Effects of programming intake on performance and carcass characteristics of feedlot cattle

We conducted two experiments to determine the effects of various intake restriction strategies on performance and carcass characteristics of feedlot cattle. In Exp. 1, 104 steer calves (273 +/- 12 kg BW) were allotted to 12 pens. During Period 1 (273 to 312 kg BW), steers were limit-fed according to net energy equations to achieve predicted gains of .91, 1.13, or 1.36 kg/d. Control steers were offered ad libitum access to feed during this period. During Period 2 (372 to 535 kg BW), all steers were offered ad libitum access to feed. In Period 1, steers limit-fed for predicted gains of .91, 1.13, and 1.36 kg/d gained 1.03, 1.22, and 1.40 kg/d, respectively. Control steers offered ad libitum access to feed gained 1.66 kg/d. Steers that were limit-fed in Period 1 were able to compensate in Period 2; for the total experiment, there were no differences (P > .10) among the four feeding strategies investigated for rate of gain, feed efficiency, total feed intake, and carcass characteristics. Experiment 2 used 107 steer calves (300 +/- 11 kg BW). Four feeding strategies were compared: step-wise increases in intake to program for increasing rate of gain, stepwise decreases in intake to program for decreasing rate of gain, feeding to hold gain constant at 1.36 kg/d, or offering steers ad libitum access to feed throughout the experiment to allow for maximum gains. When averaged over the total experiment, growth rate and days on feed were not affected (P > .10) by feeding system. Steers fed to achieve a step-wise increase in growth rate throughout the experiment had the lowest (P < .09) daily intakes and the highest (P < .09) feed efficiencies. Steers fed for increasing gains required 109 kg/steer less (P < .09) total feed to reach market weight than those offered ad libitum access to feed throughout the experiment. Feeding strategy had little effect on carcass characteristics. We concluded that as intake is restricted to a greater extent, net energy equations are less accurate in predicting rate of gain. Programming intake during the feeding period can result in significant reductions in feed expenditures.