Department of Agriculture and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
J Anim Physiol Anim Nutr (Berl). 2013 Feb;97(1):197-204. doi: 10.1111/j.1439-0396.2011.01262.x. Epub 2011 Dec 13.
The effects of dietary protein and feeding levels on dietary metabolizable (ME) and net energy (NE) content were determined in 24 pigs, each offered two diets at 2.0 times the energetic maintenance requirement or for ad libitum intake between 55 and 95 kg body weight. Within feeding levels, pigs received, in random order, low-protein (LP; 11.2% CP, 0.61% lysine) or high-protein (HP; 20.2% CP, 0.61% lysine) diets of similar digestible energy content. Dietary NE was calculated from heat production based on 24-h indirect calorimetry following a 7-day N-balance period. Feed intake was greater for LP than HP when fed for ad libitum intake (p = 0.001). Protein level did not affect daily gain (p > 0.1) but HP improved gain: feed (p = 0.003). Dietary ME and NE were not significantly affected by feeding level but were decreased by high protein intake (p < 0.07). Reducing dietary protein reduced urinary energy losses and increased energy retention but did not affect heat production. The effect of dietary protein restriction was already evident on the ME level and carried over to a similar degree to the NE level because the utilization of ME was not affected by protein level. Dietary ME and NE decreased by 0.012 MJ/kg (p = 0.014) and 0.018 MJ/kg (p = 0.062), respectively, for each gram per day N intake. The results suggest that although there was an effect of protein level on NE, the greatest effect occurred at the level of ME. However, the prediction of both ME and NE may be improved by adopting energy values for dietary protein that changes with dietary protein content.
在 24 头猪中，测定了饲粮蛋白质和饲喂水平对饲粮代谢能（ME）和净能（NE）含量的影响。这些猪的体重大约在 55 至 95 千克之间，在 2 倍能量维持需要量的水平下，2 种能量水平各饲喂 12 头猪，或者自由采食。在饲喂水平下，猪随机饲喂低蛋白（LP；11.2%粗蛋白，0.61%赖氨酸）或高蛋白（HP；20.2%粗蛋白，0.61%赖氨酸）饲粮，但这些饲粮的可消化能量含量相似。通过 24 小时间接测热法测定热产生量，计算饲粮 NE，采用 7 天的氮平衡期。LP 组的采食量大于 HP 组（p=0.001）。蛋白质水平对日增重没有影响（p>0.1），但 HP 提高了饲料效率（p=0.003）。饲喂水平对 ME 和 NE 没有显著影响，但高蛋白摄入降低了 ME 和 NE（p<0.07）。降低饲粮蛋白质减少了尿能损失，增加了能量保留，但对热产生没有影响。饲粮蛋白质限制对 ME 水平的影响已经显现，并以类似程度传递到 NE 水平，因为蛋白质水平不影响 ME 的利用率。ME 和 NE 分别降低 0.012 MJ/kg（p=0.014）和 0.018 MJ/kg（p=0.062），饲粮氮摄入量每天增加 1 克。结果表明，尽管蛋白质水平对 NE 有影响，但最大的影响发生在 ME 水平。然而，通过采用随饲粮蛋白质含量变化的饲粮蛋白质能量值，可能会改善 ME 和 NE 的预测。
