Abstract
A study was conducted to examine the duration of anthelmintic effect of copper oxide wire particles (COWP) in grazing goats, as data for the persistence of efficacy of COWP in this host species is limited. Forty-eight indigenous male goats were infected naturally by grazing them on Haemonchus contortus-infected pasture. When the faecal egg count (FEC) in the goats was 3179±540 eggs per gram of faeces (mean±standard error), half the animals were treated with 4g COWP (day 0; mean live weight=25.5±0.8kg). Eight treated (COWP) and eight non-treated (CONTROL) goats were removed from the pasture on each of days 7, 28 and 56, maintained for 27 or 29 days in concrete pens and then humanely slaughtered for nematode recovery. Mean liver copper levels were in the high range in the goats removed from pasture at day 7 (treated: 191±19.7ppm; untreated: 120±19.7ppm; P=0.022), but had dropped to normal levels at days 28 and 56. The mean H. contortus burdens of the treated versus the non-treated goats were, respectively, 184±48 and 645±152 for the goats removed from pasture at day 7 (71% reduction; P=0.004), 207±42 and 331±156 at day 28 (37% reduction; P=0.945) and 336±89 and 225±53 at day 56 (−49% reduction; P=0.665). Weekly monitoring of FECs after treatment until slaughter indicated that the COWP-treated goats had lower FECs than the controls, the treatment main effect being significant at days 7, 28 and 56 (P<0.01). The day main effect and the treatment×day interaction were only significant for the goats removed from pasture at day 28 (P≤0.001). Packed cell volumes increased during the course of the experiment (day, P<0.001), but the treatment main effect was significant only for the goats removed from pasture at day 28 (CONTROL 28 d, 28.65±0.52%<COWP 28 d, 31.31±0.52%; P<0.001). No differences in live weight between groups were considered to be of any practical significance. The study indicated that persistence of efficacy of COWP is limited in goats, extending at most to 28 days after treatment. However, repeated COWP administration at three-month intervals may be safe, given that liver copper levels return to normal two to three months after COWP treatment.
Highlights
Disease caused by Haemonchus contortus is one of the major constraints to the production of sheep and goats in the tropics and subtropics, and causes substantial losses to farmers worldwide
Investigations have focused on copper oxide wire particles (COWP) which have been shown to have an anthelmintic effect against abomasal nematodes, H. contortus (Bang et al, 1990)
Mean liver copper levels tended to be higher in the treated goats than in the controls removed from pasture 7 days post treatment and slaughtered 28 days later (P = 0.022; Table 2), but did not differ in the goats removed
Summary
Disease caused by Haemonchus contortus is one of the major constraints to the production of sheep and goats in the tropics and subtropics, and causes substantial losses to farmers worldwide. Investigations have focused on copper oxide wire particles (COWP) which have been shown to have an anthelmintic effect against abomasal nematodes, H. contortus (Bang et al, 1990). They represent a potentially cheap alternative to anthelmintics for small-scale farmers in the developing world, if the use of COWP can be successfully integrated into worm control programmes. One study (Galindo-Barboza et al, 2011) has examined the persistence of efficacy of COWP based on worm counts in sheep. No worm count data are available on the duration of efficacy of COWP in groups of goats subjected to similar levels of parasite exposure, nutrition and management. The present study sought to examine the effect of COWP treatment in goats treated and removed from infective pasture at three different stages, namely at 7, 28 and 56 days post treatment
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