed Low Crude Protein Diet

The present study evaluated the effects of feeding a newly found thermophile, Bacillus hisashii, on broiler chickens fed a low crude protein (CP) diet. One hundred day-old male Ross 308 broiler chicks are randomly assigned to four treatment groups of five replicates (five birds per replicate). The groups were fed the isocalorically formulated diets containing normal CP (NCP) or low CP (LCP; -2.0% pt) and the diets supplemented with the B. hisashii probiotics (Pro) until 42 days of age. The LCP diet significantly reduced body weight at 42 days, and the probiotics partially suppressed the reduction. There was no difference in feed intake between the groups, and Pro significantly lowered the feed conversion ratio and fecal nitrogen content in the LCP diet (p < 0.05). The probiotics significantly decreased mucosal interleukin-6 concentration in the LCP diet. There were no differences in α-diversity indices of the cecal microbial community, while Pro improved the relative abundance of the genera Lactobacillus and Escherichia-Shigella in the LCP diet. There were significant differences in β-diversity between the groups, excluding NCP/Pro versus LCP. The results suggest that B. hisashii supplementation improved growth performance and intestinal inflammatory status, possibly through improving intestinal microbial composition and balance in broiler chickens.