Fistula Sample Numbers Required to Determine Cattle Diets on Forest and Grassland Ranges

Abstract

The variation among esophageal fistulated (EF) cattle in diet nutritive content and botanical composition selection was evaluated on forest and grassland range in the Blue Mountains of eastern Oregon during the summer of 1976. Botanical composition of diet samples was determined with microhistological analysis. Nutritive value was evaluated by analyses for crude protein, acid detergent fiber, permanganate lignin, and in vitro organic matter digestibility. Four collections were made from 4 EF heifers during each of 4 28-day periods on each vegetation type. Collections were alternated between morning and afternoon on each vegetation type. EF cattle selected diets of different (P<.05) botanical composition and nutritive quality in the early morning compared with the late afternoon. They grazed open grassland areas in the morning and shaded areas in the afternoon. Several more EF cattle and collections were required to determine diet botanical composition than nutritive quality on both the forest and grassland. A minimum of 4 EF cattle and 4 collections were needed to adequately sample diet nutritive characteristics on the grassland and forest pastures. The data indicated collections should be rotated between morning and afternoon on ranges supporting a mosaic of grassland and forest plant communities.