Bioavailability of Nutrients for Animals

Abstract

Publisher Summary About 80% of the body's phosphorus is in the skeleton. The remaining 20% is contained in nucleotides, such as ATP, nucleic acids, phospholipids, and a host of other phosphorylated compounds needed for metabolism. Scheidler and Sell conducted research in which laying hens were fed varying concentrations of calcium, phosphorus, and phytate phosphorus in an attempt to determine the effect of phytase and calcium on phosphorus balance. Many studies have been conducted to determine the relative availability of different phosphorus sources for ruminants. Ammerman and colleagues fed wethers and steers low phosphorus hay and concentrate diet in a series of absorption trials and showed that calcium metaphosphate (50%) and calcium pyrophosphate (0%) provided less available phosphorus than monocalcium phosphate monohydrate (100%). The ratio of calcium to phosphorus has a large influence on the availability of phosphorus from a feedstuff. A major consideration with respect to phosphorus availability is the proportion of phosphorus in plant products in the form of phytic acid. It was suggested by the NRC that phosphorus in corn was 12% available to swine and that in soybean meal was 25%. Phosphorus bioavailability has been studied more extensively than most other elements since it is a much more costly item in commercial diet formulations. Phosphorus in many inorganic sources and in meat and fish meals is highly available to monogastric animals.