本试验旨在研究饲粮中添加不同水平的叶酸和维生素B₁₂对雏鹅盲肠菌群结构的影响。选取1日龄健康五龙鹅360只，随机分成6个组，每组6个重复，每个重复10只鹅（公母各占1/2）。试验采用2×3（叶酸×维生素B₁₂）两因素交叉等重复的析因设计，饲粮中叶酸的添加水平分别为0.55、2.50 mg/kg，维生素B₁₂的添加水平分别为0.009、0.018、0.036 mg/kg。Ⅰ~Ⅵ组饲粮中叶酸和维生素B₁₂添加水平分别为0.55和0.009 mg/kg、2.50和0.018 mg/kg、0.55和0.036 mg/kg、2.50和0.009 mg/kg、0.55和0.018 mg/kg、2.50和0.036 mg/kg。试验期为4周。试验结束后，采用16S rRNA高通量测序技术对雏鹅盲肠菌群组成进行测定，基于Illumina HiSeq测序平台，利用双末端测序的方法，构建小片段文库进行测序，并进行α多样性和差异显著物种分析。结果显示：1）饲粮中添加不同水平的叶酸和维生素B₁₂对雏鹅的终末体重、平均日增重有显著影响（P<0.05），对料重比无显著影响（P>0.05）。Ⅳ组的终末体重和平均日增重显著高于其他5组（P<0.05）。2）Ⅳ组的操作分类单元（OUT）数、ACE指数、Chao1指数最高，说明盲肠微生物的物种丰度高于其他5组。聚类分析表明Ⅰ组与Ⅵ组盲肠菌群相似性最高，Ⅰ组与Ⅱ组盲肠菌群相似性最低。3）雏鹅盲肠中厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidetes）和变形菌门（Proteobacteria）为优势菌门，饲粮添加不同水平的叶酸和维生素B₁₂使雏鹅盲肠菌群门水平丰度发生了变化，其中厚壁菌门、拟杆菌门和变形菌门变化明显。雏鹅盲肠样本中共检测到91个菌属，Ⅰ~Ⅵ组分别检测到86、84、83、87、87、83个菌属，相对丰度较高的5个属分别为脱磷弧菌属（Desulfovibrio）、杆菌属（Bacterium）、拟杆菌属（Bacteroides）、另枝菌属（Alistipes）和巴那斯拉菌属（Barnesiella）。优势菌属的相对丰度在不同组之间存在较大差异。在种水平上，杆菌在各组盲肠菌群中均占有绝对优势，其相对丰度在Ⅰ~Ⅵ组分别为93.5%、93.7%、87.8%、95.2%、93.4%和87.9%，组间差异不显著（P>0.05）。由此得出，饲粮中添加2.50 mg/kg叶酸和0.009 mg/kg维生素B₁₂能够优化雏鹅盲肠菌群结构，增加有益菌的丰度，进而提高生长性能。

This study investigated the effects of different folic acid and vitamin B₁₂ supplemental levels in diets on the caecal microflora structure of gosling. A total of 360 one-day-old Wulong geese were randomly divided into 6 groups, each group had 6 replicates and each replicate consisted of 5-male and 5-female geese. A 2×3 two-factor (folic acid×vitamin B₁₂) crossed equal replication factorial design was used in this experiment, the folic acid supplemental levels in diets were 0.55 and 2.50 mg/kg, respectively, and the vitamin B₁₂ supplemental levels in diets were 0.009, 0.018 and 0.036 mg/kg, respectively. The folic acid and vitamin B₁₂ supplemental levels in diets of groups Ⅰ to Ⅵ were 0.55 and 0.009 mg/kg, 2.50 and 0.018 mg/kg, 0.55 and 0.036 mg/kg, 2.50 and 0.009 mg/kg, 0.55 and 0.018 mg/kg, 2.50 and 0.036 mg/kg, respectively.The experiment lasted for 4 weeks. The 16S rRNA high throughput sequencing technology was used to investigate the microbial diversity in the caecum of gosling after the feeding experiment. Based on the Illumina HiSeq sequencing platform, a small fragment library was constructed by paired-end sequencing, and then carried on α diversity and significantly different species analysis. The results showed as follows:1) dietary supplemented different levels of folic acid and vitamin B₁₂ had significant effects on final body weight (FBW) and average body weight (ADG) of gosling (P<0.05), but had no significant effect on feed/gain (F/G) (P>0.05). The FBW and ADG in group Ⅳ were significantly higher than those in the other 5 groups (P<0.05). 2) The operational taxonomic unit (OUT) number, ACE index and Chao1 index of group Ⅳ were the highest, which demonstrated that the species abundance of group Ⅳ was higher than that of the other 5 groups. Clustering analysis showed that the caecal microflora of groups Ⅰ and Ⅵ had the highest similarity, and that of groups Ⅰ and Ⅱ had the lowest similarity. 3) Firmicutes, Bacteroidestes and Proteobacteria were the predominant bacteria phylums. Caecal abundance microflora in phylum level was changed by dietary supplemented different levels of folic acid and vitamin B₁₂, and the Firmicutes, Bacteroidestes and Proteobacteria changed obviously. A total of 91 different genera were detected in the ceacal samples. From groups Ⅰ to Ⅵ, 86, 84, 83, 87, 87 and 83 genera were detected, respectively. The higher relative abundant genera were Desulfovibrio, Bacterium, Bacteroides, Alistipes and Barnesiella. The abundance of dominant genera existed major difference among different groups. In species level, Bacilus had an absolute advantage in the caecal microflora of each group, the relative abundance of Bacillus in groups Ⅰ to Ⅵ was 93.5%, 93.7%, 87.8%, 95.2%, 93.4% and 87.9%, respectively, and no significant difference was found among groups (P>0.05). It is concluded that adding 2.5 mg/kg folic acid and 0.009 mg/kg vitamin B₁₂ into the diet can optimize the caecal microflora structure, and increase the abundance of beneficial microorganisms, thus to improve the performance of gosling.