Absorption capacity of chicken intestine for d-xylose in response to graded concentrations of tannic acid

Dietary tannins alter the mechanisms involved in cellular uptake and transport of simple sugars. An experiment was conducted on broiler chickens to evaluate the absorptive response of intestine to the graded concentrations of tannic acid (TA), using d-xylose absorption test. Four groups of ten 28-d-old broiler cockerels, were given d-xylose solution alone (500 mg kg−1 BW, group 1) and with TA solution at a dose of 0.5, 1.0 and 1.5 g/bird (groups 2–4, respectively), orally. One blood samples prior-to, and four others after administration of test material, were collected by ulnar vein puncture on 40 min basis for 160 min, and the concentration of d-xylose in plasma was measured. The plasma d-xylose concentration in each group had a quadratic correlation with time (P<0.001, R2 = 0.75, 0.84, 0.73 and 0.84 for groups 1–4, respectively). Tannic acid delayed and severely suppressed the intestinal absorption of d-xylose in groups 2–4 (P<0.001). The plasma d-xylose concentration of group was negatively related to the level of dosed TA with an exponential trend at each time of blood sampling (R2 = 0.88, 0.87, 0.86 and 0.83 for 40, 80, 120 and 160 min post-ingestion of TA solution, respectively). Tannic acid showed to be a strong luminal inhibitor of sugar absorption. However, the ingestion of higher concentrations of TA (1.5 g/bird) did not further reduce the concentration of plasma d-xylose suggesting the influence of TA on the intestinal absorption capacity was dose-dependent in an exponential manner.