Prior grazing by sheep reduces waxy larkspur consumption by cattle: An observation

Abstract

Sheep are more resistent to larkspur poisoning than cattle. Grazing larkspur with sheep before cattle turn-in may reduce the threat of cattle poisoning. Two 2.1-ha pastures were established in Upper Ruby Valley in southwest Montana in 1987 and 1989. A band of sheep grazed 1 pasture in mid-June in both years. Sheep grazed 70% of larkspur stalks in 1987 and 35% in 1988. Because sheep grazed little larkspur in 1988, larkspur was hand decapitated to simulate the use obtained in 1987 for the subsequent cattle grazing portion of the trial. Five cows were placed in each pasture immediately following sheep grazing in 1987 and after a 3-week delay in 1998. Cattle diets were quantified by bite counts. Waxy larkspur consumption by cattle in the sheep-grazed pasture was lower than in the cattle-only pasture especially during and after rainstorms in 1987 and throughout the study in 1988. One cow died from larkspur poisoning in the cattle-only pasture in 1988. If sheep will graze waxy larkspur, subsequent consumption by cattle can apparently be reduced on this site, thus reducing the risk of poisoning.