Abstract
The high prevalence of resistance of Haemonchus contortus to all major anthelmintic groups has prompted investigations into alternative control methods in South Africa, including the use of copper oxide wire particle (COWP) boluses. To assess the efficacy of COWP against H. contortus in indigenous South African goats, 18 male faecal egg-count-negative goats were each given ca.1200 infective larvae of H. contortus three times per week during weeks 1 and 2 of the experiment. These animals made up an “established” infection group (ESTGRP). At the start of week 7, six goats were each given a 2-g COWP bolus orally; six goats received a 4-g COWP bolus each and six animals were not treated. A further 20 goats constituted a “developing” infection group (DEVGRP). At the beginning of week 1, seven of the DEVGRP goats were given a 2-g COWP bolus each; seven goats were treated with a 4-g COWP bolus each and no bolus was given to a further six animals. During weeks 1–6, each of these DEVGRP goats was given ca. 400 H. contortus larvae three times per week. All 38 goats were euthanized for worm recovery from the abomasa and small intestines in week 11. In the ESTGRP, the 2-g and 4-g COWP boluses reduced the worm burdens by 95% and 93%, respectively compared to controls (mean burden±standard deviation, SD: 23±33, 30±56 and 442±518 worms, P=0.02). However, in the DEVGRP goats, both the 2-g and 4-g COWP treatments were ineffective in reducing the worm burdens relative to the controls (mean burdens±SD: 1102±841, 649±855, 1051±661 worms, P=0.16). Mean liver copper levels did not differ between the ESTGRP goats treated with 2-g COWP, 4-g COWP or no COWP (mean±standard error of the mean, SEM, in ppm: 93.7±8.3; 101.5±8.3; 71.8±8.3, P=0.07) nor did they differ between the DEVGRP goats (mean±SEM, in ppm: 74.1±9.1; 75.4±9.1; 74.9±10.0, P>0.99). The copper values were considered adequate, but not high, for goats. The COWP boluses have the potential to be used in the place of conventional anthelmintics for the control of established H. contortus infections in indigenous South African goats, but their use as part of an integrated approach to control H. contortus in the field must be fully investigated.
Highlights
Haemonchus contortus is a major constraint to the production of sheep and goats in the tropical and subtropical regions of the world and causes substantial economic losses to small-scale farmers (Perry et al, 2002)
7200 larvae were administered per goat but the percentage establishment per group was approximately 6% for the established” infection group (ESTGRP) controls and 15% for the developing” infection group (DEVGRP) controls
Burke et al (2004) demonstrated reductions of 90%, 94% and 93% of 4-week-old H. contortus infections in lambs, with doses of 2 g, 4 g and 6 g copper oxide wire particle (COWP), respectively
Summary
Haemonchus contortus is a major constraint to the production of sheep and goats in the tropical and subtropical regions of the world and causes substantial economic losses to small-scale farmers (Perry et al, 2002). Control of the parasite is complicated by the presence of widespread resistance to the available anthelmintic groups (Vatta and Lindberg, 2006) This has prompted investigations into alternative methods of control (Waller, 2006; Torres-Acosta and Hoste, 2008), of which treatment with copper oxide wire particles (COWP) is attracting considerable research interest (Burke et al, 2007a,b). Developed initially to overcome copper deficiency in grazing ruminants (Dewey, 1977; Suttle, 1981), the COWP-containing bolus releases particles in the rumen. These move distally through the gut of the animals to lodge in the mucosal folds of the abomasum. Several workers have examined the prophylactic effect of COWP in preventing the establishment of infective larvae of H. contortus, but the efficacy of the treatments has varied (Knox, 2002; Chartier et al, 2000; Martínez Ortiz de Montellano et al, 2007)
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