Cattle Grazing White Locoweed: Influence of Grazing Pressure and Palatability Associated with Phenological Growth Stage

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Abstract
Understanding the conditions in which livestock consume poisonous plants is necessary to develop management strategies to reduce losses. Three 10-day grazing trials were conducted to observe consumption of white locoweed (Oxytropis sericea Nutt.) by cattle. The trials corresponded to the phenological growth stages of white locoweed: (1) flower; (2) immature seed pod; and (3) mature seed pod/seed shatter. Six esophageally fistulated Hereford steers were used to collect diet samples. In trial 1, steers selected the locoweed flower only when supplies of grass and other forbs were depleted. In trial 2, steers voluntarily selected the immature pod, which comprised 50% of their diet by the middle of the trial. There was very little consumption of locoweed in trial 3. Few locoweed leaves were consumed throughout the experiment. Immature locoweed pods were palatable and readily selected by cattle. By restricting access at the immature pod growth stage and insuring adequate forage is available at other times, cattle consumption of white locoweed on this site should be minimized.