Production, parasitological and carcase evaluation studies in steers exposed to trichostrongyle infection and treated with a morantel bolus or fenbendazole in two consecutive grazing seasons

Friesian steers were exposed to natural trichostrongyle infection and left untreated (controls) or treated with either a morantel sustained release bolus or fenbendazole at two week intervals (clean) in each of two consecutive grazing seasons. In the second grazing season the mean liveweight gains of the clean, morantel treated and control groups of cattle over 152 days were 105, 131 and 109 kg respectively (morantel treated > clean, control P