EFFECTS OF ENDOXYLANASE ADDITION TO WHEAT-BASED DIETS ON PHYSICOCHEMICAL CHYME CONDITIONS AND MINERAL ABSORPTION IN BROILERS

Four wheat cultivars, differing in in vitro viscosity and water-solubl e arabinoxylan content, were added to a basal diet on a 50:50 weight b asis. These wheat-based diets were fed to male broilers from 3 weeks o f age, with and without the addition of 75 mg endoxylanase (70 000 EXU g(-1) enzyme) per kg feed. The broilers were killed at 4.5 weeks of a ge, and the jejunal and ileal contents were sampled. The absorption of sodium, potassium, calcium, phosphorus, and magnesium was calculated based on the contents of the last 10 cm of these intestinal segments, using Cr2O3 as a reference substance. The pH, osmolality and viscosity were measured in the remaining jejunal and ileal contents. Dietary ad dition of high viscosity wheats (HVW) resulted in higher intraluminal viscosities than on the low viscosity wheat (LVW) diets. The osmolalit y of the chyme supernatant of the birds fed the HVW diets declined les s as the chyme moved from the jejunum into the ileum, compared with th e LVW diets. This indicates a less efficient absorption of osmo-active soluble chyme components at higher intraluminal viscosities, as compl ex formation in the intestinal lumen could not account for this effect . Linear regression analysis revealed a clear negative relationship be tween the viscosity of the chyme supernatant and the absorption of dry matter and minerals in either one or both of the intestinal segments. Addition of endoxylanase lowered the viscosity of the chyme supernata nt to similar levels on all wheat-based diets. Furthermore, is enhance d the apparent absorption of calcium, magnesium, sodium and potassium from the jejunal lumen. However, at the lower ileal level only magnesi um absorption was improved by dietary endoxylanase addition.