Digestion and Absorption of Dietary Phosphorus in Fish

The absorption of dietary phosphorus typically begins with the digestive phase, where various chemical processes take place. These include the solubilization of calcium phosphates by gastric acid in the stomach, as well as the enzymatic breakdown of various organic phosphorus compounds within the intestinal lumen. Enhancing the digestive phase can be achieved by pre-digesting diets or designing them to be readily digestible, which can be especially advantageous for fish with limited digestive capabilities. This improvement may involve supplementing the diets with phytase and organic acids, fermenting feed ingredients, and selecting highly digestible ingredients. Following the digestive phase, solubilized inorganic phosphates and small organic phosphates are absorbed across the intestinal epithelium. This absorptive process is governed by numerous bodily mechanisms that are not easily altered or enhanced. Nonetheless, comprehending these absorptive mechanisms of dietary phosphorus may pave the way for the development of novel methods to increase dietary phosphorus absorption.