Prevalence of anthelmintic resistance in gastrointestinal nematodes of dairy goats under extensive management conditions in southwestern France

Abstract

The occurrence of benzimidazole (BZ) and levamisole resistance was investigated in 18 randomly selected dairy goat herds located in southwestern France and characterized by extensive management. On each of the 18 farms, 45 adult goats were randomly allocated into three groups of 15 animals each: an untreated control group, a group that was orally administered fenbendazole (10 mg kg-1 body weight) and a group that received orally a levamisole drench (12 mg kg-1 body weight). Individual faecal egg counts and pooled larval cultures were done 10 days after anthelmintic treatment. Naive lambs were infected with larvae obtained from control and fenbendazole treated groups and were necropsied 35 days after infection for worm recovery. Faecal egg count reductions (FERC) were calculated for fenbendazole and levamisole and, when less than 95 per 100, were considered as indicative of anthelmintic resistance. An in vitro egg hatch test (EHT) was conducted with thiabendazole on eggs isolated from pooled faeces of fenbendazole treated goats in nine farms. Faecal egg count reductions indicated the occurrence of benzimidazole resistance in 15 out of 18 farms. Among these farms, nine had EHT values above 0.1 μg thiabendazole ml-1 confirming the benzimidazole resistance status. Levamisole resistance was detected in two farms through FECR. Based on necropsy results, the prevalence of benzimidazole resistance was higher in Trichostrongylus colubriformis, medium in Haemonchus contortus and lower in Teladorsagia circumcincta. In nine farms the benzimidazole resistance was monospecific whereas multispecific resistance was found in the six remaining farms. A negative relationship was found between FECR for fenbendazole and the average number of anthelmintic treatments given per year on the farm. Despite extensive management including a low number of treatments, the prevalence of benzimidazole resistance was very high suggesting that the repeated and sometimes exclusive use of benzimidazole drugs, even at low frequency, is probably the main cause in developing nematode resistance in dairy goat herds. The importance of other factors such as under-dosing or buying animals already carrying resistant nematodes are discussed.

Anthelmintic efficacy of aqueous extract of Zanthoxylum armatum DC. seeds against Haemonchus contortus of small ruminants

“…Both the minerals have role in blood formation as well as in body defense through activation of various enzymes of synthetic and defense activity. The recent studies have shown that copper administered orally to sheep and goats has an anthelmintic effect against H. contortus with extended protection up to 8 weeks (Chartier et al 2001, Waruiru et al 2004, Burke et al 2005. A similar study shows that copper treatment or supplementation reduced female worm length, number of eggs in utero and prolificacy of H. contortus resulting into reduced pasture infectivity (Martinez Ortis-de Montellano et al 2007).…”

Sheep and goat nematode resistance to anthelmintics: pro and cons among breeding management factors

“…Data allowing the comparison of the species composition of the nematode parasite community before and after anthelmintic resistance development are necessary to substantiate this statement. Published data on anthelmintic resistance reports seem to indicate that on the world scale, H. contortus is the species the most prone to develop anthelmintic resistance [10] and T. colubriformis presents the highest benzimidazole resistance level in southwestern France [25].…”

Administration of Duddingtonia flagrans chlamydospores to goats to control gastro-intestinal nematodes: dose trials

“…Two recent surveys conducted in Poitou-Charentes and Midi-Pyrénées in France [5,6] reported that almost 100% of investigated farms presented nematodes 158 C. Paraud et al resistant to benzimidazoles. On the other hand, organic farming where the use of chemicals is reduced is increasing in popularity due to consumer demands.…”