Ivermectin and abamectin administered at different doses and routes against Cochliomyia hominivorax in the scrotum of newly castrated cattle from southeast region of Brazil/Ivermectina e abamectina em diferentes doses e vias de aplicacao contra larva s de Cochliomyia hominivorax em bolsas escrotais de bovinos recem-castrados, provenientes da regiao sudeste do Brasil

The preventive efficacy of ivermectin and abamectin administered in different routes (subcutaneous, intramuscular and pour-on) and doses (200 and 500mcg [kg.sup.-1]) against Cochliomyia hominivorax in the scrotal sac of cattle after castration, was evaluated. Animals from six different farms, in the state of Sao Paulo and Minas Gerais, Brazil were used. For each study, 3045 uncastrated bulls, depending on the number of groups, were selected. On day zero of the study, the procedure was carried out by the method of bloody castration and the animals were treated after this process. The efficacy of ivermectin and abamectin administered via the pour-on (500mcg [kg.sup.-1]), subcutaneous (200mcg [kg.sup.-1]) as well as the efficacy of abamectin intramuscularly (200mcg [kg.sup.-1]) were evaluated. In each experiment, one group of animals was kept as control. The animals were evaluated from the 3rd to the 14th day after castration process/treatment. The efficacy values for both active principles were