steers, feedlot, protein
Feedlot cattle are now capable of growth rates that greatly exceed our descriptions for established nutrient requirements. We must now redefined the impact of sources and levels of dietary CP on growth rate and efficiency. Pursuing this question, yearling steers (n = 360 x BW = 790 ± 10) were fed various levels and sources of supplement crude protein during a 120 day finishing period. Diets were formulated to contain 12 or 13% CP. Supplemental CP was provided in the forms of urea, soybean meal, bloodmeal, and feather meal. Actual dietary CP levels of 1 1.8% and 12.6% were lower than formulations but still allowed for level comparisons. Higher CP levels improved feed/gain (PC .05) during the initial 42 days on feed in only one set of diet contrasts. CP level did not affect cumulative performance by steers. In one set of contrasts SBM supported higher (P<.05) ADG and a trend (P<.15) toward improved feed/gain over urea based supplements. In a second set of contrasts SBM tended to support higher ADG (PC.15) and higher DM1 (P<.10) than urea plus escape protein liquid supplements. There were no interactions between sources and levels of supplemental CP. The apparent CP requirement of medium framed steers gaining over 4 Ib per day was not greater than 11.8% of the diet.
Number of Pages
South Dakota State University
Copyright © 1995 South Dakota State University.
Pritchard, R. H., "Evaluation of Crude Protein Sources and levels for High Growth Potential Yearling Steers Fed High Energy Diets" (1995). South Dakota Beef Report, 1995. 10.