EFFECT OF DEGRADABLE AND ESCAPE PROTEIN AND ROUGHAGE TYPE ON PERFORMANCE AND CARCASS CHARACTERISTICS OF FINISHING YEARLING STEERS

We evaluated protein sources for finishing steers in two randomized co mplete block design experiments. Experiment 1 used 144 steers (334 kg) with 2 x 3 factorially arranged treatments. Basal diets contained .9% urea or 5.6% soybean meal (SBM) and were either not supplemented or s upplemented with additional protein (2%) fi om blood meal-corn gluten meal (BMCG) or SBM. Steers fed urea-containing diets consumed 4.6% (P < .10) more feed than those fed SBM-supplemented basal diets. On the b asis of carcass weights, steers fed diets containing SBM as the basal protein source were 3.8% (P < .10) more efficient than those fed urea- containing diets; supplying additional SBM improved gain efficiency (G /F) 4.3% (P < .10) compared with BMCG. in Exp. 2, 384 steers (367 kg) were fed diets containing 1.0% urea (DM basis) and 10% roughage as eit her sorghum silage (four diets) or alfalfa hay (two diets). Additional protein was either not provided or provided (2%) as SBM, sunflower me al (SFM), or a 50:50 (N basis) SBM:SFM blend in silage-containing diet s; for diets containing alfalfa, additional protein was either not pro vided or provided (2%) as SBM. Averaged across roughage source, added SBM tended (P = .16) to increase ADG. Dressing percent decreased (P = .09) with added SBM but was higher(P = .04) with alfalfa as roughage s ource. Feeding alfalfa vs sorghum silage as the roughage source increa sed carcass adjusted ADG 4.3% (P = .06) and G/F 4.8% (P = .02). Supple menting high-grain diets with SBM enhanced diet utilization, but BMCG was of little value.