Fermentation in vitro of a mixture of dietary fibers and cane molasses by the cecal microbiota: Application on mineral absorption through the laying hen's colonic epithelium

Short-chain fatty acid (SCFA) production from a mixture of dietary fibers and cane molasses fermentation by laying hens’ cecal microbiota and calcium and iron absorption through the colonic mucosa driven by these acids were studied in vitro. Oligofructose, polydextrose or arabic gum at concentrations of 10 g/L of cecal suspension, alone or combined with molasses in a 1:1 (w/v) relation were assayed. Fermentation of molasses and oligofructose by hens’ cecal microbiota significantly increased SCFA production; a similar effect was also observed with polydextrose and arabic gum, but to a lower extent. The highest level was attained by cecal fermentation of combined molasses–oligofructose, suggesting a complementary effect of these fibers in the mixture. SCFA mixtures with acid levels similar to that derived from the fermentation of molasses, oligofructose or a combination of both had a positive influence on mineral absorption by the colonic mucosa when assayed in an Ussing chamber. The best result was achieved with a SCFA concentration that simulated that of the molasses–oligofructose mix fermentation as the amount of calcium and iron absorbed grew approximately eightfold when compared to the one in the absence of SCFA. Different SCFA, in a range of concentrations similar to those derived from colonic fermentation without fiber addition, increased ionic absorption which was dependent on acid type and concentration used, being more remarkable for butyric acid. The effectiveness in mineral absorption was lesser than the one obtained with SCFA mixtures derived from fiber fermentations as a consequence of lower amounts of acids. The results of this study suggest that molasses–oligofructose as a layers’ diet supplement could improve mineral absorption in the intestinal lumen.