Kishi K, Rikimaru K, Matsumoto Y, Shizuka F, Inoue G
Jpn J Physiol. 1982;32(6):959-70. doi: 10.2170/jjphysiol.32.959.
Voluntary intake of proteins of various qualities in relation to dietary protein utilization was investigated in growing and adult rats. The rats were given two diets, one containing high protein and the other no protein, and were allowed to self-select protein and energy intakes freely from both diets. The results showed that total food intake (protein diet plus protein-free diet) and body weight gain were similar among five proteins tested. However, the amount of protein consumed by the growing rats per 100 g of total food intake (i.e., dietary protein level) was different depending upon the protein qualities, that is, wheat gluten (WG) 44 g, casein (CA) 30 g, soy protein (SP) 21 g, lactalbumin (LA) 19 g, and amino acid mixture simulating egg protein (AA) 11 g. Net protein utilization (NPU), estimated as the proportion of protein intake that is retained in the body, was as follows: WG, 20%; CA, 33%; SP, 44%; LA, 50%; and AA, 74%. From the above figures, net dietary protein value, which is a measure of utilizable protein in the diet, was calculated by multiplying the dietary protein level by NPU. In contrast to the difference in protein intake, net dietary protein value was quite constant in spite of large differences in the dietary protein quality, being 8 to 10%. A similar relationship between protein intake and protein utilization was obtained also with adult rats, except that the net dietary protein value was smaller in adult rats than in growing rats. These results may suggest that the animals can regulate the intake of dietary protein to keep the amount of protein available for the body constant.
研究了生长大鼠和成年大鼠对不同质量蛋白质的自愿摄入与膳食蛋白质利用率之间的关系。给大鼠提供两种日粮，一种含高蛋白，另一种不含蛋白质，让它们从两种日粮中自由选择蛋白质和能量摄入量。结果表明，在测试的五种蛋白质中，总食物摄入量（蛋白质日粮加无蛋白质日粮）和体重增加相似。然而，生长大鼠每100克总食物摄入量所消耗的蛋白质量（即膳食蛋白质水平）因蛋白质质量而异，即小麦面筋（WG）44克、酪蛋白（CA）30克、大豆蛋白（SP）21克、乳白蛋白（LA）19克和模拟鸡蛋蛋白的氨基酸混合物（AA）11克。净蛋白质利用率（NPU），以保留在体内的蛋白质摄入量的比例来估计，如下所示：WG为20%；CA为33%；SP为44%；LA为50%；AA为74%。根据上述数据，通过将膳食蛋白质水平乘以NPU来计算膳食净蛋白质值，这是衡量日粮中可利用蛋白质的指标。与蛋白质摄入量的差异相反，尽管膳食蛋白质质量差异很大，但膳食净蛋白质值相当恒定，为8%至10%。成年大鼠也获得了类似的蛋白质摄入量与蛋白质利用率之间的关系，只是成年大鼠的膳食净蛋白质值比生长大鼠小。这些结果可能表明，动物可以调节膳食蛋白质的摄入量，以使可供身体利用的蛋白质量保持恒定。
