Effects of Concentration and Source of Supplemental Fat and Protein on Performance of Newly Arrived Feedlot Steers

Three experiments were conducted to determine the effects of supplemental fat and CP concentration in diets of newly received steers. In Exp. 1, 72 steers (initial BW 201 ± 17 kg) were used in a 2 × 2 × 2 factorial experiment to determine effects of fat (Megalac, a calcium soap of palm fatty acids [CS]) concentration (0 vs 2%), CP concentration (12 vs 14%), and CP source (spray-dried blood meal [BM] vs soybean meal [SBM]) in receiving diets. Steers fed BM ate 22.8% more during wk 1 and 15.0% more during wk 2 if there was no CS in their diets compared with steers fed BM plus 2% CS (P < .05). In Exp. 2, 160 steers (initial BW 247 ± 16 kg) were used in a randomized complete block design experiment to determine effects of adding CS (0, 2, or 4%) to 14% CP diets containing BM. No differences (P > .10) in ADG or feed efficiency (FE) occurred due to CS. In Exp. 3, 186 steers (initial BW 243 ± 20 kg) were used in a randomized complete block design experiment to determine effects of supplemental fat source in receiving diets on steer performance. Diets contained either 0% added fat (control), 4% CS, or 4% animal-vegetable blend (AV). Feeding AV improved ( P < .05) ADG and FE during wk 2 and FE for the total trial. Addition of AV to high-protein (15 to 22% CP) receiving diets improved FE, and CS resulted in no improvements in performance.