Leeson S, Caston L, Summers J D
Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
Poult Sci. 1996 Apr;75(4):529-35. doi: 10.3382/ps.0750529.
Male broiler chickens were fed corn-soybean diets providing 2,700, 2,900, 3,100 or 3,300 kcal ME/kg. In all experiments, each treatment was tested with three replicate groups of 30 birds grown to 49 d of age. In Experiment 1, birds consumed the various diets ad libitum whereas in Experiment 2, all birds received identical and restricted quantities of feed so as to ensure variable intakes of energy. In a third experiment, after 7 d of age, broilers had access to feed in two feeders that contained only the highest level of energy, or the 3,300 kcal ME/kg diet in combination with one of the other diets previously described. Providing diets of 2,700 to 3,300 kcal ME/kg for ad libitum consumption had no effect on growth rate (P > 0.05) and energy intake was constant; however, reducing the energy level of the diet did result in reduced carcass fatness (P < 0.01). When feed intake was controlled in Experiment 2, there was reduced growth (P < 0.01) rate as energy level of the diet was reduced. This reduced growth was associated with dramatic reduction in carcass fatness (P < 0.01), although breast meat yield was not affected. When broilers were offered a choice of diets, they showed remarkably precise control of intake, such that energy intake was again constant across all treatments. However, even though energy intake was constant, broilers consuming the choice diets involving the lower energy content diets tended to have less carcass fat. It is concluded that the broiler still possesses a good ability to control its feed intake based on desire to normalize energy intake. As energy intake is decreased, or there is increased protein intake, the bird deposits less carcass fat.
雄性肉鸡被饲喂代谢能分别为2700、2900、3100或3300千卡/千克的玉米-大豆日粮。在所有实验中，每个处理均用三组、每组30只鸡进行测试，饲养至49日龄。在实验1中，鸡自由采食各种日粮，而在实验2中，所有鸡均接受相同且限量的饲料，以确保能量摄入量不同。在第三个实验中，7日龄后，肉鸡可以在两个料槽中采食，一个料槽仅装有能量水平最高的日粮，即3300千卡代谢能/千克的日粮，另一个料槽装有上述其他日粮之一与该日粮的组合。提供2700至3300千卡代谢能/千克的日粮供自由采食对生长速度没有影响（P>0.05），能量摄入量保持恒定；然而，降低日粮的能量水平确实会导致胴体脂肪含量降低（P<0.01）。在实验2中控制采食量时，随着日粮能量水平的降低，生长速度下降（P<0.01）。这种生长速度的下降与胴体脂肪含量的显著降低有关（P<0.01），尽管胸肉产量不受影响。当给肉鸡提供日粮选择时，它们对采食量表现出非常精确的控制，以至于所有处理的能量摄入量再次保持恒定。然而，尽管能量摄入量恒定，但采食含有较低能量日粮组合的肉鸡胴体脂肪往往较少。结论是，肉鸡仍然具有基于使能量摄入正常化的欲望来很好地控制其采食量的能力。随着能量摄入量的减少或蛋白质摄入量的增加，鸡沉积的胴体脂肪减少。
