本研究先后通过2个梯度试验来研究低蛋白质饲粮条件下生长猪对色氨酸的需要量。试验分别选取360头平均初始体重为（24.16±2.35） kg和（23.60±2.17） kg的“杜×长×大”三元杂交健康生长猪，随机分为6个处理，每个处理6个重复，每个重复10头猪。对照组饲粮参照NRC（1998）猪营养需要量推荐标准设计，蛋白质含量为正常水平；试验组饲粮的蛋白质水平较对照组饲粮降低4个百分点，各试验组的真可消化赖氨酸、真可消化蛋氨酸、真可消化苏氨酸的含量和净能水平保持一致；试验1中真可消化色氨酸设0.131%、0.146%、0.161%、0.176%和0.191% 5个水平，试验2中真可消化色氨酸设0.141%、0.150%、0.159%、0.170%和0.181% 5个水平；对照组饲粮真可消化赖氨酸、含硫氨基酸、真可消化苏氨酸含量和净能水平与试验组接近。结果表明，在氨基酸平衡时，饲粮蛋白质水平较NRC（1998）猪营养需要量推荐标准降低4个百分点并不影响试猪的生长性能；折线模型和二次回归分析结果显示，低蛋白质饲粮中真可消化色氨酸水平为0.146%时，试猪可获得最佳生长性能，超过0.152%时，试猪的生长性能有降低趋势，饲粮中真可消化赖氨酸与色氨酸的适宜比例为100∶ （17.6~18.3）。结果提示，饲粮蛋白质水平较NRC（1998）猪营养需要量推荐标准降低4个百分点，回肠真可消化赖氨酸为0.83%时，真可消化色氨酸水平为0.146%可以较好满足生长猪（20~50 kg）的生长需要。
Two experiments were conducted to determine requirements of tryptophan (Trp) for growing pigs fed low protein diets supplemented with crystalline amino acids (CAA). A total of 360 cross-bred (Duroc×Landrace×Large white) growing pigs [(24.16±2.35) kg, experiment 1] or 360 cross-bred (Duroc×Landrace×Large white) growing pigs [(23.60±2.17) kg, experiment 2] were allotted to 6 treatments with 6 replicates in each treatment and 10 growing pigs in each replicate. In experiment 1, the treatments consisted of a corn and soybean meal control diet meeting the nutrient requirements of swine (NRC, 1998) and five test diets with the same low protein content (4% reduction) and five different Trp levels (0.131%, 0.146%, 0.161%, 0.176% and 0.191%, respectively) supplemented with CAA. In experiment 2, a control diet was the same as that in the experiment 1, and five test diets had the same low protein content (4% reduction) and five different Trp levels (0.141%, 0.150%, 0.159%, 0.170%, and 0.181%, respectively). The results showed that no adverse effects on growth performance were found in growing pigs fed the low protein (4% reduction) diets with CAA supplementation. The results of broken line model and quadratic regression analysis indicated that to achieve maximum growth performance in growing pigs, 0.146% Trp in the low protein (4% reduction) diet with CAA supplementation was necessary, but not greater than 0.152%, and TDLys∶ TDTrp = 100∶（17.6 to 18.3） was a suitable scope. The results indicate that feeding a low protein (4% reduction) diet, optimum growth performance of growing pigs (20 to 50 kg) will be obtained if the diet provides 0.146% Trp, as well as 0.83% ileum true digestible lysine.［Chinese Journal of Animal Nutrition, 2011, 23（10）：1669 -1676］
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