COW CALF HERD INVESTIGATION - FENBENDAZOLE IN A STRATEGIC DEWORMING PROGRAM/

A 2-year study on the economics of strategic deworming in a cow/calf o peration was conducted in the Great Basin. Hereford/Angus crossbred co w/calf pairs were allowed to graze on separate but equivalent pastures , Each year, the cattle from two groups received fenbendazole at the s tart of the study (early May) and then again approximately 6 weeks lat er (mid-June). Weight gain of calves and reproductive efficiency of co ws were measured in both years. Worm burdens were determined during ne cropsy of five nontreated calves at the end of the second year. During the second year, a 39-lb (P < .05) average gain in 205-day weaning we ight was realized. Necropsy-after the second year showed an average Wo rm burden of 5808 worms, consisting mainly of Ostertagia, Cooperia, an d Nematodirus. The worms were primarily responsible for the decreased weight of control animals. The average feed cost to overcome this leve l af parasitism is approximately $.50 per calf per day.