Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

Calcium (Ca) and phosphorus (P) are the most abundant minerals in the pig and are involved in lean tissue deposition and synthesis and maintenance of the skeletal structure. Swine diets are typically formulated with low margins of safety for P and excess P in the diet can lead to increased P excretion, which can result in negative environmental effects. To have an adequate utilization of both Ca and P, it is important to consider the Ca:P ratio when formulating pig diets. Research has shown that a wide Ca:P is detrimental to pig growth performance and bone mineralization when diets are low in STTD P. Therefore, the objective of this study was to evaluate the impact of varying Ca:P ratios fed at two levels of STTD P:NE on growth performance, bone, and carcass characteristics of pigs from 12 to 129 kg. When P levels were below requirement estimates, widening the Ca:P ratio from 0.90:1 to 1.75:1 reduced growth performance and bone mineralization; however, widening the Ca:P ratio improved performance and bone mineralization when P levels of the diet were above requirement estimates.