The incorporation of whole grain into pelleted broiler chicken diets. II. Gastrointestinal and digesta characteristics.

1. Pelleted diets, incorporating whole or ground wheat or barley in the pellets, were fed to broiler chickens and the performance, gastrointestinal development and digesta characteristics of those chickens recorded. 2. Body weight was similar with whole grain incorporation or enzyme application. Food conversion efficiency was improved by addition of enzyme to a full wheat diet. 3. Whole grain inclusion in pellets reduced proventriculus proportional mass and increased gizzard proportional mass with no apparent effects of exogenous feed enzyme addition. 4. Relative ileal mass was reduced by enzyme inclusion in a wheat diet and by inclusion of whole barley in the pellets. 5. Digesta viscosity was increased by whole wheat inclusion but reduced by enzyme inclusion irrespective of grain processing. Inclusion of 200 g/kg of barley did not alter viscosity of digesta beyond the duodenum. 6. Fresh excreta pH was higher with both cereals in the grower phase when whole grain was fed. On the barley diet, this was affected by enzyme addition, which created higher pH from a point earlier in the grower phase than when no enzyme was employed. 7. Evidence of a complex interaction between higher viscosity and pH being involved in differences in ileal relative mass was found through significant relationships being produced by enzyme use on the wheat diet alone.