This study was conducted to investigate the effect of protease inclusion level in two different ages on the apparent (AID) and standardized (SID) ileal digestibility of crude protein (CP) and amino acids (AA) in soybean meal (SBM) fed to growing-finishing pigs. Ten cannulated pigs (21 kg ± 2 kg) were assigned to experimental diets in a duplicate 5 × 5 Latin square design. In Phase I (23 to 30 kg-pigs, 90 ± 17 days of age), ileal digesta was collected in 5 periods of 7d (5d adaptation and 2d ileal digesta collection). In phase II, (50 to 65 kg-pigs, 140 ± 17 days of age), ileal digesta was collected in 5 more periods of 7 d. For both phases, a corn starch–based diet was formulated with SBM as the sole source of CP and AA and containing titanium as an indigestible marker. Protease was supplemented at 0, 15,000, 30,000, and 45,000 NFP/kg of feed (0, 25, 50, and 75 g/ton of ProAct 360®). A nitrogen-free diet was used to estimate basal ileal endogenous AA losses. Pigs were fed at 4% of their body weight, which was adjusted at the end of each period. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary protease supplementation in each phase. In phase I, increasing levels of protease resulted in a linear increase (P<0.10) in SID for the 7/11 indispensable AA (Except Arg, His, Met + Cys, and Trp) and the average of all dispensable AA. In phase II, the SID of Ile, Leu, Met, Met + Cys, Val, the average of all indispensable AA, and 4/7 dispensable AA were quadratically increased (P<0.10). In most cases, supplementation with 30,000 NFP/ kg of feed (50 g/ton) resulted in the greatest increase in AA digestibility. However, the linear response in phase I for some AA suggests that diets for younger pigs could be supplemented with a greater level (45,000 NFP/kg or 75 g/Ton of feed). Interestingly, younger pigs had consistently increased (P<0.10) SID of CP and 15/18 AA (Except Arg, Cys, and Ser), being ~5.6% greater for indispensable AA when compared to older pigs. In conclusion, dietary protease supplementation can increase the SID of AA in soybean meal in both growing and finishing periods. Pig age can potentially influence AA digestibility, possibly related to a greater ileal endogenous AA flow in younger pigs. However, this fact warrants further investigation.

中文翻译：

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蛋白酶添加对2个不同日龄生长育肥猪饲喂豆粕氨基酸消化率的影响


本研究旨在探讨两个不同日龄蛋白酶包涵水平对饲喂生长育肥猪豆粕 （SBM） 粗蛋白 （CP） 和氨基酸 （AA） 的表观 （AID） 和标准化 （SID） 回肠消化率的影响。将 10 头空心猪 （21 kg ± 2 kg） 分配到实验日粮中，采用 5 × 5 拉丁方设计。在第一阶段 （23 至 30 公斤猪，90 ± 17 日龄），在 5 个 7 天 （5 天适应和 2 天回肠消化物收集） 中收集回肠消化物。在第二阶段 （50 至 65 公斤猪，140 ± 17 日龄），在另外 5 个 7 天的周期中收集回肠消化物。对于这两个阶段，以玉米淀粉为基础的饮食以 SBM 作为 CP 和 AA 的唯一来源，并含有钛作为难以消化的标志物。蛋白酶添加量为 0、15,000、30,000 和 45,000 NFP/kg 饲料（0、25、50 和 75 g/ton ProAct 360®）。无氮饮食用于估计基底回肠内源性 AA 丢失。猪以体重的 4% 饲喂，在每个时期结束时进行调整。使用正交多项式对比来确定每个阶段日粮蛋白酶补充剂的线性和二次效应。在第一阶段，蛋白酶水平的增加导致 7/11 个不可缺少的 AA（Arg、His、Met + Cys 和 Trp 除外）的 SID 线性增加 （P<0.10） 和所有可有可无的 AA 的平均值。II 期，Ile、Leu、Met、Met + Cys、Val 的 SID 、所有必需的 AA 的平均值和 4/7 的可有可无 AA 呈二次增加 （P<0.10）。在大多数情况下，添加 30,000 NFP/kg 饲料（50 g/ton）可最大程度地提高 AA 消化率。 然而，一些 AA 在 I 阶段的线性响应表明，年轻猪的日粮可以补充更高水平的饲料（45,000 NFP/kg 或 75 g/Ton 饲料）。有趣的是，年轻猪的 CP SID 和 15/18 AA（Arg、Cys 和 Ser 除外）持续增加 （P<0.10），与老猪相比，必需的 AA 高出 ~5.6%。综上所述，日粮蛋白酶添加可增加豆粕中 AA 在生长期和育肥期的 SID。猪龄可能影响 AA 消化率，可能与年轻猪回肠内源性 AA 流量增加有关。然而，这一事实值得进一步调查。