Comparative clinical efficacy of fenbendazole and thiabendazole in feedlot heifers

Abstract

Heifers shedding eggs of nematodes or Moniezia were treated with either 5 mg/kg fenbendazole (FBZ) or 110 mg/kg thiabendazole (TBZ). 7 days later only trichostrongyle eggs were found (in 2 of 91 FBZ-treated heifers and 10 of 93 TBZ-treated heifers). The feedlot performances (average daily weight gain) were 0.75, 0.82 and 0.81 in the FBZ, TBZ and control groups, resp., over 34 days. The overall incidence of respiratory disease was 84 of 324 heifers used and was about equal in all 3 groups. Mortality was 4, 2 and 3 in the FBZ, TBZ and control groups, resp. Neither anthelmintic improved heifer performance.