High levels of third-stage larvae (L3) overwinter survival for multiple cattle gastrointestinal nematode species on western Canadian pastures as revealed by ITS2 rDNA metabarcoding

Abstract

Background The ability of infective larvae of cattle gastrointestinal nematode (GIN) species to overwinter on pastures in northerly climatic zones with very cold dry winters is poorly understood. This is an important knowledge gap with critical implications for parasite risk assessment and control. Methods Infective third-stage larvae (L3) were quantified in samples of fecal pats, together with adjacent grass and soil, before and after winter on three farms in southern, central and northern Alberta. Nemabiome ITS2 metabarcoding was then performed on the harvested L3 populations to determine the species composition. Finally, parasite-free tracer calves were used to investigate if the L3 surviving the winter could infect calves and develop to adult worms in spring. Results Farm level monitoring, using solar powered weather stations, revealed that ground temperatures were consistently higher, and less variable, than the air temperatures; minimum winter air and ground temperatures were − 32.5 °C and − 24.7 °C respectively. In spite of the extremely low minimum temperatures reached, L3 were recovered from fecal pats and grass before and after winter with only a 38% and 61% overall reduction over the winter, respectively. Nemabiome ITS2 metabarcoding assay revealed that the proportion of L3 surviving the winter was high for both Cooperia oncophora and Ostertagia ostertagi although survival of the former species was statistically significantly higher than the latter. Nematodirus helvetinaus and Trichostrongylus axei could be detected after winter whereas Haemonchus placei L3 could not overwinter at all. Adult C. oncophora, O. ostertagi and N. helvetianus could be recovered from tracer calves grazing after the winter. Conclusions The largest proportion of L3 were recovered from fecal pats suggesting this is important refuge for L3 survival. Results also show that L3 of several GIN parasite species can survive relatively efficiently on pastures even in the extreme winter conditions in western Canada. Tracer calf experiments confirmed that overwintered L3 of both C. oncophora and O. ostertagi were capable of establishing a patent infection in the following spring. These results have important implications for the epidemiology, risk of production impact and the design of effective control strategies. The work also illustrates the value of applying ITS2 nemabiome metabarcoding to environmental samples.

Risk factors and hematological profile associated with colic in Delman horses in Gresik, Indonesia

“…Humid conditions support infective larvae to survive. 27 There were 21 cases of colic horse with dental disease in our sample (Table 2). Special treatment is needed due to the condition of the horses' teeth, which are not suitable for chewing hard grass.…”

Seasonal epidemiology of gastrointestinal nematodes of cattle in the northern continental climate zone of western Canada as revealed by internal transcribed spacer-2 ribosomal DNA nemabiome barcoding

“…The recovery rates of the grass and fecal L3 protocols were 22.0% and 14.4%, respectively, and were applied to the calculation of available L3. Grass samples were processed following a flotation and sieving protocol, as described by Wang et al [ 13 ]. The total number of L3 that migrated from one fecal pat onto grass ( L3 g) was calculated as follows: where L3 s is the number of L3 in each sampling unit.…”

“…These locations differ from more temperate regions in several important ways, including the occurrence of extremely cold and dry winters and drier summers with sporadic but sometimes heavy precipitation [ 16 ]. Recent work has shown that L3 of both Ostertagia ostertagi and Cooperia oncophora can survive over the winter in significant numbers on pastures in western Canada, despite the very low temperatures and low humidity at this time of the year, with the fecal pat being an important refuge [ 13 ]. Fecal egg counts are known to increase over the summer grazing season in beef cattle in western Canada, and there is some evidence that temperature and accumulated precipitation are significant predictors of O. ostertagi serum antibody concentrations [ 17 , 18 ].…”

“…Co-infections of multiple GIN species are common in cattle worldwide, with species composition varying between regions [ 20 , 21 ]. Cooperia oncophora and O. ostertagi are the two most prevalent GIN species in western Canada [ 8 , 13 ]. Ostertagia ostertagi is the most pathogenic species in cattle, and although it can show anthelmintic resistance, reports of this are not common for North American beef cattle [ 22 , 23 ].…”

“…Given the differences in the pathogenicity, epidemiology and drug sensitivity that exist among GIN species, species-specific information is important both for routine diagnostics and epidemiological studies. Nemabiome metabarcoding is a recently developed approach used to determine the relative proportions of strongylid species in fecal or pasture larval samples, and is well suited to epidemiological or surveillance studies involving large numbers of samples [ 8 , 13 , 21 ].…”