Canolty N L
Department of Foods and Nutrition, University of Georgia, Athens 30602.
Prog Food Nutr Sci. 1988;12(3):293-6.
Diets were formulated to contain varying concentrations of lactalbumin (3, 6, 9, 12, 15 and 18%), with lactalbumin increased at the expense of the carbohydrate source (Formulation 1) or with the nonprotein composition held constant (Formulation 2). Diets were fed for 21 days to male weanling rats of the Sprague-Dawley strain at three levels of intake (7, 9 or 11 g/day). For each diet formulation, maximum body weight gain (Rmax) was predicted for each intake level by relating body weight gain and protein intake using the saturation kinetics model. Rmax and asymptotic standard errors at intake levels 1, 2 and 3 were 10 +/- 3, 50 +/- 16 and 80 +/- 12 g, respectively, for Formulation 1, and 12 +/- 3, 40 +/- 3 and 69 +/- 4 g, respectively, for Formulation 2. Combining diet formulations, Rmax expressed as percentages of Rmax at intake level 3 were approximately 15 and 60% at intake levels 1 and 2, respectively. Since intakes at levels 1 and 2 were approximately 64 and 82%, respectively, of that at level 3, the results of this study show that the percentage decrease in Rmax is much greater than the percentage decrease in intake. This study has demonstrated that saturation kinetics can be used to model the effects of energy restriction on protein utilization.
所配制的日粮含有不同浓度的乳白蛋白（3%、6%、9%、12%、15%和18%），其中乳白蛋白的增加是以碳水化合物来源为代价（配方1），或者非蛋白质成分保持不变（配方2）。将这些日粮以三种摄入量水平（7、9或11克/天）喂给斯普拉格-道利品系的雄性断奶大鼠21天。对于每种日粮配方，通过使用饱和动力学模型将体重增加与蛋白质摄入量相关联，预测了每个摄入量水平下的最大体重增加量（Rmax）。对于配方1，摄入量水平1、2和3时的Rmax和渐近标准误差分别为10±3、50±16和80±12克；对于配方2，分别为12±3、40±3和69±4克。综合日粮配方来看，以摄入量水平3时的Rmax的百分比表示，摄入量水平1和2时的Rmax分别约为15%和60%。由于摄入量水平1和2时的摄入量分别约为摄入量水平3时的64%和82%，本研究结果表明，Rmax的下降百分比远大于摄入量的下降百分比。本研究表明，饱和动力学可用于模拟能量限制对蛋白质利用的影响。
