Abstract:

The effect of moxidectin on the prevalence of nematode infection in cattle,
fecal egg output and pasture contamination of common pastures was assessed
in Tororo district, Uganda. In the first experiment, a treated and an untreated
group of 40 head of cattle each were monitored for a period of 12 weeks,
while in the second experiment a treated and an untreated group of 30 head
of cattle each were monitored for seven months. In the first experiment, the
prevalence of nematode infections and mean fecal egg count (FEC) of the
treated group remained significantly (P < 0.05) lower than that of the
untreated group from day 7 to 84. In the second experiment, strategic
treatments initially led to 100% reduction of FEC in the treated cattle as
compared to 82% in the untreated one. Thereafter, mean FEC in the treated
cattle remained below 60 for six months, while that in the untreated cattle
fluctuated between 63 and 400, depending on the amount of rainfall. In
addition, contamination with infective larvae on pasture of the treated cattle
was significantly (P < 0.05) lower than that of the untreated group during the
wet season. Infestation with Haemonchus spp., Bunostomum spp.,
Oesophagostomum spp. and Trichostrongylus spp. was three-, five-, four- and
two-fold lower, respectively, on pasture in treated than in untreated cattle.
Moxidectin could be used in strategic parasite control under communal
grazing management in tropical Africa by selective treatment of the most
affected cattle age-groups during the middle and end of the wet season to
reduce the level of pasture contamination