Phosphorus is an important part of a pigs growth regime. It is also one of the most expensive nutrients in a pigs diet, behind energy and protein. When a pig ingests phosphorus there is a variable amount that becomes soluble and is used for growth while some phosphorus is excreted and essentially wasted. An understanding of what causes phosphorus to be utilized is important to understand to increase efficiency in pig growth and feed costs. This paper describes designed mathematical models that simulate what happens to dietary phosphorus in a pigs digestive system especially focusing on how calcium and phytase effect phosphorus digestibility. The models look at three parts of the pigs digestive tract, stomach, proximal small intestine, and distal small intestine. Parameters for the model were taken from past literature. A sensitivity analysis was done to prove the effectiveness of the model. The model was able to accurately predict the efficiency of phytase and a decrease in plant phytase efficiency compared to microbial phytase. The predictability of the model was proven when results were compared with published pig data not used for model development. Prediction of phosphorus digestibility across 66 experiments and 281 observations was adequate. Prediction of calcium was not as accurate. This model proved useful in evaluating phosphrus digestibility for different feedstuffs and feeding strategies. It can also be used for improving dietary phosphorus utilization by quantifying the variations effecting phosphorus utilization.

To read this article visit: http://jas.fass.org/content/89/11/3596