PERFORMANCE, DIGESTION, AND MASTICATION EFFICIENCY OF HOLSTEIN STEERSFED WHOLE OR PROCESSED CORN IN LIMIT-FED OR FULL-FED GROWING-FINISHING SYSTEMS

We conducted two trials to examine the effects of restricted vs full f eeding and of grain processing method on feedlot performance, digestio n, and mastication efficiency by Holstein steers in different growing- finishing systems. In Trial 1, 272 Holstein steers (177 +/- 9.98 kg) w ere blocked by weight and assigned to growing phase diets based on cor n silage (SIL), steam-flaked corn that was either limit-fed (SFLF) or full-fed (SFFF), or whole corn that was limit-fed (WCLF) or full-fed ( WCFF). Limit-fed steers were fed at levels predicted to allow daily ga in of 1 kg/d. On d 112, all steers were switched to WCFF or SFFF diets until the mean BW of each treatment group was 545 kg. Overall, steers fed WOLF and SFLF during the growing phase and finished on SF were 8. 1 and 6.6% more efficient at converting dietary ME to gain (P = .02 an d .04, respectively) than steers in the SFFF group. In Trial 2, three ruminally and duodenally cannulated Holstein steers were fed whole (WC ) and rolled corn (RC) diets at FF and LF intake in an incomplete repl icated 2 x 2 switchback design. Ad libitum access to feed resulted in higher(P =.02) ruminal starch digestibility than did limit-feeding, an d calves had higher total tract DM (P = .05) and starch (P = .03) dige stion at the heavier BW. Limit-feeding whole corn resulted in increase d particle size of masticate (P = .06) compared with full-feeding whol e corn. Because of apparent differences in mastication efficiency betw een limit-fed and full-fed calves, grain processing method during peri ods of restriction and compensatory growth may be important considerat ions for managing growth in systems that incorporate limit-feeding.