Effect of Combinations of Feather Meal, Corn Gluten Meal, Soybean Meal, and Urea as Sources of Supplemental Protein on Nitrogen Balance and Characteristics of Rumen Contents of Cattle

Steers in metabolism stalls and ruminally cannulated steers were used in two separate 8 x 8 Latin Square experiments to evaluate several combinations of protein sources that supplied 33% of the total dietary protein. Protein sources compared were urea (U), hydrolyzed feather meal (HFM), hydrolyzed feather meal plus urea (HFM+U), soy-bean meal (SBM), hydrolyzed feathermeal plus soybean meal (HFM+SBM), corn gluten meal (CGM), corn gluten meal plus urea (CGM+U), and corn gluten meal plus soybean meal (CGM+SBM), with the combinations being a 50:50 CP mixture. There were no differences among protein sources compared in N retention (45.9 ± 5.09 g/d) or N retention as a percentage of N intake 29.8 + 3.24%). Hydrolyzed feather meal N was less (P<.05) digestible (64.0%) than that from U (73.7), HFM+U (68.4), SBM (72.6), HFM+SBM (69.3), CGM (70.0), CGM+U (71.6), or CGM+SBM (72.3). Urea-N digestibility was higher (P<.05) than was HFM+U-N and HFM+SBM-N. Blood urea-N was not affected by protein source at 2 h, but was higher (P<.05) for U at 4 and 6 h vs. other treatments. Ruminal fluid NH3-N and pH were increased (P<.05) by protein source at 2 and 4 h but not at 6 h. Total VFA concentrations were not affected by protein source at 2, 4, and 6 h. Urea or SBM used in combination with CGM or HFM may reduce the cost of protein supplementation without affecting N utilization by steers.