Effects of dietary sodium bicarbonate on bacterial diversity of intestinal microbiota in laying hens

The aim of this study was to investigate the effect of dietary supplement with sodium bicarbonate(NaHCO3)on moisture content and pH value in feces,and microbial flora from cecum,and to identify the tolerated dose range of NaHCO3in the diets of laying hens.Nine hundred 21-weeks-old Hy-Line brown laying hens were randomly assigned to 5groups with 6replicates of 30birds each.Laying hens were fed a basal diet with 0,and 0.1%,0.5%,2.5%and 5% NaHCO3for10weeks,respectively.The results showed as follow:compared with control,the number of Lac tobacilliin 0.1% NaHCO3group was increased,the number of E.coli was decreased,and the index of caecum bacterial diversity was also higher(P0.05).In 0.5% NaHCO3group,the pH value in feces was little higher than that of control group(P0.05),and the number of Lactobacilli and the index of caecum bacterial diversity were increased(P0.05),respectively.In addition,the pH value and moisture content in feces from 2.5%and 5% group were significantly increased compared with other groups(P0.01).However,in 2.5%and 5% NaHCO3groups,the number of Lactobacilli was decreased(P0.05or P0.05),but the number of E.coli was increased(P0.05or P0.05),respectively.Moreover,the index of caecum bacterial diversity in 5% group was lower than that of control,0.1% and 0.5% group(P0.05),respectively.It is concluded that excessive supplementation of NaHCO3(2.5%)in dietary of laying hens causes serious diarrhea,and disorder of enterobacteria balance in caecum.However,the supplementation of NaHCO3 at0.5%level can facilitate the growth of beneficial bacterium and bacterial diversity in intestine,and maintain the laying performance.Therefore,this study suggests that the tolerated dose of NaHCO3 in diet of laying hens is 0.5%.