Supplement and Forage Effects on Fecal Output Estimates from an Intra-Ruminal Marker Device

Abstract

Three experiments were conducted to evaluate effects of supplemental protein and forage on marker estimated fecal output using an intraruminal continuous release marker device in grazing steers. In experiment 1, twelve steers were assigned to 3 treatments and fecal collections were made during a 6-day period in December 1990 and again in February 1991. Treatments were: 1) range forage only, 2) range forage + 0.32 kg protein/day from a 70% soybean meal - 30% wheat pellet, and 3) range forage + 0.32 kg crude protein/day from 15.1% meadow hay. Fecal output estimates derived from the marker device were similar (P > 0.10) for all treatments and both periods. Fecal estimates derived from the marker device were greater (P 0.10) for the 2 supplement treatments. Fecal output estimates were greater (P 0.10; r = 0.93) on range in September. Protein supplements had no effect on fecal estimates derived from chromic oxide released from a marker device, but the marker estimates were affected by forage source. Correlation between fecal collection and the marker method is high; however, total fecal collection should be used to correct fecal output derived by the marker device for each forage source.