EFFICACY OF MOXIDECTIN, IVERMECTIN AND ALBENDAZOLE ORAL DRENCHES FOR SUPPRESSION OF PERIPARTURIENT RISE IN EWE WORM EGG OUTPUT AND REDUCTION OF ANTHELMINTIC TREATMENT FOR LAMBS

Sixty multiparous crossbred ewes which had lambed within three days in the first week of April 1996, were divided into four groups. Each gro up consisted of 15 ewes plus 12 pairs of twins and three single lambs, Group 1 was left untreated, group 2 was treated with albendazole 2.5 per cent drench, group 3 received moxidectin 0.1 per cent drench and g roup 4 received ivermectin 0.08 per cent drench, The ewes in each grou p were dosed with their anthelmintic on April 4 (day 0) before being t urned out to separate equal-sized paddocks within the same field on th e following morning. The field had been used for grazing sheep annuall y for many years and was considered to be contaminated with infective larvae of the common gastrointestinal nematodes infecting sheep in the region, Faecal samples were collected every two weeks from the ewes a nd lambs until July 25 (day 112). The lambs in each group were dosed w ith the anthelmintic used for their darns on day 42, and the dose was repeated when more than 50 per cent of the lambs in any group had a fa ecal egg count of more than 200 eggs per gram (epg), The total faecal egg output of the treated ewes over days 14 to 70, compared with that of the untreated control group, was reduced by 78.9 per cent by the mo xidectin drench, by 47.6 per cent by ivermectin, and by 21.5 per cent by albendazole. The lambs in the groups treated with moxidectin and iv ermectin required only one treatment on day 42 before reaching finishi ng weight; those in the albendazole-treated group were treated twice a nd the control group once. The faecal egg outputs of the lambs from da y 42 until the end of the experiment on day 112 were reduced by 75 per cent by the moxidectin drench, by 48.5 per cent by ivermectin, and by 9 per cent by albendazole. There were no significant differences betw een the rates of weight change of either ewes or lambs in any of the g roups.