RESUMO
Endo- and ectoparasite infections are among the most important causes of disease and production losses in beef cattle in tropical and subtropical regions. Nevertheless, most treatments are given without epidemiological information and without evaluating their effect on the development of the animals. In this work we present the results of a study of the effect of treatments against endo- and ectoparasites in crossbred steers, during three cycles of field trials in the Brazilian Cerrado region. Three anthelmintic treatments during the winter and three acaricidal treatments during the spring/summer provided significant additional weight gain in three and two experimental trials, respectively. In the trials, steers treated for gastrointestinal nematodes gained a mean of 33 kg more and those treated for ectoparasites had additional mean weight gains of 13 kg compared with non-treated steers.