Methods to improve the health of cattle in the tropics: conclusions and economic appraisal.

The results of the immune responses of immunised and chemoprophylactically treated calves to tick-borne (Boophilus microplus) challenge indicate that the system of immunisation was effective in protecting cattle against Anaplasma marginale, Babesia argentina (bovis), and B. bigemina. However, chemoprophylaxis was effective only against Babesia spp. but not against A. marginale. Both methods showed a substantial advantage over no control system when using native cattle breeds in a zone endemic for bovine anaplasmosis and babesiosis. Based on the net economic gain per calf starting the experiment, sizeable differences were noted at 308 days between the calves in the immunised group, chemoprophylaxis group, tick and gastrointestinal parasite control group and the experiment control group.