EFFECTS OF PROGRAMMED GAIN STRATEGIES ON PERFORMANCE AND CARCASS CHARACTERISTICS OF STEERS

In Trial 1, 161 Angus x Simmental crossbred steers (initial BW 305 +/- 1.0 kg) were used in a completely randomized design experiment to det ermine the effects of intake restriction and programmed gain on cattle performance and carcass composition and characteristics. Five feeding systems were tested using step-wise increases in programmed intake le vel. Initially steers were fed to gain 1.13 kg/d. Intake was then incr eased to achieve a gain of 1.36 kg/d. At the end of the feeding period , steers had ad libitum access to feed. Duration of intake restriction and the period of unrestricted intake was varied. Feeding steers at r estricted intakes and then increasing daily gain by increasing feed in take using four different schedules all reduced (P <.05) daily feed in take and total feed intake compared with providing ad libitum access t o feed throughout the trial. Furthermore, daily feed efficiency was in creased (P < .05) by two of the feeding systems compared with offering ad libitum access to feed throughout the trial. The feeding system us ed did not affect (P >.10) quality grade of the carcasses. In Trial 2, 77 individually penned Angus x Simmental crossbred steers (initial BW 273 +/- 1.2 kg) were used to determine the effects of various feed in take restriction systems. For systems 1 through 4, multiple periods of restriction and realimentation were investigated; the duration and ma gnitude of restriction were varied. Feed intake was not restricted for steers in system 5. The feed restriction systems used in this experim ent did not result in decreased total feed intake or changes in carcas s composition as compared with offering ad libitum access to feed. Red ucing total energy intake seems to be a prerequisite to altering feed efficiency of steers in limit-feeding systems.