Phosphorus Availability Increased by Phytase

Researchers at the University of Georgia fed mixed sex broiler chicks a corn-soybean meal experimental diet containing 22.2 percent crude protein, 0.88 percent calcium, 0.46 percent total phosphorus and 0.272 percent phytate phosphorus. The phosphorus-deficient diet contained a calculated metabolizable energy level of 3123 kcal/kg. Phytase levels of 0, 93.75, 187.5, 350, 750, 1,500, 3,000, 6,000, and 12,000 U/kg diet were added to the corn-soybean experimental basal diet. A positive control diet containing 0.70 percent total phosphorus was included in the experiment. Supplementing phytase from 0 to 12,000 U/kg significantly increased body weight gain, feed intake, feed efficiency, plasma phosphorus, tibia ash, tibia ash weight, total phosphorus retention, phytate phosphorus disappearance, apparent nitrogen retention, the apparent metabolizable energy (corrected for nitrogen) content of the diet and reduced rickets in the chicks fed the experimental diets. Regression analyses were used to help explain the treatment effects. These results indicate that broilers consuming a total phosphorus deficient corn-soybean meal can achieve maximum performance when phytase is supplemented at the rate of 12,000 U/kg diet.

Shirley, R.B. and H.M. Harms, Jr. 2003. Graded levels of phytase past industry standards improve broiler performance. Poultry Sci. 82(4):671-680.