EVALUATION OF DORAMECTIN IN A PROGRAM FOR SEASON-LONG CONTROL OF PARASITIC GASTROENTERITIS IN CALVES

Doramectin was used in a strategic programme for the prevention of par asitic gastroenteritis in first season grazing calves, Three groups of nine calves were used: group 1 was left untreated, group 2 was treate d with doramectin at 0.2 mg/kg at turnout and again eight weeks later, and group 3 was treated with 0.2 mg/kg ivermectin at three, eight and 13 weeks after turnout, Both treatment programmes prevented the gastr oenteritis which occurred in the controls. The growth rates of the tre ated calves were superior, and their faecal egg output, and serum peps inogen and gastrin concentrations were all substantially lower than th ose of the control calves. The numbers of Ostertagia species larvae on the pastures grazed by the treated calves were also lower than on the pastures grazed by the control calves.