The dynamics of gastrointestinal nematodes present in co-grazed host species kept in a Scottish zoological collection.

This research aims to understand the diversity of gastrointestinal infections in different grazing animals kept together in a Scottish zoo. The study uses modern genetic techniques to identify the various nematode species present and examines their dynamics across different host animals.

Research Methodology

• The researchers collected faecal samples from horses, sheep, goats, alpacas, and deer grazing together in a Scottish zoological collection. A single time-point study was performed, meaning that the samples were collected at a specific instance rather than over a period of time.
• To count the number of nematode eggs in the faeces, a saturated saline centrifugal flotation cuvette technique was used, producing the Faecal Worm Egg Counts (FWECs).
• To identify the specific species of nematodes present in the faecal samples, deep-amplicon sequencing of two markers (ITS-2 and mitochondrial ND-4) was performed. This method allows for a detailed analysis of genetic material, helping to understand the infection dynamics between different host species.

Research Findings

• The FWECs varied greatly across the different species. Alpacas had the lowest count (7 eggs per gram of faeces) while goats had the highest (461 eggs per gram).
• The genetic sequencing identified nine different GIN species and some unclassified groups. The most common species were Haemonchus contortus, found primarily in alpacas and sheep, and Cylicocyclus longibursatus, common in horses.
• A great genetic diversity was found in H. contortus across different hosts. Alpacas and sheep showed the highest number of sequence variants.
• Based on the analysis of the mitochondrial ND-4 gene, the researchers theorize that there may be evolutionary pressures shaping these nematode infections. Balancing selection was particularly noticeable in alpacas and sheep.
• Several unclassified sequences were identified, predominantly in deer.

Conclusions of the Study

• This study showcases the intricate dynamics of gastrointestinal nematode infections within mixed-species grazing systems. It highlights the complexity of infection dynamics within different host species and the genetic diversity of the nematodes.
• The use of new genomic technologies combined with traditional faecal parasitology proves successful at elucidating these complex relationships.
• The findings could lead to the development of more comprehensive management strategies for GIN infections in zoological collections, as well as in other mixed-species grazing setups.