Effect of ivermectin on the reproductive potential of Cooperia curticei
McKellar, Q.A.; Bogan, J.A.; Horspool, L.; Reid, K.
Veterinary Record 122(18): 444
1988
ISSN/ISBN: 0042-4900 PMID: 3394239 Document Number: 321196
Of 4 groups of Blackface lambs (3 lambs/group) experimentally infected with C. curticei, 2 groups were treated with ivermectin 28 days after infection and 2 groups (controls) were untreated. Two groups (one control and one treated) were killed 7 days after treatment and the two other groups 14 days after treatment. When worm numbers were estimated from the 4 quarters of the small intestine, anthelmintic efficacies of 61.1% and 90.4% were seen after 7 and 14 days, respectively. A much larger proportion of worms survived treatment in the distal parts of the intestine. When female worms were examined it was shown that those worms that had been exposed but had survived ivermectin treatment had an average of 0.7 eggs in their uteri compared with 21.6 eggs in the uteri of worms in control animals. It is suggested that these worms will have a poor reproductive potential and will make an insignificant contribution to pasture contamination.