Effects of Horn Fly (Diptera: Muscidae) Control on Cows and Gastrointestinal Worm (Nematode: Trichostrongylidae) Treatment for Calves on Cow and Calf Weight Gains

Abstract

Horn flies, Haematobia irritans (L.), at an average population level of 197 per cow, did not significantly affect cow, calf, or cow/calf seasonal weight gains during a 3-yr study in the central sandhills of Nebraska. Cattle aggregation was not influenced by horn fly population levels encountered in this study. Treatment of calves with a anhelmintic drug (thiabendazole) increased calf weight gains significantly despite a helminthic infection without clinical symptoms.