THE EFFECTS OF THE BROWN EAR-TICK, RHIPICEPHALUS-APPENDICULATUS, ON MILK-PRODUCTION IN DAIRY-CATTLE

The effect is reported of artificially controlled levels of infestatio n with adults of Rhipicephalus appendiculatus on the milk yield of twe nty commercial Bos taurus dairy cattle on a high plane of nutrition an d eighteen crossbed B.taurus x Sanga cattle on a lower plane of nutrit ion in the highveld of Zimbabwe. The results showed no significant eff ect on milk yield of infestations averaging twenty engorging ticks per animal per day, despite severe ear damage in some animals. They indic ate that milk production of dairy cattle under commercial management i s not sensitive to infestation with R.appendiculatus. The results have important implications for management of ticks in Africa, but need to be interpreted within the context of the control of tick-borne diseas es.