A Review on Calcium to Phosphorus Ratio in Swine Nutrition

The metabolisms of calcium (Ca) and phosphorus (P), including other minerals and nutrients are highly dependent on the dietary ratio of Ca to P. Wider ratios between Ca and P lead to antagonisms between Ca and P resulting in inefficiencies of nutrients absorptions and consequently results in high levels of dietary Ca, P and other nutrients in the pig manure that triggers eutrophication. One of the major reasons responsible for this is because dietary source of Ca is relatively cheaper compared to that of P. Later, due to the essential physiological functions of P, the concept of P insurance policy in the diet was introduced by adding more P in the diet as well as more Ca to avoid P deficiency. P insurance policy did not provide the expected results, again because further widening of the ratio of Ca to P. This stimulated about 151 independentstudies tailored to identifying the proper dietary Ca to Pratio as to enhance their metabolisms as well as other dietary nutrients. The Ca to P ratio in the bone is about 2: 1. It was thus recommended that Ca to P ratio in the diet should be 2: 1. Later reviews on the role of Ca and P revealed the fallacy of thinking that the ratio of Ca and P in bone is the ratio that should be used in feed formulation. The Ca to P ratio varies from 0.6 to 1.2: 1 in the sow’s milk and was also thought to be the optimal ratio in the diet.This was later found to be fallacious. At present, it has been found that the dietary ratio of Ca to P for optimal performance as well as reduction in eutrophication is 1: 1.