Abstract:
Relative resistance levels of cattle against tick infestations in the communal grazing area of Botshabelo
in the south-eastern Free State were determined. The objective was to establish whether differences
in resistance can be exploited to contribute to tick control methods used by small-scale farmers in
resource-poor environments. Ten cows (Bos taurus crosses) between the ages of 18 months and four
years were used and tick counts were conducted once a month over a period of 12 months to compare
their total tick burdens. Tick burdens of the various animals were compared mutually as well as
with the mean tick burden of the group as a whole. Tick numbers varied throughout the year on all
individuals but some animals consistently tended to have either higher or lower numbers than the
mean of the group. Tick burdens on cattle classified as having a relatively low resistance to tick infestations
increased eleven-fold from January to June 1996 compared to a six-fold increase on cattle
categorized as belonging to the high resistance group. Twenty-eight percent of the cattle in the total
study group carried 50% of the ticks collected (60 079). It is recommended that farmers in the region
visually assess B. decoloratus burdens, the most abundant tick species, and sell or cull the most susceptible
animals first in their normal program of utilization of the animals. This should eventually result
in the direct improvement of the overall tick resistance of their cattle herds.
