目的 明确宁夏银川地区奶牛毕氏肠微孢子虫的感染情况及其主要基因型。 方法 2021年8月—2022年8月，在银川市及周边县6个规模化奶牛场采集奶牛新鲜粪样（包括腹泻粪样和非腹泻粪样），提取粪样基因组DNA，用毕氏肠微孢子虫内部转录间隔区（ITS）引物进行巢式PCR，回收PCR产物后送测序并进行BLAST比对，鉴定毕氏肠微孢子虫基因型。采用SPSS 25.0软件进行分析，不同月龄奶牛毕氏肠微孢子虫阳性率差异的比较采用χ²检验。 结果 共采集奶牛粪样772份，巢式PCR扩增结果显示，奶牛毕氏肠微孢子虫阳性率为8.7％（67/772），目的条带大小约为400 bp。不同牧场的奶牛毕氏肠微孢子虫阳性率为4.8%（6/124）~11.5%（18/156），差异有统计学意义（χ² = 30.828，P < 0.05）。5~7月龄犊牛的阳性率最高（15.6%，23/147），12月龄以上育成牛的最低（3.4%，5/149），不同月龄的奶牛阳性率差异有统计学意义（χ² = 59.529，P < 0.05）。腹泻粪样中毕氏肠微孢子虫的阳性率为10.6%（42/398），高于非腹泻粪样（6.7%，25/374）（χ² = 3.419，P < 0.05）。测序共检出66条毕氏肠微孢子虫序列，分为CHN4、BEB4、J、I型等4种基因型，提交GenBank获得的登录号分别为OR352930、OR352929、OR352932和OR352931。其中CHN4型3条（占4.5%），与G1亚群CHN4基因型（HM992511）的序列一致性为98.4%；BEB4型18条（占27.3%），与G2亚群BEB4基因型（AY331008）的序列一致性为96.3%；J型22条（占33.3%），与G2亚群J基因型（AF135837）的序列一致性为93.1%；I型23条（占34.9%），与G2亚群I基因型（AF135836）的序列一致性为91.1%。不同月龄奶牛感染的毕氏肠微孢子虫的优势基因型不同，BEB4型、J型和I型毕氏肠微孢子虫在奶牛的各个月龄段均存在，3种基因型的总和分别占阳性腹泻粪样和阳性非腹泻粪样的88.1%（37/42）和60.0%（15/25），二者差异有统计学意义（χ² = 3.419，P < 0.05）。 结论 宁夏银川地区奶牛存在毕氏肠微孢子虫感染，主要基因型为BEB4、J和I基因型。

Objective To clarify the prevalence and main genotypes of Enterocytozoon bieneusi infection in dairy cows in Yinchuan area of Ningxia Province. Methods From August 2021 to August 2022, cow fresh fecal samples (including diarrheal and non-diarrheal samples) were collected from 6 scaled dairy farms in Yinchuan City and the surrounding counties. The genomic DNA was extracted from the fecal samples, and nested PCR was performed using E. bieneusi internal transcriptional spacer (ITS) primers. The PCR amplicaons were seqeuced, and sequence alignment was conducted using BLAST to identify the genotype of E. bieneusi. SPSS 25.0 software was used for statistical analysis, and χ² test for comparing the differences in positive rates between the cows of different months of age. Results A total of 772 fresh cow fecal samples were collected. The E. bieneusi positive rate from nested PCR amplification was 8.7% (67/772). The target band size was approximately 400 bp. The E. bieneusi positive rate found in different farms ranged from 4.8% (6/124) to 11.5% (18/156), with statistically significant differences (χ² = 30.828, P < 0.05). The highest positive rate was found in cows aged 5-7 months (15.6%, 23/147) and the lowest was found in cows aged above 12 months (3.4%, 5/149). There was a statistically significant difference in the positive rate of E. bieneusi among cows of different months of age (χ² = 59.529, P < 0.05). The E. bieneusi positive rate in diarrheal samples was 10.6% (42/398), which was higher than that in non-diarrheal samples (6.7%, 25/374) (χ² = 3.419, P < 0.05). The 66 E. bieneusi sequences could be classified into 4 genotypes, including CHN4, BEB4, J and I. The accession obtained by GenBank were OR352930, OR352929, OR352932 and OR352931 respectively. 3 sequences were CHN4 (account for 4.5%), which showed a 98.4% identity to the sequence of CHN4 (HM992511) in G1. 18 sequences were BEB4 (account for 27.3%), which showed a 96.3% identity to the sequence of BEB4 (AY331008) in G2. 22 sequences were J (account for 33.3%), which showed a 93.1% identity to the sequence of J (AF135837) in G2. 23 sequences were I (account for 34.9%), which showed a 91.1% identity to the sequence of I (AF135836) in G2. The dominant E. bieneusi genotypes in cows varied with age, but BEB4, J and I presented in all age groups. The BEB4, J and I accounted for 88.1% (37/42) and 60.0% (15/25) of the total positive diarrheal samples and positive normal samples respectively, with statistically significant differences (χ² = 3.419, P < 0.05). Conclusion E. bieneusi infection was found in dariy cows in Yinchuan area of Ningxia Province, with the main genotypes BEB4, J and I.