Effect of strategic deworming of village cattle in Uganda with moxidectin pour-on on faecal egg count and pasture larval counts

Strategic application of moxidectin pour-on (Cydectin) was evaluated in Uganda for its effect on pasture larval counts and gastrointestinal nematode faecal egg counts in village cattle kept under tethering (semi-intensive) grazing management. The strategic deworming schedule involved treating cattle twice at an interval of 2 months, at the end of the 1st wet season and during the 2nd wet season. Two groups of 30 cattle, each consisting of a treated and a control group, were examined for nematode infections every 4 weeks from June 1999 to January 2000. The treated group had significantly lower mean faecal egg counts than the untreated groups (t-value = 2.47, P < 0.05). Generally, the pasture larval counts on treated farms were lower than on untreated ones, but not significantly so (t-value = 2.22, P = 0.068). Pasture larval counts with different nematode species on treated farms were lower than on untreated ones, but the differences were not significant for Haemonchus spp. (t-value = 1.68, P = 0.145), Oesophagostomum spp. (t-value = 1.87, P = 0.111), Trichostrongylus spp. (t-value = 1.93, P = 0.102), Dictyocaulus spp. (t-value = -0.74, P = 0.485) and Cooperia spp. (t-value = -1.00, P = 0.356). Treated farms did, however, have significantly lower pasture larval counts of Bunostomum spp. (t-value = 4.64, P < 0.05). This study has revealed that the application of moxidectin pour-on on cattle has an effect on faecal egg count and pasture contamination under the tethering grazing system. Moxidectin pour-on and the strategic deworming schedule evaluated here could be used for the control of gastrointestinal nematode infections in cattle by small-scale farmers who practise tethering or semi-intensive grazing management in Uganda and other tropical countries, especially where there is a bimodal rainfall pattern.