Botanical Composition and Diet Quality of Cattle Under a Short Duration Grazing System

Abstract

A study was conducted in 1981 and 1982 at the Dickinson Experiment Station Ranch Headquarters in the mixed grass prairie of western North Dakota to determine seasonal and daily cattle diets under a short duration grazing system. Significant seasonal decreases in crude protein (CP) and in vitro digestible organic matter (IVDOM) were determined both years of the study. Dietary CP did not meet lactating and/or dry, pregnant cow requirements throughout the grazing season either year. In 1981, no seasonal difference in dietary CP and IVDOM was determined between the initiation and termination of grazing on individual paddocks. Only one significant difference occurred in 1982 when dietary CP decreased significantly between the first and last day of grazing individual paddocks in fall. Grass dominated cattle diets both years of the study. The major grasses selected were western wheatgrass (Agropyron smithii), needle-and-thread (Stipa comata), and blue grama (Bouteloua gracilis). Cattle showed no consistent seasonal trend in grass or browse selection, while forbs decreased in diets as the grazing season advanced. Selection of forage species and plant classes by cattle while they occupied a paddock varied little during seasonal collection periods throughout the study.