How hosts control worms

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

Herbage and stratified soil samples from a previously grazed calf pasture were collected regularly over a 12 month period (October 1979 to September 1980). Infective larvae of cattle Ostertagia spp (OL3) were present on each occasion to a depth of at least 15 cm. Analysis of the vertical distribution of the OL3 suggested a possible downward migration during the winter, followed by an upward trend in the spring and summer. The number of OL3 present in the root mat in august 1980 was estimated as 6.4 x 10(6) per hectare, a similar figure to that estimated for the previous November (6.6 x 10(6)) despite the absence of contamination during this period

Prediction model for bovine ostertagiasis

A mathematical model based on development and mortality rates, and incorporating data on the infectivity, fecundity and migratory behaviour of Ostertagia ostertagi, was used to predict the level of pasture contamination and the occurrence of clinical ostertagiasis in grazing calves during 1975 and 1976. A comparison of the predicted and observed events showed a good correlation

Comparison of 2 techniques used for the recovery of nematode infective larvae from pasture

The recovery of gastrointestinal nematode infective larvae from herbage collected manually was compared with the recovery from herbage ingested by sheep with oesophageal fistulae, on five occasions during the grazing season. At least three times more larvae were recovered from the oesophageal fistulates than by manual collection. There was no significant variation between the numbers of larvae collected at 09.00, 12.00 and 15.00, nor was there any difference in the distribution of genera recovered by the two methods. The worm burdens of tracer lambs and the larval counts from the fistulated sheep were used to estimate the rate of larval establishment

Benzimidazole resistance in nematodes of goats

Peer reviewe

Comparison of two techniques used for the recovery of nematode infective larvae from pasture

The recovery of gastrointestinal nematode infective larvae from herbage collected manually was compared with the recovery from herbage ingested by sheep with oesophageal fistulae, on five occasions during the grazing season. At least three times more larvae were recovered from the oesophageal fistulates than by manual collection. There was no significant variation between the numbers of larvae collected at 09.00, 12.00 and 15.00, nor was there any difference in the distribution of genera recovered by the two methods. The worm burdens of tracer lambs and the larval counts from the fistulated sheep were used to estimate the rate of larval establishment.Peer reviewe