16S rDNA-based detection technology: use in lambs infected with <i>Nematodirus oiratianus</i> to analyze changes in intestinal flora

The nematode Nematodirus oiratianus is associated with major economic losses in the livestock industry, as it is a common gastrointestinal parasites of cattle, sheep, and other ruminants. These parasites primarily obtain nutrients by consuming the blood of their host. This study aimed to investigate changes in the intestinal microbiota of lambs infected with N. oiratianus before and after infection, using 16S rDNA sequencing technology. We aimed to reveal the impact of N. oiratianus infection on lamb intestinal microecology and to provide scientific evidence for the prevention and control of related diseases. Compared with the infected group, the control group had more bacterial species. Chao, Ace, and Shannon indices were significantly lower in the infected group (p < 0.05), while the Simpson index showed no significant difference (p > 0.05). These findings collectively indicate significant divergence in the composition of bacterial taxa between the infected and control groups. The phylum with the highest relative abundance in both groups was Firmicutes, followed by Bacteroidetes. Linear Discriminant Analysis Effect Size (LEfSe) identified significantly enriched taxa, including Proteobacteria, Bacteroides, and Campylobacteria in the control group, and Clostridiales, Firmicutes, and Ruminococcaceae in the infected group. Functional predictions indicated that the altered microbiota was associated with metabolic pathways such as carbohydrate, amino acid, and vitamin metabolism. Infection with N. oiratianus led to significant alterations in the diversity and composition of the intestinal microbiota in lambs.