EFFICACY OF MICHELS DOSE-AND-MOVE SYSTEM AGAINST DICTYOCAULUS-VIVIPARUS INFECTIONS IN CATTLE USING MOXIDECTIN AS ANTHELMINTIC

Two grazing experiments were performed to study the effect of moxidect in in a 'dose and move' system on Dictyocaulus viviparus infections in calves. In the first experiment, three groups of four calves were exp erimentally infected with 20 larvae of D. viviparus 7 weeks before mox idectin treatment of two of these groups, A sufficient suppression of Dictyocaulus infections was observed in a 'dose and move' group, but a lso in a group which stayed on contaminated pasture after treatment. I n contrast, high faecal larval counts and lungworm disease were observ ed in July-August in a nontreated pasture control group, Development o f immunity against lungworm was sufficient in all three groups on past ure, In the second experiment, four out of 16 calves, including two gr oups of six calves and four tracer calves, were experimentally infecte d with 20 larvae of D. viviparus 7 weeks before moxidectin treatment c ombined with a move of one of the groups, No lungworm disease was obse rved in this 'dose and move' group, In a pasture control group high fa ecal larval counts and severe clinical disease were observed in August -September and one calf had to be euthanized. Although a mean burden o f 129 immature lungworms was present at the time of treatment, develop ment of immunity appeared to be low in the 'dose and move' group, In c ontrast, high levels of immunity had developed in the pasture control group.