Nutrient utilization and functionality of the anterior digestive tract caused by intermittent feeding and inclusion of whole wheat in diets for broiler chickens

Abstract

Two experiments were carried out to study the effect of intermittent feeding, diet structure, and their interaction on the performance, feeding pattern, and digestive adaptation of broiler chickens. In experiment 1, 40 Cobb broiler chickens were fed, either ad libitum or intermittently, a commercial starter diet diluted with 150 g/kg of ground or whole wheat in a 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 one-hour feeding bouts/d and one 2-h feeding bout/d from d 14. No interaction was found between feed structure and feeding regimen for any of the measurements. Although BW gain was not significantly different among any of the treatments, birds given whole wheat or fed intermittently had significantly better feed efficiency than those given ground wheat and fed ad libitum. Inclusion of whole wheat instead of ground wheat also markedly increased (P < 0.001) the AMEn value and fecal starch digestibility. In experiment 2, 60 Ross broiler chickens were trained to meal feeding on a wheat-based diet containing a commercial phytase, and 5 birds were killed every 15 min after having access to feed, to collect crop contents. Phytate was gradually degraded in the crop, with a 50% reduction in inositol 6-phosphate after a 100-min retention time. In conclusion, these results indicate that broiler chickens have a remarkable ability to maintain growth rate during intermittent feeding because the crop is used as an intermediate storage organ, and that improvements in feed efficiency may occur, among others through increased efficacy of exogenous enzymes. Even though stimulation of the gizzard through a coarse feed structure improves feed efficiency, it does not appear to affect the ability of the bird to handle intermittent feeding.