EFFECTS OF DIETARY ENERGY-SOURCE AND LEVEL ON PERFORMANCE OF NEWLY ARRIVED FEEDLOT CALVES

Three experiments were conducted with Simmental x Angus crossbred stee rs 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 th e effects of receiving diet and previous creep feed on performance. Di ets were composed primarily of either corn silage, corn silage + alfal fa pellets + dry corn, or dry corn + alfalfa pellets. For the 41-d tri al, calves fed the corn silage-based diet had greater (P < .05) ADG an d feed efficiencies than calves fed the other two diets. In Trial 2, 6 0 steers (initial BW 212 +/- 4.6 kg) were used in a 28-d completely ra ndomized design experiment to determine the effects of 16% CP receivin g diets containing 70, 75, 80, or 85% concentrate on performance. Ther e were no differences (P > .10) in ADG or feed efficiency due to dieta ry 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% conc entrate) 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, calve s fed the 85% concentrate diet had greater (P < .01) DMI, ADG, and fee d 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.