Role of starch chemistry in the kinetics of nutrient absorption, endocrine profile, and intestinal health in swine.

摘要

Starch is a major source of energy for monogastric species. Although starch digestibility is understood, the role of starch chemistry on nutrient absorption, endocrine function and gut health is not. Therefore, the objective was to characterize the role of starches with a range in amylose content and rate of in vitro digestion on the kinetics of nutrient absorption, endocrine profile, and gut microbial profile in pigs. Four high (70%) starch diets differing in amylose contents (0, 19.6, 28.4 and 63.2%) and rates of in vitro digestibility (1.06; S2, 0.73; S3, 0.38 and S4, 0.22%/min; rapidly to slowly digestible starches) were formulated. In study 1, four portal vein-catheterized pigs were fed the starch diets and blood samples were collected from the portal vein, carotid artery and simultaneous blood flow was measured until 12 hour after feeding. In vitro rates of glucose release corrected for gastric emptying was strongly related (R2 = 0.95) to the kinetics of portal glucose absorption. Slowly digestible starch decreased glucose absorption and secretion of insulin and glucose-dependent insulinotropic polypeptide (GIP) but increased butyrate absorption and plasma betaine concentration. In study 2, fecal, ileal digesta, and urine samples were collected from eight ileal-canulated pigs fed the same diets. Slowly digestible starch decreased starch digestibility, increased total short chain fatty acids (SCFA) and butyrate production and selectively increased the population of bifidobacteria in the gut. In addition, mineral digestion and absorption in the large intestine compensated lower absorption of Ca, P, Na, and Fe in the small intestine of pigs fed slowly digestible starch. In summary, slowly digestible starch is energetically less efficient compared to rapidly digestible starch and the starch reduces glucose absorption and insulin secretion and increases the production of butyrate and the population of bifidobacteria. However, substantial changes of starch chemistry (at least ≥ 40% amylose content and ≤ 0.36%/min of maximum in vitro digestion rate) were required to have potentially beneficial changes in pigs.