Trypanotolerance in small ruminants of sub-Saharan Africa.

Although a lot of information is currently available on trypanotolerance in cattle, until recently the trypanotolerant nature of small ruminants was not well known. Trypanotolerance in small ruminants is less pronounced than in cattle and should be considered as resilience rather than resistance. West African Dwarf (WAD) goats seem to be less trypanotolerant than Djallonke sheep. However, recent studies have shown that there is an important introgression of genes of trypanosusceptible breeds into WAD goat populations, which possibly explains the loss of trypanotolerance in these animals. Measures need to be taken to safeguard and upgrade the genetic purity of trypanotolerant goat and sheep breeds in Africa.