Factors affecting estimation of tsetse challenge and the expression of trypanotolerance

Factors affecting the expression of trypanotolerance are discussed. Some of the factors which could influence the feeding preference of tsetse are physical - skin thickness, skin rippling; visual - coat colour, size; olfactory - breath, urine, skin secretions; behaviour - tail flicking, head swings. It is suggested that whilst there are lower transmission potentials between trypanotolerant livestock and tsetse, the main differences between trypanotolerant and trypanosusceptible breeds of livestock are found in the way in which different cattle deal with the trypanosomes that are transferred during the bite of an infected tsetse.