Prediction of optimal rumen degradable protein levels in no-roughage, corn-based feedlot diets

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The need to balance no-roughage, corn-based feedlot diets for rumen degradable protein inclusion is essential in the feedlot setting. Five crossbred steers were fitted with ruminal and duodenal cannulas and used in a 5x5 Latin square design experiment. Dietary treatments were: CON (98% corn; 4.4% RDP), LOW RDP (90.1% corn, 7.9% SBM; 6.6% RDP), MID RDP (82% corn, 16% SBM; 8.8% RDP), HIGH RDP (73.9% corn, 24.1% SBM; 11% RDP), and NPN (96.3% corn, 1.7% biuret; 8.8% RDP). The CON and NPN diets were designed to limit MOEFF. Additionally, 100 crossbred steers were blocked by weight and divided into twenty pens. Dietary treatments were fed for 105 days and were CON (95.55% corn, 4.7% RDP), LOW (93.15% corn, 1.7% SBM, 1.15% urea, 5.2%RDP), MID (90.8% corn, 4.5% SBM, 0.7% urea, 5.9% RDP), HIGH (88.0% corn, 7.8% SBM, 0.2% urea, 6.7% RDP), NPN (94.6% corn, 1.4% urea, 4.7% RDP). The added RDP diets were designed to test that MOEFF, once optimized by RDP level, would not be enhanced by further increasing RDP. The NPN diet was used to compare non-protein to true protein nitrogen. We concluded from these results that RDP-peptide requirement was predictable and that diets can be formulated to meet this requirement.