Lin F D, Smith T K, Bayley H S
J Anim Sci. 1986 Mar;62(3):660-4. doi: 10.2527/jas1986.623660x.
The tryptophan requirement of growing swine was determined using the oxidation of L-[1-14C]-phenylalanine as an indicator of the adequacy of the dietary tryptophan level. Forty crossbred boars (30 to 45 kg) were fed a basal diet containing 16% protein supplied by corn and gelatin. A series of experimental diets containing .05, .08, .10, .15, .20 and .25% L-tryptophan were prepared. The diets were supplemented with crystalline amino acids to provide 135% of the recommended levels. Release of 14CO2 was measured for 1 h following a meal of the experimental diet containing 20 microCi 14C phenylalanine. Increasing dietary tryptophan from .05 to .13% decreased release of 14CO2. Further increases in dietary tryptophan concentration did not significantly influence 14CO2 production. Regression analysis using a two-phase linear regression crossover model indicated that phenylalanine oxidation was minimized by a dietary tryptophan concentration of .13%. It was concluded that at a concentration of .13%, tryptophan was no longer limiting the retention of the other amino acids, thus this is the requirement for maximum protein retention by the young, growing boar.
利用L-[1-¹⁴C]-苯丙氨酸的氧化作为日粮色氨酸水平是否充足的指标，测定生长猪的色氨酸需求量。选用40头杂交公猪（体重30至45千克），饲喂由玉米和明胶提供16%蛋白质的基础日粮。配制了一系列分别含有0.05%、0.08%、0.10%、0.15%、0.20%和0.25%L-色氨酸的试验日粮。日粮中添加结晶氨基酸，使其含量达到推荐水平的135%。在饲喂含有20微居里¹⁴C苯丙氨酸的试验日粮后1小时，测定¹⁴CO₂的释放量。日粮色氨酸含量从0.05%增加到0.13%，可降低¹⁴CO₂的释放量。日粮色氨酸浓度进一步增加对¹⁴CO₂的产生没有显著影响。使用两阶段线性回归交叉模型进行回归分析表明，日粮色氨酸浓度为0.13%时，苯丙氨酸氧化降至最低。得出的结论是，色氨酸浓度为0.13%时，不再限制其他氨基酸的保留，因此这是幼年生长公猪最大蛋白质保留量的需求量。
