Although the protein content of swine diets is formulated based on the ileal digestibility of protein and amino acids (AA) under current nutrition requirements, the nitrogen utilization efficiency of swine varies based on protein source, which may be related to AA release kinetics. In this experiment, a 2 × 2 factorial arrangement with casein (CAS)-enriched or corn gluten meal (CGM)-enriched protein sources at different digestible crude protein levels (normal [N], 13%; and low [L], 11%) were applied to 24 crossbred (Duroc × Landrace × Yorkshire) growing pigs (average body weight = 43.3 ± 3.5 kg) in 4 treatments (N.CAS, L.CAS, N.CGM, L.CGM, respectively) to investigate the effects of AA release kinetics on nitrogen deposition in growing pigs. Standardized ileal digestible AA in all diets were balanced by adding individual AA to meet the nutrient requirements. The AA release kinetics were detected in vitro by measuring the hydrolysis of various protein diets under pepsin and trypsin conditions. The results demonstrated that the time of AA release peak in the CGM diet was 12 h later than that in the CAS diet. The synchronization indices of dietary AA release in N.CAS, N.CGM, L.CAS, and L.CGM were 23.73%, 29.37%, 23.40%, and 26.07%, respectively. The N.CGM had the poorest AA release synchronism while the N.CAS had the greatest among the 4 diets. However, within the pigs, L.CAS and N.CGM showed the highest (81.08%) and lowest (73.54%) nitrogen biological values, respectively, despite the standard ileal digestible AA levels being equal for all diets. These results indicate that the release kinetics of dietary AA had great effect on nitrogen deposition. To optimize nitrogen deposition, AA release kinetics and composition should be taken into consideration when formulating diets for growing pigs.

虽然猪日粮的蛋白质含量是根据当前营养需求下蛋白质和氨基酸（AA）的回肠消化率制定的，但猪的氮利用效率因蛋白质来源而异，这可能与氨基酸释放动力学有关。在本实验中，在不同可消化粗蛋白水平（正常 [N]，13%；低 [L]，11 %）在 4 个处理（分别为 N.CAS、L.CAS、N.CGM、L.CGM）中应用于 24 头杂交（Duroc × Landrace × Yorkshire）生长猪（平均体重 = 43.3 ± 3.5 kg）进行研究AA释放动力学对生长猪氮沉降的影响。通过添加单个 AA 来平衡所有日粮中的标准化回肠可消化 AA 以满足营养需求。通过在胃蛋白酶和胰蛋白酶条件下测量各种蛋白质饮食的水解，体外检测 AA 释放动力学。结果表明，CGM 日粮中 AA 释放峰值的时间比 CAS 日粮晚 12 h。N.CAS、N.CGM、L.CAS和L.CGM日粮AA释放同步指数分别为23.73%、29.37%、23.40%和26.07%。N.CGM 具有最差的 AA 释放同步性，而 N.CAS 在 4 种饮食中具有最大的同步性。然而，在猪体内，L.CAS 和 N.CGM 分别显示出最高 (81.08%) 和最低 (73.54%) 的氮生物学值，尽管所有日粮的标准回肠可消化 AA 水平相同。这些结果表明日粮AA的释放动力学对氮沉降有很大的影响。为了优化氮沉积，在为生长猪配制日粮时应考虑 AA 释放动力学和成分。