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McMahon C.,Queens University of Belfast | Bartley D.J.,Moredun Research Institute | Edgar H.W.J.,Agri Food and Biosciences Institute AFBI Stormont | Ellison S.E.,Queens University of Belfast | And 5 more authors.
Veterinary Parasitology | Year: 2013

The prevalence of anthelmintic resistance in Northern Ireland sheep flocks was evaluated between July and October 2011. Sampling kits were sent to 172 flock owners and returns were received from 91. Within this survey population, 27 flock owners used benzimidazole products, 10 used levamisole products, 15 used avermectin products, 26 used milbemycin products and 4 flock owners used the amino acetonitrile derivative, Monepantel. The remaining 9 flock owners used combination drenches (broad spectrum wormer plus fasciolicide). However, 15 sets of samples were ineligible for faecal egg count reduction testing due to either too low an egg count or insufficient faecal volume.Treatment efficacy below 95%, indicating significant resistance, was detected in 81% (. n=. 24) of flocks tested for benzimidazole resistance; in 14% (. n=. 1) of flocks tested for levamisole resistance; and in 50% (. n=. 7) and 62% (. n=. 13) of flocks tested for avermectin and milbemycin resistance, respectively. Monepantel resistance was absent in all (. n=. 3) flocks tested.Combination products (broad spectrum nematocide plus flukicide) containing levamisole were entirely effective, while treatment efficacy below 95% was detected in 60% (. n=. 3) of flocks where the nematocide in the combination product was a benzimidazole. Where parasite identification based on coproculture was completed, Trichostrongylus was the dominant genus detected in all cases post-treatment, indicating the occurrence of anthelmintic-resistant Trichostrongylus spp. populations. Benzimidazole efficacy was highest in treating Trichostrongylus spp. (51%) and lowest when treating Teladorsagia spp. Levamisole was 100% effective in treating Cooperia, but ineffective (0%) in treating Trichostrongylus spp. Avermectin efficacy was highest when treating Haemonchus contortus (100%) and Teladorsagia spp. (73%), with a marginally lower efficacy against Trichostrongylus spp. (71%). Moxidectin efficacy was 33% against Trichostrongylus spp., 68% against Teladorsagia spp., 97% against Cooperia spp. and 100% against Haemonchus contortus infections. © 2013 Elsevier B.V. Source

McMahon C.,Queens University of Belfast | Barley J.P.,Agri Food and Biosciences Institute AFBI Stormont | Edgar H.W.J.,Agri Food and Biosciences Institute AFBI Stormont | Ellison S.E.,Queens University of Belfast | And 4 more authors.
Veterinary Parasitology | Year: 2013

A questionnaire to obtain information on nematode control practices and sheep management was sent to over 1000 farmers in Northern Ireland. Replies were received from 305 flock owners, and data from 252 of them were analysed. Farms were divided into lowland and upland areas. Sizes of pasture and stocking rates on lowland and upland farms were 59.5 hectares, 6.99 sheep/hectare and 62.9 hectares and 10.01 sheep/hectare, respectively. Mean drenching rates for lambs and adults were 2.33 and 2.44, respectively, in lowland flocks and 2.73 and 2.71, respectively, in upland flocks. Between 2008 and 2011, the most frequently identified compounds in use were benzimidazoles and moxidectin in lowland flocks, and benzimidazoles and avermectins in upland flocks. Over the same period the most frequently identified commercial formulations were Tramazole®, Panacur® and Allverm® (white drench), Levacide® (yellow drench), Oramec® (clear drench; avermectin), Cydectin® (clear drench; moxidectin) and Monepantel® (orange drench).Most respondents (56.35%) treated their lambs at weaning and the most common time to treat ewes was identified to be pre-mating (67.86% of respondents).The results of the questionnaire survey revealed that lowland annual drench frequency was 2.33 and 2.44 in lambs and ewes, respectively, although drench frequencies were higher in upland flocks: 2.73 and 2.71 for lambs and ewes, respectively.Annual drench rotation was practiced by 43.96% of flock owners, but whether this was true rotation or pseudo-rotation (i.e., substitution of one anthelmintic product by another product belonging to the same chemical group of anthelmintics) could not be explicitly determined. © 2012 Elsevier B.V. Source

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