Strategic timed used of fenbendazole deworming blocks in stocker cattle

Abstract

Groups of 25 cattle were treated with fenbendazole (Panacur, 5 mg/kg) by oral drench (group I) or ivermectin (Ivomec, 200 µg/kg) subcutaneously (group II) before being turned out on separate pastures known to be contaminated with helminth larvae. Group I animals were provided with fenbendazole-medicated blocks (Safeguard Dewormer Block, designed to deliver 5 mg/kg fenbendazole over 3 days) for 3 days from day 21 after grazing began and from day 42. Group II animals had access to similar blocks for 8 days from 35 days after grazing began; the animals in both groups had been trained to use the blocks. The average weight gain over the whole trial period (111 days) was significantly larger in both groups of treated animals than in controls (15 untreated animals). From days 29 to 72 of the trial, group I animals gained significantly more weight than group II animals. Egg counts in treated animals were significantly lower than in controls from days 29-72, and serum pepsinogen levels were lower in group I animals than in group II animals at the end of the trial. Pasture larval counts were highest in pastures grazed by controls and lowest in those grazed by group I animals.