Gastrointestinal parasites of a reintroduced semi-wild Plains bison (Bison bison bison) herd: Examining effects of demographic variation, deworming treatments, and management strategy

Authors: WIESE, JOSHUA - The Crane Trust, Inc; CAVEN, ANDREW - The Crane Trust, Inc; Zarlenga, Dante; TOPLIFF, CHRISTINA - The Crane Trust, Inc

Submitted to: International Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2021
Publication Date: 2/17/2021
Citation: Wiese, J.D., Caven, A.J., Zarlenga, D.S., Topliff, C.L. 2021. Gastrointestinal parasites of a reintroduced semi-wild Plains bison (Bison bison bison) herd: Examining effects of demographic variation, deworming treatments, and management strategy. International Journal of Parasitology. 14:216-227. https://doi.org/10.1016/j.ijppaw.2021.02.004.
DOI: https://doi.org/10.1016/j.ijppaw.2021.02.004

Interpretive Summary: Bison are exposed to parasites that are similar to cattle. Like cattle, production losses, clinical disease, and mortality due to parasitism have led to deworming as a common practice for bison where data suggests that bison are infected at higher rates. Recommended best practices for bison management include diagnosis of gastrointestinal parasite infection levels and efficiency testing of anthelmintic treatments. However, questions remain over the effectiveness and need for drug treatment in conservation-oriented, semi-wild herds. Better information on geographical distribution and diversity of GI nematodes in bison is needed, especially in understudied landscapes. Herein we examined 1) temporal and demographic variation in bison GI nematode FECs in response to land use history and land management practices; 2) the identification of prominent infecting parasite species; and 3) the effectiveness of moxidectin and fenbendazole drug treatments over time. These data provide more complete information on regional distribution, effectiveness of management regimes, and the development of natural immunity to GI nematodes. The information will aid in generating new practices for producers and scientists and provide guiding principles on best practices for production and treatment in semi-wild and conservation herds alike.

Technical Abstract: Plains bison (Bison bison bison) are being reintroduced into semi-wild, spatially constrained herds across North America. Herd managers are concerned about gastrointestinal (GI) nematode parasites as they attempt to care for the clinical health of their bison. We examine how demographics, grazing location, herd management, and anthelmintic treatments affect the levels of GI nematode infections within a recently reintroduced bison herd in the Great Plains. We also examine which strongylid-type parasites are shared between cattle and bison in this locality. Our results suggest that younger bison (<2 years of age) experience higher numbers of GI nematodes and that some taxa are more prevalent throughout different periods of a bison’s early years. Demographic findings suggest that calf and yearling (0-2 yrs. age) bison have the highest FECs and that these decline until reaching a low in peak adulthood and thereafter (x > 6 yrs. of age). Both Trichuris spp. and particularly Nematodirus spp. were much more abundant, relatively, during the first year of a bison’s life. This pattern was also true of Moniezia spp. and Eimeria spp., however, strongyle-type spp. appeared to peak in relative abundance during the second year of life. Our data also indicate that parasite counts are influenced by differences in land-use histories of pastures previously grazed by cattle or by the proportion of frequent flooding in different pastures. Our comparative treatment results suggest that fenbendazole is more effective than moxidectin at treating GI nematodes in bison. Multiplex PCR assays revealed the presence Ostertagia spp., Haemonchus placei, Cooperia onchophora, and strongyle-type spp. in both metapopulations. Only one metapopulation tested positive for Oesophagostomum spp, while neither metapopulation tested positive for Trichostrongylus columbriformis.