Effect of High Available Phosphorus Corn and Elevated Fat and Protein Corn on Nutrient Digestibility and Excretion in Finishing Pigs

Purdue University 2002 Swine Research Report. Typical corn and soybean meal diets fed to pigs in the US are known to contain as much as 80% of their phosphorus content in a form that is unavailable to the pig (NRC, 1998). Therefore, the phosphorus nutrient requirement has historically been met by inorganic phosphorus supplementation in the diet, often in excess of dietary requirements. Excess dietary phosphorus is excreted in the feces and urine of the pig. This can lead to increased nutrient accumulation in the environment as manure is utilized as a nutrient source for crop production. There have been several dietary manipulations studied in an attempt to achieve greater nutrient digestibility by the pig and prevent excess nutrient excretion. One attempt at reducing phosphorus excretion has been genetically selecting corn to contain less phytic acid phosphorus. Two mutant corn genes, Lpa-1 and Lpa-2, have been identified and used to create corn varieties reported to contain 66% and 33% reductions in phytic acid phosphorus, respectively (Raboy and Gerbasi, 1996). These corn varieties have been reported to increase the bioavialability of phosphorus to the pig approximately 54% (Spencer et al., 1998). Similar genetic selections have been made to increase the protein and energy content of corn. Recently, an elevated fat and protein corn has been developed and has been combined with the low phytic acid gene to create an elevated fat and protein corn with high available phosphorus content. The objective of this study was to determine the nutrient digestibility of four genetically enhanced corns when fed to finishing pigs.