Iyayi , E. A. Effect of Phytase Supplementation on the Digestibility of Crude Protein, Amino Acids and Phosphorus of Cowpea (Vignia Unguiculata) in Broilers. Int. J. Poult. Sci. 2012, 12 (1), 45–50. https://doi.org/10.3923/ijps.2013.45.50.