Effects of dietary energy source and level on performance of newly arrived feedlot calves.

Three experiments were conducted with Simmental x Angus crossbred steers to determine the effects of energy source and level on performance of newly arrived feedlot calves. In trial 1, 68 steers (initial BW 215 +/- 9.4 kg) were used in a 2 x 3 factorial experiment to determine the effects of receiving diet and previous creep feed on performance. Diets were composed primarily of either corn silage, corn silage + alfalfa pellets + dry corn, or dry corn + alfalfa pellets. For the 41-d trial, calves fed the corn silage-based diet had greater (P < .05) ADG and feed efficiencies than calves fed the other two diets. In Trial 2, 60 steers (initial BW 212 +/- 4.6 kg) were used in a 28-d completely randomized design experiment to determine the effects of 16% CP receiving diets containing 70, 75, 80 or 85% concentrate on performance. There were no differences (P > .10) in ADG or feed efficiency due to dietary concentrate level. In Trial 3, 77 steers (initial BW 226.3 +/- 3.0 kg) were used in a 2 x 3 factorial experiment to determine the effects of dietary concentrate and protein levels on performance during a 28-d receiving period. The factors were concentrate level (70 vs 85% concentrate) and protein level (12.5%, 16%, or phase-fed at 23%, 17%, 14%, and 12.5% during wk 1, 2, 3, and 4, respectively). During wk 1, calves fed the 85% concentrate diet had greater (P < .01) DMI, ADG, and feed efficiency compared with 70% concentrate. Calves fed the 16% CP and phase-fed protein diets had greater (P < .01) DMI, ADG, and greater (P < .02) feed efficiency than calves fed the 12.5% CP diets. Receiving diets containing at least 16% CP and > 70% concentrates are beneficial to calves during the first week after feedlot arrival.