The blood volumes and erythrokinetics of Ndama and Zebu cattle experimentally infected with Trypanosoma brucei

The responses of susceptible Ndama and Zebu cattle to experimental infection with Trypanosoma brucei were compared using haematological, parasitologies! and radioisotopic methods. Animals of both breeds became anaemic, but this was more severe in the Zebu cattle, one of which died. Although the prepatent period was the same in animals of both breeds, the levels of the first and subsequent peaks of parasitaemia were higher in the Zebu. The anaemia was due to an accelerated rate of red cell breakdown which was more marked in the Zebu cattle. Haemo- dilution was not a feature. There was no evidence of dyshaemopoiesis but iron réutilisation from degraded erythrocytes was impaired. The greater resistance of the Ndama to T brucei infection could not be attributed to the capacity of this breed to mount a more effective erythropoietic response than the Zebu.