SINGLE-DOSE OF DORAMECTIN TO CONTROL GAST ROINTESTINAL HELMINTH INFECTION AT TURN-OUT OF THE 2ND GRAZING SEASON - RESULTS OF 2 FRENCH TESTS

Two studies were conducted in France in 1993 to determine the efficacy of a single injection of doramectin administered at turn-out, in cont rolling parasitic gastro-enteritis (PGE) in second season grazing catt le. Treated animals were compared to control animals individually trea ted, at mid-season, with a short acting anthelmintic drug. Treated and control cattle were set stocked on two identical but separate areas c oming from the split of a single pasture. Criteria for comparison were weight gains, cumulative fecal egg counts and herbage larval counts. In the two trials, no clinical signs of PGE were seen in either group. Cumulative strongyle egg shedding, although low for this type of catt le, was reduced for treated animals compared to control animals. In on e trial, the infestation of the doramectin pasture remained low during automn, compared to the control pasture. This was not seen in the oth er trial. The weight gains of doramectin treated animals were greatly improved compared with the control groups; at the end of the trials, t he average differences between treated and control groups were 35 kg i n one trial and 44 kg in the other. The weight gain difference occured particularly at the beginning and at the end of the grazing season.