Langer S, Fuller M F
Rowett Research Institute, Bucksburn, Aberdeen.
Br J Nutr. 1996 Nov;76(5):743-54. doi: 10.1079/bjn19960080.
Two experiments were conducted to investigate whether the utilization of lysine in growing pigs is affected by the level of excess protein in the diet. Nine lysine-deficient diets containing 100, 200 or 300 g crude protein/kg and between 1.2 and 6.8 g ileal digestible lysine/kg were prepared. In the first experiment the apparent ileal digestibility of lysine in three of the nine diets was determined using pigs with simple T-cannulas and Cr2O3 as an indigestible marker. Ileal digestibility of lysine in the other diets was calculated by interpolation. In the second experiment N retention, as a measure of lysine utilization, was determined in all nine diets using growing pigs over the weight range 30-50 kg. The effect of excess protein on lysine utilization was assessed by comparing the regression of N retention v. lysine (ileal digestible) intake at the three levels of protein. Increasing ileal digestible lysine in the diets resulted in a linear increase in N retention with all three protein levels and there was no significant difference amongst the three regressions, indicating that lysine utilization was not affected by the level of protein. Therefore, all data were pooled together to calculate a single regression for all treatments. An increase of 1.0 g ileal digestible lysine led to an increase of 1.43 g N or 8.96 g protein (N x 6.25) retained. Assuming a lysine concentration in the retained body protein of 65-72 mg/g, lysine was utilized with an efficiency of 0.58-0.65.
进行了两项试验，以研究生长猪日粮中过量蛋白质水平是否会影响赖氨酸的利用率。制备了9种赖氨酸缺乏日粮，其粗蛋白含量分别为100、200或300 g/kg，回肠可消化赖氨酸含量在1.2至6.8 g/kg之间。在第一项试验中，使用安装简单T型瘘管的猪和以三氧化二铬作为不消化标记物，测定了9种日粮中3种日粮的赖氨酸表观回肠消化率。其他日粮的赖氨酸回肠消化率通过插值法计算。在第二项试验中，使用体重范围为30至50 kg的生长猪，测定了所有9种日粮的氮保留量，作为赖氨酸利用率的指标。通过比较三种蛋白质水平下氮保留量与赖氨酸（回肠可消化）摄入量的回归关系，评估过量蛋白质对赖氨酸利用率的影响。日粮中回肠可消化赖氨酸增加，导致三种蛋白质水平下氮保留量均呈线性增加，且三种回归关系之间无显著差异，表明赖氨酸利用率不受蛋白质水平的影响。因此，将所有数据合并在一起，计算所有处理的单一回归方程。回肠可消化赖氨酸每增加1.0 g，氮保留量增加1.43 g或蛋白质（氮×6.25）保留量增加8.96 g。假设保留的体蛋白中赖氨酸浓度为65 - 72 mg/g，则赖氨酸的利用率为0.58 - 0.65。
