A field trial was conducted with 80 cow-calf pairs to evaluate the effect
of deworming both cows and calves with fenbendazole, on cattle performance and
internal parasite burden. Midseason and weaning weights of calves in the
fenbendazole-treated group averaged 22.4 and 33.5 lb heavier (P<.04), respectively,
than controls. Cow and calf fecal egg counts were low throughout the grazing
season and were not materially affected by treatment.