ABSTRACT

1. Two experiments were carried out to investigate the influence of substitution levels, assay methods and adaptation length of broilers to experimental diets on metabolisable energy of corn and barley (Experiment 1) and soya bean meal (Experiment 2). In each experiment, the test feedstuffs proportionately replaced the reference diet at the rates of 150, 300 or 450 g/kg. Each treatment had 8 or 7 replicate cages containing three birds per cage. Broiler chickens were adapted to experimental diets for either 7 or 4 d prior to excreta collection on d 20 and 21.

2. Metabolisable energy was determined using the difference method at each substitution level and the regression method, using the 4 combinations of the substitution levels.

3. In Experiment 1, AME and AMEn were lower (P < 0.01) for barley than for maize, irrespective of the assay method and there was a trend for an adaptation × cereal grains interaction (P < 0.10) for AME determined by the difference regression method. For maize, AME and AMEn calculated using regression or the difference method were not significantly different, whereas barley AME and AMEn values were greater (P < 0.01) when derived using regression analysis.

4. In Experiment 2, there was no significant adaptation length × substitution levels interaction. The AME and AMEn values were lowest (P < 0.01) at 150 g/kg SBM inclusion level when calculated using the difference method. On the other hand, AME and AMEn values determined by the regression method were not influenced by substitution levels.

5. It was concluded that the influence of substitution levels on assayed metabolisable energy is feedstuff-dependent and that the regression method produced more consistent metabolisable energy values in a feedstuff-independent manner.

抽象的

1.进行了两个实验，研究了替代水平，测定方法和肉鸡对实验日粮的适应长度对玉米和大麦（实验1）和豆粕（实验2）的代谢能的影响。在每个实验中，测试饲料均以150、300或450 g / kg的比例成比例地代替了参考日粮。每个处理有8或7个重复的笼子，每个笼子中有三只鸟。在第20和21天收集粪便之前，将肉鸡适应实验饮食7或4 d。

2.使用取代水平的4种组合，使用每个取代水平的差异方法和回归方法确定可代谢能量。

3.在实验1中，大麦的AME和AMEn均低于玉米（P <0.01），而与测定方法无关，并且由差值确定的AME具有适应性×谷粒相互作用（P <0.10）的趋势回归方法。对于玉米，使用回归或差异法计算得出的AME和AMEn差异不显着，而使用回归分析得出的大麦AME和AMEn值较大（P <0.01）。

4.在实验2中，没有显着的适应长度×取代水平相互作用。当使用差异法计算时，在150 g / kg SBM夹杂物含量下，AME和AMEn值最低（P <0.01）。另一方面，通过回归方法确定的AME和AMEn值不受替代水平的影响。

5.结论是，取代水平对测定的可代谢能量的影响取决于饲料，并且回归方法以与饲料无关的方式产生了更一致的可代谢能量值。