Reduction of crude protein (CP) content in swine diets must be associated with an adequate quantitative and qualitative provision of amino acids (AA). In piglet diets, the fifth limiting AA is Val, where deficiency has been proven to reduce feed intake. In addition, depending on the overall level of CP and AA, diets high or low in standardized ileal digestible (SID) Lys will have different branched chain amino acid (BCAA) balances, which may in turn affect the feed intake response. Therefore, two Lys dose response trials (Exp. 1 and 2) were performed to study the influence of different AA concentrations on feed intake and overall performance. CP levels differed between the two experiments (201–210 g/kg in Exp. 1 and 180 g/kg in Exp. 2). Next, one Val dose response (Exp. 3) was carried out to establish the optimal SID Val:Lys ratio for 4 to 9-week-old Piétrain piglets. In Exp. 1, raising dietary SID Lys from 8.50 to 13.50 g/kg resulted in a significant linear and quadratic increase of average daily gain (ADG) and gain to feed (G:F) (P < 0.001 and P < 0.01 respectively), while average daily feed intake (ADFI) showed a linear increase with increasing SID Lys levels (P < 0.001), with a tendency to a quadratic effect (P = 0.08). In Exp. 2, ADG and G:F responded linearly and quadratically to SID Lys levels from 8.50 to 13.50 g/kg (P < 0.001), and ADFI showed a quadratic (P < 0.001) but not linear (P = 0.144) response to increased dietary SID Lys. For Exp. 1, the break points were above the tested SID range. For Exp. 2, quadratic polynomial (QP) and broken line quadratic (BLQ) model for ADG gave an optimal SID Lys of 12.05 and 11.39 g/kg, respectively, the QP ADFI reached an optimum of 11.33 g/kg of SID Lys. For G:F an optimal SID Lys level of 13.23, 11.72, and 13.28 g/kg SID Lys were estimated with a QP, broken line linear (BLL), and BLQ respectively. In Exp. 3, increasing the dietary SID Val:Lys level resulted in a linear and quadratic increase of ADG and ADFI (P < 0.001), but not G:F (P = 0.626 and P = 0.114). For ADG and ADFI it was possible to fit a QP and a BLQ model, with an optimal SID Val:Lys of 0.74 for the QP and 0.68 for the BLQ model, respectively, for the two response variables. In conclusion, SID Lys requirements of 4 to 9-week-old piglets are estimated to be equal or greater than 11.4 g/kg (1.14%), and SID Val:Lys requirements were found to be between 68 and 74% for optimal growth and feed intake.

猪日粮中粗蛋白（CP）含量的减少必须与氨基酸（AA）的定量和定性的充足提供相关。在仔猪日粮中，第五个限制性AA是Val，已证明缺乏可降低饲料摄入量。此外，根据CP和AA的总体水平，标准化回肠易消化（SID）Lys的日粮中的高或低将具有不同的支链氨基酸（BCAA）平衡，这反过来可能会影响采食量。因此，进行了两项Lys剂量反应试验（实验1和2），以研究不同AA浓度对采食量和总体性能的影响。两次实验之间的CP水平有所不同（实验1中为201-210 g / kg，实验2中为180 g / kg）。接下来，进行一次Val剂量反应（实验3）以建立最佳SID Val：4至9周大的Piétrain仔猪的赖氨酸比。在实验中 如图1所示，将膳食SID Lys从8.50 g / kg提高到13.50 g / kg，导致平均日增重（ADG）和饲料增重（G：F）呈线性和二次线性增长（分别为P <0.001和P <0.01），而平均每日饲料摄入量（ADFI）随SID Lys水平的升高呈线性增加（P <0.001），并且具有二次效应的趋势（P  = 0.08）。在实验中 2，ADG和G：F对SID Lys水平从8.50到13.50 g / kg呈线性和二次响应（P <0.001），ADFI显示为二次（P <0.001）但不是线性（P = 0.144）对日粮SID Lys升高的反应。对于Exp。如图1所示，断点高于测试的SID范围。对于Exp。如图2所示，ADG的二次多项式（QP）和折线二次（BLQ）模型分别给出了12.05和11.39 g / kg的最佳SID Lys，QP ADFI达到了11.33 g / kg的SID Lys最佳值。对于G：F，分别通过QP，虚线线性（BLL）和BLQ估计最佳SID Lys水平为13.23、11.72和13.28 g / kg SID Lys。在实验中 3，增加饮食中的SID Val：Lys水平会导致ADG和ADFI呈线性和二次增加（P <0.001），但不会导致G：F（P  = 0.626和P = 0.114）。对于ADG和ADFI，可以拟合QP和BLQ模型，两个响应变量的最佳SID Val：Lys对于QP分别为0.74，对于BLQ模型为0.68。总之，估计4至9周龄仔猪的SID Lys需求量等于或大于11.4 g / kg（1.14％），SID Val：Lys需求量在68％至74％之间以获得最佳生长和采食量。