The impact of natural infestations of ticks in Zambia on the productivity of cattle and implications for tick control strategies in central Africa

Studies were carried out in Zambia using a farming systems approach to quantify the effects of tick control on traditionally managed Sanga cattle. In the first trial to investigate the effect of tick control, significant improvements in liveweight gain (LWG) occurred only in periods of medium to high challenge with adult Amblyomma variegatum. However, during the first 18 months of the study when animals were young, the acaricide used caused a suppression in weight gains. A supplementary experimental study indicated that the adverse effects of ticks on weight gain may be delayed when animals are on a low plane of nutrition. In both studies on the effects of ticks on LWG, estimates of weight loss per female A. variegatum were in the range of 46 to 69 g. In the second long term trial to measure the impact of tick control on overall heard productivity, outputs of milk and weaner calf per livestock unit carrying capacity were about 25% higher in a tick-free herd. The annual cost of control in 1988 at ZK286.26/livestock unit was greater than the increase in value of the products at ZK175.48/livestock unit carrying capacity. It is concluded from these studies that intensive tick control in the multipurpose livestock system in Zambia is not justified in the absence of serious tick-borne disease. However, strategic seasonal tick control of adult ticks from November to April would probably be economically viable. Calves should not be treated until they are 3 months of age.