Evaluating Use of Urinary Purine Derivative to Creatinine Ratio as an Estimate of Microbial Protein Production in Steers

Authors

Grant Crawford, University of Nebraska-Lincoln
Matt K. Luebbe, University of Nebraska - LincolnFollow
Galen E. Erickson, University of Nebraska-LincolnFollow
Terry J. Klopfenstein, University of Nebraska-LincolnFollow

Date of this Version

January 2007

Comments

Published in 2007 Nebraska Beef Cattle Report. Copyright © 2006 The Board of Regents of the University of Nebraska.

Abstract

Six ruminally and duodenally fistulated steers were fed three diets varying in source and concentration of dietary protein to determine impacts on ruminal metabolism, nutrient digestibility, and microbial crude protein (MCP) production as estimated by urinary purine derivative:creatinine (PD:C) ratio. Steers were fed a steam-flaked corn (SFC)-based diet with or without 1.5% urea, or a corn milling byproduct-based diet. Feeding a corn milling by-product-based diet resulted in greater ruminal pH and less time below ruminal pH 5.6, total tract OM digestibility, and ruminal propionate concentration when compared with either SFC-based treatment. The by-product-based treatment produced greater PD:C and MCP production values when compared with the SFC, no urea treatment. Responses in ruminal pH, MCP production, and PD:C indicate the by-product-based diet provided a more favorable rumen environment compared with SFC-based diets, and that urinary PD:C can be used to estimate differences in MCP production.