Comparison of the persistent activity of ivermectin, abamectin, doramectin and moxidectin in cattle.

摘要

Six studies involving 330 cattle were conducted in Argentina, Brazil and Colombia to compare the efficacy of injectable endectocides in cattle grazing naturally infested pastures. Cattle were ranked either by weight or faecal egg count into single sex blocks and within blocks were randomly allocated to treatment with moxidectin, doramectin, abamectin or ivermectin (all by subcutaneous injection at 1 ml/50 kg, equivalent to a minimum of 200 mug of active ingredient/kg bodyweight) or to be an untreated control. Throughout the 9 week post-treatment period, the cattle of each treated group had significantly lower faecal egg counts than the untreated controls. Although the moxidectin group had higher egg counts until 5 weeks after treatment, from 6 weeks after treatment there was no significant differences among the treated groups. Compared with the untreated controls, the reductions in mean cumulative faecal egg counts were 96%, 97%, 95% and 96% for the moxidectin, doramectin, abamectin and ivermectingroups, respectively. The major parasite challenge was from Cooperia and Haemonchus spp.; Ostertagia, Trichostrongylus and Oesophagostomum spp. were also identified. It was concluded that there are no practical differences in the persistent activity ofthe injectable endectocides studied in the control of naturally acquired bovine gastrointestinal parasites.