Effects of treatments with endectocide on the weight gain of grazing cattle in a warm temperate climate

Five groups of 20 weaned beef calves were injected subcutaneously with eith er an ivermectin, a doramectin, an abamectin long-acting formulation, an iv ermectin long-acting formulation or a saline control, at turnout and 60 and 120 days later. The animals grazed the same pasture and were sampled and w eighed at turnout and 30, 60, 90,12o, 150 and 180 days later. At turnout th e mean bodyweights of all the groups were similar and faecal culture showed that they had a mixed strongyle infection of Cooperia, Haemonchus, Osterta gia, oesophagostomum and Trichostrongylus species. After 180 days, the mean bodyweight gains of each group were respectively 62.1 kg, 102.2 kg, 106.4 kg, 107.3 kg and 110.1 kg for the control, ivermectin, doramectin, ivermect in long-acting and abamectin long-acting groups. All the products significa ntly improved the weight gains of the cattle, and significantly reduced the ir faecal egg counts.