EFFECTS OF PROGRAMMING INTAKE ON PERFORMANCE AND CARCASS CHARACTERISTICS OF FEEDLOT CATTLE

We conducted two experiments to determine the effects of various intak e restriction strategies on performance and carcass characteristics of feedlot cattle. In Exp. 1, 104 steer calves (273 +/- 12 kg BW) were a llotted to 12 pens. During Period 1 (273 to 312 kg BW), steers were li mit-fed according to net energy equations to achieve predicted gains o f .91, 1.13, or 1.36 kg/d. Control steers were offered ad libitum acce ss 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 li mit-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 ac cess 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 w ere no differences (P > .10) among the four feeding strategies investi gated for rate of gain, feed efficiency, total feed intake, and carcas s characteristics. Experiment 2 used 107 steer calves (300 +/- 11 kg B W). Four feeding strategies were compared: step-wise increases in inta ke to program for increasing rate of gain, stepwise decreases in intak e to program for decreasing rate of gain, feeding to hold gain constan t at 1.36 kg/d, or offering steers ad libitum access to feed throughou t the experiment to allow for maximum gains. When averaged over the to tal experiment, growth rate and days on feed were not affected (P > .1 0) by feeding system. Steers fed to achieve a step-wise increase in gr owth rate throughout the experiment had the lowest (P < .09) daily int akes and the highest (P < .09) feed efficiencies. Steers fed for incre asing gains required 109 kg/steer less (P < .09) total feed to reach m arket weight than those offered ad libitum access to feed throughout t he experiment. Feeding strategy had little effect on carcass character istics. We concluded that as intake is restricted to a greater extent, net energy equations are less accurate in predicting rate of gain. Pr ogramming intake during the feeding period can result in significant r eductions in feed expenditures.