Jansen G R, Schibly M B, Masor M, Sampson D A, Longenecker J B
J Nutr. 1986 Mar;116(3):376-87. doi: 10.1093/jn/116.3.376.
Free amino acid levels were determined in serum, mammary gland, liver and muscle during lactation in rats fed diets varying in protein. Using a 3 X 2 factorial design, after conception female rats were fed purified diets varying in protein quality (wheat, wheat + lysine + threonine or casein + methionine) and in protein level (11.6% vs. 22.3%). On d 15 of lactation dams were decapitated; blood was collected, and the serum was quickly frozen. Samples of mammary gland, liver and calf muscle were also removed and quickly frozen. After deproteinization, free amino acids were determined on an LKB 4400 Amino Acid Analyzer. As the protein nutritional value of the diet increased, milk yield increased threefold and the level of free lysine in the mammary gland increased six- to eightfold. With protein quality or quantity improvement, the level of free methionine increased two- to threefold, and no consistent changes were seen in the levels of free threonine, aromatic and branched chain amino acids in mammary glands. Free lysine concentrations in mammary gland, liver and muscle were highly correlated with free lysine in serum (r2 = 0.94, 0.96, 0.93, respectively). Under the conditions of this experiment, a direct relationship between dietary lysine, free lysine in the mammary gland and milk secretion was observed.
在哺乳期，对食用不同蛋白质含量日粮的大鼠的血清、乳腺、肝脏和肌肉中的游离氨基酸水平进行了测定。采用3×2析因设计，受孕后的雌性大鼠被喂食蛋白质质量（小麦、小麦+赖氨酸+苏氨酸或酪蛋白+蛋氨酸）和蛋白质水平（11.6%对22.3%）不同的纯化日粮。在哺乳期第15天，将母鼠断头；采集血液，血清迅速冷冻。同时取出乳腺、肝脏和小腿肌肉样本并迅速冷冻。脱蛋白后，在LKB 4400氨基酸分析仪上测定游离氨基酸。随着日粮蛋白质营养价值的提高，产奶量增加了两倍，乳腺中游离赖氨酸水平增加了六至八倍。随着蛋白质质量或数量的改善，游离蛋氨酸水平增加了两至三倍，乳腺中游离苏氨酸、芳香族和支链氨基酸水平未见一致变化。乳腺、肝脏和肌肉中的游离赖氨酸浓度与血清中的游离赖氨酸高度相关（r2分别为0.94、0.96、0.93）。在本实验条件下，观察到日粮赖氨酸、乳腺中游离赖氨酸与乳汁分泌之间存在直接关系。
