INFLUENCE OF TEMPERING ON THE FEEDING VALUE OF ROLLED CORN IN FINISHING DIETS FOR FEEDLOT CATTLE

Crossbred yearling steers (n = 125; 372 kg) were used in a 109-d finis hing trial. Steers were fed an 88% concentrate diet containing 65% cor n (DM basis) as 1) dry rolled corn (DRC); 2) tempered rolled corn (TRC ), 43 mg surfactant (SarTemp(R))/kg corn; 3) TRC, 172 mg surfactant/kg corn; 4) TRC, 430 mg surfactant/kg corn; and 5) steam-flaked corn (SF C). Corn moisture was greater (3.5%, P < .01) for TRC than for DRC but less (10%, P < .05) than for SFC. Starch enzymatic reactivity was les s for TRC than for either DRC (18%, P < .05) or SFC (42%, P < .01). Te mpering increased the integrity of rolled corn and reduced the amount of particles less than 2 mm in diameter by 54% (P < .01). Steam flakin g corn increased (P < .01) proportion (78%) of the grain having a part icle size distribution of greater than 8 mm, as compared with TRC (25% ) and DRC (3%). Compared with DRC, tempering enhanced (P < .10) ADG (9 %), feed efficiency (5%), and dietary NE (3%). Daily weight gain was s imilar (P > .10) for TRC and SFC. Feed efficiency(P < .10) and dietary NE (P < .01) were greater (6%) for SFC than for TRC. There were no di fferences (P > .10) between DRC and TRC in ruminal and total tract dig estion of OM, N, and starch, and in ruminal microbial efficiency. Rumi nal digestion of OM decreased (linear effect, P < .05) and ruminal mic robial efficiency increased (linear effect, P < .05) with increasing s urfactant concentration. Ruminal digestion of OM and starch, and flow of nonammonia N to the small intestine were greater (31, 56, and 14%, respectively, P < .01) for SFC than for TRC. Postruminal and total tra ct digestion of OM, N, and starch, and dietary DE were greater (P < .0 1) for SFC than for TRC. We concluded that tempering corn will enhance animal performance. Increasing the concentration of surfactant used i n tempering may enhance ruminal microbial efficiency and lean tissue g rowth.