本试验旨在简化基于康奈尔净碳水化合物与蛋白质体系（CNCPS）评定瘤胃非降解蛋白质（RUP）小肠可吸收氨基酸流量的技术。小肠可吸收氨基酸来自菌体蛋白和RUP，CNCPS根据溶解性将饲料粗蛋白质（CP）分为A、B1、B2、B3和C共5种组分，只有3种B组分可以过瘤胃并在小肠中消化。为评定RUP小肠可吸收氨基酸的贡献，CNCPS需要分别测定3种B组分的瘤胃降解率，3种过瘤胃B组分的小肠消化率需采用不同常数。选择18份饲料样品，其中精料12份，粗料6份，测定CNCPS评定RUP小肠可吸收氨基酸流量所需数据，同时对饲料CP的瘤胃动态降解率及不同时间点RUP的体外小肠消化率进行了测定，通过这些数据提出简化评定方法。结果表明：1）精料和粗料均以8 h的CP瘤胃降解率（X，%）与有效降解率（Y，%）间相关性最强，二者间呈线性相关，精料和粗料方程分别为Y=12.652+0.828X，r=0.990，P<0.000 1和Y=10.967+0.886X，r=0.980，P=0.000 6。2）精料2 h RUP小肠消化率（X，%）与RUP小肠有效消化率（Y，%）间相关性最强，方程为Y=0.026+0.879X，r=0.970，P<0.000 1；粗料8 h RUP小肠消化率（X，%）与RUP小肠有效消化率（Y，%）间相关性最强，方程为Y=-0.002+0.960X，r=0.995，P<0.000 1。3）简化方案经可靠性评估得出，8 h CP瘤胃降解率和RUP小肠消化率简化CNCPS模型预测的小肠氨基酸流量（X，‰）与CNCPS预测的小肠氨基酸流量（Y，‰）相关性最强，精料方程为Y=-0.056+1.409X，r=0.999，P<0.000 1；粗料方程为Y=0.003+2.120X，r=0.999，P<0.000 1。精料和粗料的简化评定结果与CNCPS评定结果的均方根误差分别为0.245和0.005，变异系数分别为7.08%和4.49%。综合得出，基于CNCPS，得到了预测RUP小肠可吸收氨基酸流量的简化模型，简化后的精料和粗料模型分别为Y=-0.056+1.409×[AA×（100-D₈）×CP×ID₈]，r=0.999，P<0.000 1和Y=0.002+2.120×[AA×（100-D₈）×CP×ID₈]，r=0.999，P<0.000 1，Y为RUP中的某种氨基酸小肠可吸收流量（‰），D₈为CP的8 h瘤胃降解率（%），ID₈为RUP的8 h小肠消化率（%），AA为不溶性蛋白质中该氨基酸含量（%）。

This study was conducted to simplify the assessment technology of intestinal absorbed amino acids fluxes of rumen undegradable protein (RUP) based on Cornell net carbohydrate and protein system (CNCPS). Intestinal absorbed amino acids were consisted of microbial protein and RUP. Crude protein (CP) was divided into A, B1, B2, B3 and C in CNCPS based on solubility, only B fractions could pass rumen and be digested in intestine. To estimate the contribution of intestinal absorbed amino acids from RUP, CNCPS model needed the degradability of B fractions, and intestinal digestibility of B fractions used different constants. This study collected 18 kinds of feedstuffs including 12 kinds of concentrate and 6 kinds of roughage. The data for measuring RUP intestinal absorbed amino acids fluxes in CNCPS was determined, and it was also determined that ruminal degradability of CP and intestinal digestibility of RUP at different time points. Based on the above data, simplification methods were concluded. The results showed as follows:1) CP ruminal degradability at 8 h (X,%) and effective degradability (Y,%) got the highest correlation with linear correlation both in concentrates and roughages. The equations for concentrates and roughages were Y=12.652+0.828X, r=0.990, P<0.000 1 and Y=10.967+0.886X, r=0.980, P=0.000 6, respectively. 2) CP intestinal digestibility of residues retained in rumen for 2 h (X,%) got the highest correlation with RUP intestinal effective digestibility (Y,%) for concentrates, and the equation was Y=0.026+0.879X, r=0.970, P<0.000 1; CP intestinal digestibility of residues retained in rumen for 8 h (X,%) got the highest correlation with RUP intestinal effective digestibility (Y,%) for roughages, and the equation was Y=-0.002+0.960X, r=0.995, P<0.000 1. 3) After reliability assessment, the highest correlations were found in intestinal absorbed amino acids predicated by simplified CNCPS models using ruminal degradability and CP intestinal digestibility of residues retained in rumen at 8 h (X, ‰) and CNCPS (Y, ‰), and the equations for concentrates and roughages were Y=-0.056+1.409X, r=0.999, P<0.000 1 and Y=0.003+2.120X, r=0.999, P<0.000 1, respectively. The root-mean-square phase errors were 0.245 and 0.005, respectively, and the coefficients of variation were 7.08% and 4.49%, respectively. In conclusion, simplified predation models for RUP intestinal absorbed amino acids fluxes are set based on CNCPS, and the simplified modes for concentrates and roughages are Y=-0.056+1.409×[AA×(100-D₈)×CP×ID₈], r=0.999, P<0.000 1 and Y=0.002+2.120×[AA×(100-D₈)×CP×ID₈], r=0.999, P<0.000 1, respectively[Y is RUP intestinal absorbed amino acid flux (‰), D₈ is CP ruminal degradability at 8 h (%), ID₈ is RUP intestinal digestibility at 8 h (%), AA is amino acid content in insoluble protein (%)].