Physico - chemical chyme conditions and mineral absorption in broilers

In the Netherlands the efficiency of mineral absorption from the gastrointestinal tract of farm animals is a topic of interest to reduce the mineral concentration in animal manure. This study was done with broilers. It was focused on physico-chemical chyme conditions. These conditions were related to the absorption of minerals. Carboxy methyl cellulose was used as a model substance to affect the intestinal viscosities. Retention time parameters, pH and osmolalities were recorded. The site of mineral (Na, K, Ca, P, and Mg) absorption and apparent absorption values up to successive gastrointestinal segments were determined. Effects of the intestinal viscosity were verified using wheat-based broiler diets.

Dietary inclusion of carboxy methyl cellulose (up to 1%) increased the intestinal viscosity, the mean retention time and decreased the ileal pH. The absorption of small osmo-active chyme components was reduced, which was reflected in less variable osmolalities as the chyme moved from the proximal small intestine onwards. The main site of mineral absorption is between the duodenum and the lower jejunum. In these segments the absorption is negatively affected by the inclusion of carboxy methyl cellulose in the diet. It was discussed that the intestinal viscosity was the main cause for this reduction in mineral absorption. Negative effects were partially compensated in the ileum. Similar effects were shown in wheat-based diets, but effects were less pronounced.