Svihus B
Norwegian University of Life Sciences, PO Box 5003, N-1432 Aas, Norway
Poult Sci. 2014 Sep;93(9):2394-9. doi: 10.3382/ps.2014-03905. Epub 2014 Jul 10.
Starch is quantitatively the most important nutrient in poultry diets and will to a large extent be present as intact starch granules due to very limited extent of gelatinization during pelleting. Although native starch is difficult to digest due to a semi-crystalline structure, even fast-growing broiler chickens appears to be able to digest this starch more or less completely during passage through the jejunum. However, reduced starch digestibility has been observed, particularly in pelleted diets containing large quantities of wheat. Although properties of the starch granule such as size and components on the granule surface may affect digestibility, the entrapment of starch granules in cell walls and a protein matrix may be even more important factors impeding starch digestion. In that case, this and the fact that amylase secretion is normally very high in poultry may explain the lack of convincing effects of exogenous α-amylase added to the diet. However, few well-designed experiments assessing mechanisms of starch digestion and the effect of α-amylase supplementation have been carried out, and thus more research is needed in this important area.
淀粉在禽类日粮中是数量上最重要的营养物质，由于制粒过程中糊化程度非常有限，淀粉很大程度上会以完整的淀粉颗粒形式存在。尽管天然淀粉因半结晶结构难以消化，但即使是快速生长的肉鸡在通过空肠时似乎也能或多或少地完全消化这种淀粉。然而，已观察到淀粉消化率降低，尤其是在含有大量小麦的颗粒饲料中。尽管淀粉颗粒的特性（如大小和颗粒表面成分）可能会影响消化率，但淀粉颗粒被困在细胞壁和蛋白质基质中可能是阻碍淀粉消化的更重要因素。在这种情况下，这一点以及禽类淀粉酶分泌通常非常高这一事实，可能解释了添加到日粮中的外源α-淀粉酶缺乏令人信服的效果。然而，很少有精心设计的实验来评估淀粉消化机制和α-淀粉酶补充的效果，因此在这个重要领域需要更多的研究。
