Tick infestations and their effects on growth of Bos indicus × Bos taurus cattle in the wet tropics

Abstract

The effects of bi-monthly dipping with Promacyl and no dipping on tick numbers and liveweight gain of young Bos indicus x Bos taurus cattle grazing tick infested improved pastures were compared in three experiments over three years at Utchee Creek, northern Queensland. Reduction in weight gains, due to ticks, of 24 and 30 kg (P<0.01) were measured over 11 and 17 months. Tick counts on undipped cattle were low (0-40/side) but rankings of tick counts on individual animals were repeatable (0.4-0.60). Liveweight gains of undipped cattle were unrelated (P> 0.05) to mean tick counts. When cattle were changed from an undipped to dipped treatment, they gained 18 kg more (P < 0.01) over six months than those changed from dipped to undipped. The latter groups carried more ticks than corresponding undipped cattle in the first two experiments.