A total of 75 crossbred steers were divided into 15 pastures of five animals each. One animal from each pasture was randomly assigned to one of five groups. Cattle were then administered their assigned treatment (or left untreated for the control group). All cattle had an equal chance of being re-infested with parasites.
Cattle grazed for 112 days, from winter to summer. Body weight was measured throughout the study. After 112 days, final body weight was measured in all groups.