Monitoring the stepwise phytate degradation in the upper gastrointestinal tract of pigs

• Published in: Journal of the science of food and agriculture 2006-03, Vol.86 (4), p.612-622
• Main Authors: Kemme, P.A, Schlemmer, U, Mroz, Z, Jongbloed, A.W
• Format: Article
• Language: English
• Subjects: absorption; Animal productions; apparent digestibility; Aspergillus niger; aspergillus-niger phytase; Biological and medical sciences; digestion; Digestive system; dosage; dry-matter; duodenum; enzyme activity; Enzymes; Feed science; Feeds; food animals; Food industries; Fundamental and applied biological sciences. Psychology; gastrointestinal system; growing pigs; Hogs; ileum; inositol phosphates; intestinal absorption; intestinal microorganisms; microbial activity; microbial phytase; phytase; phytases; phytate; phytic acid; pigs; plant phytase; small-intestine; spatial variation; stomach; swine; Terrestrial animal productions; uptake mechanisms; Vertebrates
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/jsfa.2380

The degradation and formation of inositol phosphates as affected by microbial phytase and gastrointestinal enzyme activities during the passage of phytate through the stomach and small intestine were studied in two experiments with four barrows and three collection periods. The degradation and formation of inositol phosphates were measured at the duodenal and ileal sites using Cr-NDR, TiO2 and Co-EDTA as indigestible markers. In experiment 1, the effect of graded doses of Aspergillus niger phytase (0, 150 and 900 FTU Natuphos kg-1), added to a maize-soybean meal-based diet with very low intrinsic phytase activity on the degradation of phytate and the formation of inositol phosphates during digestion in the stomach and small intestine was investigated. In experiment 2, three different mixtures of inositol phosphates, produced by Aspergillus niger phytase, containing mainly high, intermediate and low phosphorylated inositol phosphates, were added to the same maize-soybean meal-based diet as used in experiment I. The fate of the inositol phosphates during digestion in the stomach and small intestine was studied. Experiment 1 showed that the extent of phytate degradation was dependent of the graded dietary phytase activities. At high phytase activity (900 FTU kg-1 of diet), strong phytate degradation occurred and the once hydrolysed phytate was rapidly dephosphorylated to lower inositol phosphates (mainly inositol di- and triphosphates). Intermediate inositol phosphates, such as inositol tetraphosphates, were quantitatively unimportant in duodenal and ileal digesta. At a phytase activity of 150 FTU kg-1 of diet, a broader spectrum of intermediate inositol phosphates was determined, which was probably due to a slower breakdown of phytate. Experiment 2 showed as a predominant result that lower inositol phosphates such InsP4 and InsP3 were degraded, whereas InsP2 accumulated in the duodenal and ileal digesta. No substantial disappearance of phytate from the stomach and small intestine was found when high concentrations of soluble phytate were added to the diet, which indicates that no substantial phytate absorption occurs in the upper part of the pig gut.