Utilization of White Locoweed (Oxytropis sericea Nutt.) by Range Cattle

Abstract

Utilization studies conducted on a high mountain range determined the quantity and timing of white locoweed (Oxytropis sericea Nutt.) consumption by cattle. Paired plots (one caged and one grazed) were clipped at the end of the grazing season to determine seasonal utilization. Biweekly visual appraisals were used to estimate percentage leaf grazed and number of reproductive stalks grazed and thus determine utilization patterns as the season progressed. Loco comprised 26% of the standing crop. Thirty-four percent of the available loco was utilized during the grazing season. Loco flower and pods (heads) were preferred to leaves. Utilization of loco heads increased linearly as the season progressed. Loco leaves were not consumed until the last 3 weeks of the grazing season. Loco heads also contained the highest concentration of the toxic alkaloid, swainsonine.