日粮添加碳酸氢钠对蛋鸡肠道菌群多样性的影响

900羽21周龄海兰褐蛋鸡随机分成5组，每组6个重复，每个重复30羽。分别在基础日粮中添加0、0．1％、0．5％、2．5％、5％NaHCO3，持续10周。结果显示，与对照组相比，0．1％组蛋鸡盲肠乳酸菌数量增加，大肠杆菌数量降低，菌群多样性指数提高（P〉0．05）。0．5％组蛋鸡粪便pH值显著提高（P〈0．05），乳酸菌数量增加，菌群多样性指数提高（P〉0．05）。2．5％、5％组蛋鸡粪便pH值、水分含量极显著高于其他组（P〈0．01）。同时，2．5％、5％组盲肠乳酸杆菌数量降低（P〉0．05或P〈0.05），大肠杆菌数量增高（P〉0．05或P〈0．05），5％组菌群多样性指数亦显著降低前3组（P〈0．05）。结果表明，日粮添加NaHCO3超过2．5％，蛋鸡腹泻严重，肠道菌群平衡严重破坏。而当NaHCO3的添加量低于0．5％时，肠道有益菌数量和菌群多样性指数呈增加趋势，蛋鸡生产性能维持正常。因此，本试验提示蛋鸡生产中饲料添加剂NaHCO3最高耐受量为0．5％。

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 （NaHCOa） on moisture content and pH value in feces,and microbial flora from cecum, and to identify the tolerated dose range of NaHCO3 in the diets of laying hens. Nine hundred 21- weeks-old Hy-Line brown laying hens were randomly assigned to 5 groups with 6 replicates of 30 birds each. Laying hens were fed a basal diet with 0,and 0.1%,0.5%,2.5% and 5% NaHCO3 for 10 weeks,respectively. The results showed as follow.compared with control, the number of Lactobacilli in 0.1% NaHCO3 group was increased,the number of E. coli was decreased, and the index of caecum bacterial diversity was also higher （P〈0.05）. In 0.5% NaHCO3 group,the pH value in feces was little higher than that of control group （P%0.05） ,and the number of Lactoba-cilli and the index of caecum bacterial diversity were increased （P〉0.05）, respectively. In addition,the pH value and moisture content in feces from 2.5% and 5% group were significantly increased compared with other groups （P〈0.01）. However,in 2.5% and 5% NaHCO3 groups,the number of Lactobacilli was decreased （P〉0.05 or P〈0.05）,but the number of E. coli was increased （P〉0.05 or P〈0.05）, respectively. Moreover, the index of caecum bacterial diversity in 5% group was lower than that of control,0.1% and 0.5% group （P〈0.05）,respectively. It is concluded that excessive supplementation of NaHCOs （〈2.5%） in dietary of laying hens causes serious diarrhea,and disorder of enterobacteria balance in caecum. However, the supplementation of NaHCOa at %0.5 〈 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 NaHCOa in diet of laying hens is 0.5 %.