Strongyle nematode fauna in three ruminants in upper northern Thailand.

Gastrointestinal parasites, particularly strongyle nematodes, pose a significant threat to the health of ruminants. Due to the technical limitations of microscopic and conventional PCR-based methods, the strongyle parasite fauna has not been well studied even in common livestock animals. The present study aimed to investigate the prevalence and diversity of strongyle nematodes in three ruminant species in northern Thailand using a nemabiome approach. Fecal samples were collected from buffaloes, cattle, and goats that were raised for meat and for dairy in four provinces in northern Thailand. Strongyle infections were determined using egg flotation and McMaster techniques followed by DNA metabarcoding for species identification. The results showed high prevalence of strongyles especially in goats raised for meat (88 %), and in goats raised for dairy (72 %). Significantly more goats and cattle raised for meat were strongyle egg-positive compared to their dairy counterparts. Notably, deworming frequency was not significantly associated with strongyle egg-positivity in all ruminant groups apart from dairy goats. Nemabiome analysis identified 11 strongyle species across seven genera. Among the ruminant hosts, beef cattle exhibited the highest strongyle richness. Additionally, the dominance of specific strongyle species influenced the differences observed in diversity indices. This research is the first to apply the nemabiome approach to assess strongyle nematode diversity in northern Thailand, providing valuable insights into nematode community compositions. These findings emphasize the importance of molecular techniques for parasite monitoring and the development of targeted control strategies.