The effects of host resistance on the pick-up rates of ticks under natural infestation in Uganda
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OAU/STRC Bulletin of Animal Health and Production in Africa;45(1): 17-26
Permanent link to this item: http://hdl.handle.net/10568/29293
The pick-up rates of tick species by various resistant groups of animals, dipped once a month and not dipped were investigated under ranch conditions in Nabiswera, Luwero district, Uganda. During the first three weeks of exposure of cattle to natural tick infestation, two phases of tick build-up and one phase of decline in tick population were demonstrated with R. appendiculatus. The other tick species were too few for comparisons to be made. Each of these phases lasted about 7 days, except on animals dipped once a month where the phase of decline in tick population lasted only 3 days. These fluctuations in pick-up rates were attributed to differences between drop-off rhythms of engorged female ticks and reinfestation pressure of unfed ticks. The peak numbers of R. appendiculatus were determined by the carrying capacity of the ears of animals. After three weeks of exposure, the population of R. appendiculatus on cattle stabilized and this could be due to the attainment of an equilibrium balance between drop-off rhythms and reinfestations. The pick-up rates were highest on the low resistance (LR) groups of animals, followed by the medium resistance (MR) and was lowest on the high resistance groups (HR). These patterns of tick infestation were identical in both treatment groups of animals. The significance of using pick-up rates of ticks for differentiating the levels of host resistance in cattle are discussed.