The nutritive value of starch, the major source of dietary energy in pigs, varies depending on its susceptibility for digestion. The botanical origin of starch determines starch structure, and therefore, digestibility. To compare digestibility of starch, fiber, gross energy (GE), crude protein, and amino acid (AA), and to characterize undigested starch of grains in growing pigs, seven ileal-cannulated barrows (initial body weight, 30 kg) were fed six diets containing 96% of one of six test ingredients (three pulse grains: zero-tannin faba bean, green field pea, or mixed-cultivar chickpea; three cereal grains: hulled barley, hard red spring wheat, or hybrid yellow, dent corn), or a N-free diet in a 7 × 7 Latin square at 2.8 × maintenance digestible energy. Grain samples were ground with a hammer mill through a 2.78-mm screen. Amylose content ranged from 29% to 34% for pulse grains and from 22% to 25% for cereal grains. The apparent ileal digestibility (AID) of starch was greater (P < 0.05) in cereal (94% to 97%) than pulse grains (85% to 90%) and was lowest (P < 0.05) in faba bean (85.3%) followed by field pea (87.2%) and chickpea (90.1%). However, apparent total tract digestibility (ATTD) of starch of all tested grains was close to 100%. Apparent hindgut fermentability (AHF, as ATTD − AID) of starch was greater (P < 0.05) in pulse grains (9.9% to 15%) than cereal grains (3.3% to 4.8%). The AHF of total dietary fiber tended to be the greatest (P < 0.10) for corn (43.5%) and lowest for wheat (25.3%). The AHF of GE was greater (P < 0.05) in pulse grains (17% to 20%) than in cereal grains (9% to 11%) and resulted in greater (P < 0.05) digestible energy (DE) contribution from hindgut fermentation for pulse grains than cereal grains (0.9 vs. 0.5 Mcal/kg). Wheat had the greatest standardized ileal digestibility of total AA (90.2%; P < 0.05). Confocal laser scanning microscopy images revealed that 20% to 30% of starch granules of pulse grains were entrapped in protein matrixes. In scanning electron microscopy images, starch granules were larger in faba bean and field pea than cereal grains. Digesta samples revealed pin holes and surface cracks in starch granules of corn and wheat, respectively. In conclusion, hindgut fermentation of starch and fiber was greater in pulse grains than cereal grains resulting in a greater DE value despite lower ileal DE for pulse grain than cereal grains. Defining the digestible and fermentable fractions of starch may enhance the accuracy of equations to predict the net energy value of these feedstuffs.

中文翻译：

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豆类谷物的淀粉后肠发酵比生长猪的谷物更大

淀粉是猪日粮能量的主要来源，其营养价值取决于其对消化的敏感性。淀粉的植物来源决定了淀粉的结构，因此决定了消化率。为了比较淀粉、纤维、总能量 (GE)、粗蛋白和氨基酸 (AA) 的消化率，并表征生长猪谷物中未消化的淀粉，饲喂了 7 只回肠插管的公猪（初始体重，30 公斤）六种饮食，含有 96% 的六种测试成分之一（三种豆类：零单宁蚕豆、绿豌豆或混合品种鹰嘴豆；三种谷物：去壳大麦、硬红春小麦或杂交黄、马齿玉米)，或者在 7 × 7 拉丁方格中以 2.8 × 维持消化能进行无氮饮食。谷物样品用锤磨机通过 2.78 毫米筛网进行研磨。豆类谷物的直链淀粉含量为 29% 至 34%，谷类谷物的直链淀粉含量为 22% 至 25%。淀粉的表观回肠消化率 (AID) 在谷物 (94% 至 97%) 中高于 (P < 0.05) 比豆类 (85% 至 90%) 和在蚕豆中最低 (P < 0.05) (85.3) %）其次是豌豆（87.2%）和鹰嘴豆（90.1%）。然而，所有测试谷物的淀粉表观总消化道消化率 (ATTD) 接近 100%。豆类谷物（9.9% 至 15%）中淀粉的表观后肠发酵能力（AHF，如 ATTD - AID）高于（P < 0.05）谷物（3.3% 至 4.8%）。总膳食纤维的 AHF 往往最高（P < 0.10）玉米（43.5%）和小麦最低（25.3%）。GE 的 AHF 在豆类谷物（17% 到 20%）中高于（P < 0.05），在谷物中（9% 到 11%）并导致更大（P < 0.05）。0.05) 后肠发酵对豆类谷物的消化能 (DE) 贡献高于谷物（0.9 对 0.5 Mcal/kg）。小麦对总 AA 的标准化回肠消化率最高（90.2%；P < 0.05）。共聚焦激光扫描显微图像显示，20% 到 30% 的脉冲颗粒淀粉颗粒被包裹在蛋白质基质中。在扫描电子显微镜图像中，蚕豆和豌豆中的淀粉颗粒比谷物大。Digesta 样品分别揭示了玉米和小麦淀粉颗粒中的针孔和表面裂缝。总之，豆类谷物中淀粉和纤维的后肠发酵程度高于谷物，导致尽管豆类谷物的回肠 DE 值低于谷类谷物，但其 DE 值更大。