Population study of bovine Ostertagia spp infective larvae on herbage and in soil

Observations on the bionomics of the free-living stages of Trichostrongylus vitrinus

“…Some larvae do migrate into the soil as evidenced by occasional sampling of the soil of plots. Recent work with Ostertagia ostertagi (see BAIRDEN et al, 1979;AL SAQUR et al, 1982) has implicated the soil as a reservoir for considerable numbers of infective larvae which overwinter there to migrate back on to the herbage in the late summer. The results of this work are important in relation to control measures involving moving stock on to what is considered to be clean pasture, so it is essential to know how widespread this phenomenon is inrelation to the nematode parasites of farm animals on pasture.…”

The distribution of the infective larvae of sheep gastro-intestinal nematodes in soil and on herbage and the vertical migration of Trichostrongylus vitrinus larvae through the soil

“…It is not possible to make a direct comparison between our work and that of AL SAQUR et al (1982) as they were working with a different host-parasite system in West Scotland under different climatic conditions. It is worth noting, however, that BORGSTEEDE & BOOGAARD (1983) working in the Netherlands with gastro-intestinal nematodes of cattle, including 0. ostertagi, found very few larvae in the soil and concluded that survival in the soil was negligible, this is in line with our observations, for the infective larvae of sheep gastro-intestinal nematodes.…”

“…It has been suggested that infective larvae of the cattle ncmatodc Ostertagia ostertogi can survive in the soil for several months and then migrate back on to the herbage in numbers sufficient to cause clinical disease in calves turned on to the pasture w the late summer (BAIRDHN et al 1979). Subsequently the ability of these infective larvae to survive for up to 12 months in the soil and reappear on the herbage at various times on a pasture not grazed during this time, was demonstrated by AL SAQUR et al (1982). They suggested that their observations provided evidence of a potential hazard to the successful implementation of control schemes in which such a rested pasture would be considered safe for grazing by calves in the late summer.…”

Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods

“…In contrast for method 2, the number of plucks taken and thus the amount of herbage collected, depends mostly on pasture area for method 1, however, no data is available on how magnitude of the herbage sample affects PLC results (Couvillion, 1993). Herbage samples collected by plucking contain more soil, which hinders L 3 recovery and identification (Crofton, 1954) and which can lead to unrepresentative larval counts, originating from the soil reservoir (Al Saqur et al, 1982;Callinan and Westcott, 1986;Demeler et al, 2012). Comparison of PLC obtained by tracer calves, the assumed golden standard, might be required to confirm a biological relevant difference between sampling methods.…”