Loerch S C, Fluharty F L
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691-4096, USA.
J Anim Sci. 1998 Feb;76(2):371-7. doi: 10.2527/1998.762371x.
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 372 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.
我们进行了两项试验，以确定不同采食量限制策略对育肥牛生产性能和胴体特性的影响。在试验1中，104头阉牛犊牛（体重273±12千克）被分配到12个围栏中。在第1阶段（体重273至372千克），根据净能方程对阉牛进行限量饲喂，以达到预测日增重0.91、1.13或1.36千克。在此期间，对照阉牛可自由采食。在第2阶段（体重372至535千克），所有阉牛均可自由采食。在第1阶段，限量饲喂以达到预测日增重0.91、1.13和1.36千克的阉牛，日增重分别为1.03、1.22和1.40千克。自由采食的对照阉牛日增重为1.66千克。在第1阶段进行限量饲喂的阉牛在第2阶段能够补偿生长；对于整个试验，在增重速度、饲料效率、总采食量和胴体特性方面，所研究的四种饲喂策略之间没有差异（P>.10）。试验2使用了107头阉牛犊牛（体重300±11千克）。比较了四种饲喂策略：采食量逐步增加以适应增重速度增加的计划，采食量逐步减少以适应增重速度降低的计划，饲喂以使日增重维持在1.36千克不变，或在整个试验期间让阉牛自由采食以实现最大增重。在整个试验中进行平均时，饲喂系统对生长速度和饲养天数没有影响（P>.10）。在整个试验中饲喂以实现生长速度逐步增加的阉牛，日采食量最低（P<.09），饲料效率最高（P<.09）。与在整个试验期间自由采食的阉牛相比，为增加增重而饲喂的阉牛达到上市体重所需的总饲料量少109千克/头（P<.09）。饲喂策略对胴体特性影响很小。我们得出结论，随着采食量限制程度的增加，净能方程在预测增重速度方面的准确性降低。在饲喂期规划采食量可显著降低饲料成本。
