Baldwin J K, Griminger P
Exp Gerontol. 1985;20(1):29-34. doi: 10.1016/0531-5565(85)90006-3.
Nitrogen balance studies were conducted to compare the protein requirements of aged (24-month-old) and mature (12-month-old) rats for possible age-related differences. Four diets with protein supplied as amino acid mixtures simulating casein protein at 4.5%, 4.5% plus 1.5% indispensable amino acids of casein, 4.5% plus 1.5% dispensable amino acids of casein or 6.0% casein protein were offered for one week each during a four-week counter-balanced dietary sequence. Lower food and nitrogen intake of aged rats resulted in a lower mean nitrogen balance compared to that of the mature animals. Calculations of the level of N intake necessary to provide for N equilibrium in the aged rats indicated an apparent increase in the actual net need for nitrogen and indispensable amino acids when compared with the needs of the mature animals.
进行了氮平衡研究，以比较老年（24个月大）和成熟（12个月大）大鼠的蛋白质需求，探究可能存在的与年龄相关的差异。提供四种日粮，蛋白质以氨基酸混合物形式供应，分别模拟4.5%的酪蛋白、4.5%的酪蛋白加1.5%的酪蛋白必需氨基酸、4.5%的酪蛋白加1.5%的酪蛋白非必需氨基酸或6.0%的酪蛋白，在为期四周的平衡日粮序列中，每种日粮各提供一周。与成熟动物相比，老年大鼠较低的食物和氮摄入量导致平均氮平衡较低。对老年大鼠达到氮平衡所需的氮摄入量水平的计算表明，与成熟动物的需求相比，其对氮和必需氨基酸的实际净需求明显增加。
