A technique for the recovery of nematodes from ruminants by migration from gastro-intestinal ingesta gelled in agar: large-scale application.

A gelled-agar technique for worm recovery was adapted to facilitate the recovery of larval and adult nematodes from the total ingesta of large numbers of sheep. The technique was also used to recover nematodes from 4 calves. In one trial involving 120 sheep, 100% of 2013 4th stage larvae (L4) and 92,1% of 134,205 adult Haemonchus contortus migrated from the agar preparations. Highly significantly more male than female worms failed to migrate. Using 1 x 1/10 aliquot to estimate the numbers of worms that failed to migrate from the agar, the mean error in the total worm count (worms that migrated plus those that failed to migrate) per sheep was 2,2%; with an examination of 2 x 1/10 aliquot the error was 1,7%. We concluded from this that the gelled-agar method may be of value for quantitative worm recovery, for example, in anthelmintic tests. In a second trial, 98,5% of 17,056 L4 and adult nematodes of 5 genera migrated from the ingesta of 4 calves and 96,4% of 62,597 L4 and adult nematodes of 9 species from the ingesta of 15 sheep. In general, L4 migrated slightly more efficiently than adult worms. In sheep and, to a lesser extent, in calves, Haemonchus spp. did not migrate as efficiently as the other genera such as Ostertagia, Trichostrongylus, Nematodirus, Oesophagostomum, Marshallagia and Chabertia.