Miyatani S, Kishi K, Takahashi K, Zushi F
J Nutr Sci Vitaminol (Tokyo). 1977;23(5):455-66. doi: 10.3177/jnsv.23.455.
The nutritive values of proteins in relation to their intake levels were evaluated by feeding adult male rats weighing 250 g diets containing 0%, 0.39%, 0.78%, 1.56%, 2.34%, 3.90%, 7.79% and 15.58% lactalbumin or wheat gluten for three weeks. The biological values (BV) of both proteins were high at low levels of protein intake but decreased with increase in protein intake. The BV of wheat gluten was estimated to be about 100 at a level of intake of 1.56% but only 25 at a level of 15.58%. Similarly, the BV of lactalbumin decreased with increase in the protein level, being 67 at a level of 7.79%. The BVs of both proteins at low levels of dietary protein (below 2.34% of lactalbumin or 0.78% of wheat gluten) were apparently more than 100 because urinary N excretion was less than endogenous N. The BVs also decreased with time during the three-week test period. It is concluded that BV of a protein is not a fixed value but varies with the experimental conditions especially with changes in the amount of intake, and that differences in the qualities of various proteins cannot be compared quantitatively at a single level of protein. The results were briefly discussed in relation to protein requirements.
通过给体重250克的成年雄性大鼠喂食含0%、0.39%、0.78%、1.56%、2.34%、3.90%、7.79%和15.58%乳白蛋白或小麦麸质的日粮三周，评估了蛋白质的营养价值与其摄入量的关系。两种蛋白质的生物利用率（BV）在低蛋白质摄入量时较高，但随蛋白质摄入量的增加而降低。小麦麸质的BV在摄入量为1.56%时估计约为100，但在摄入量为15.58%时仅为25。同样，乳白蛋白的BV也随蛋白质水平的增加而降低，在7.79%的水平时为67。在低日粮蛋白质水平（低于2.34%的乳白蛋白或0.78%的小麦麸质）时，两种蛋白质的BV明显超过100，因为尿氮排泄量低于内源氮。在为期三周的测试期内，BV也随时间降低。得出的结论是，一种蛋白质的BV不是一个固定值，而是随实验条件变化，尤其是随摄入量的变化而变化，并且不能在单一蛋白质水平上对各种蛋白质质量的差异进行定量比较。结合蛋白质需求对结果进行了简要讨论。
