Practices and efficacy of nematode control in sheep, goats and cattle in communal grazing settings of central Ethiopia

Communal grazing is the predominant farming system in Ethiopia and the livelihood of millions of people depend on it. Gastrointestinal nematodes represent a serious threat to the sustainability of these systems, and there is further concern due to the worldwide spread of anthelmintic resistance (AR). This study aimed to assess nematode control practices and anthelmintic efficacy in three districts of central Ethiopia, where sheep, goats and cattle are reared together by resource-poor farmers. A total of 153 farmers were interviewed and 36 faecal egg count reduction tests (FECRTs) were conducted for each ruminant species grazing in the communal pastures, comprising a control group and three treatment groups (albendazole ABZ, tetramisole TET and ivermectin IVM) for each district. The questionnaire survey indicated that nematode control relies on poor practices and is substantially based on pharmacological treatments. About 91.8% of animals are treated at least twice a year often in absence of clinical signs and by untrained farmers, with no monitoring nor drug rotation implemented. In the FECRT-based survey, susceptibility to TET was confirmed in all trials, while treatment failure was a consistent finding for ABZ. IVM showed inefficacy in cattle and, to a lesser extent, in goats, while it was always effective in sheep. Research on AR in African countries is focused on small ruminants but in this study cattle had the worst results in terms of the number and severity of ineffective treatments, suggesting their inclusion in future studies on AR in this type of settings.