Comparative effects of three phytases on phosphorus and calcium digestibility in the growing pig

Phytase addition to swine diets has generally resulted in a marked increase in phosphorus (P) digestibility and in a reduction of faecal excretion of P. The number of phytases present in the market is growing and the origins of the microbial genes are becoming more diversified. The aim of this study was to compare the effects of 3 different phytases on P and calcium (Ca) digestibility in pigs. The control diet was based on soybean meal, maize and barley. The inclusion levels were 250 (Q 1) and 500 U/kg (Q2) for an E. coli phytase (Quantum), 500 U/kg (Nat) for A. niger (Natuphos) and 750 U/kg (Ron) for P lycii (Ronozyme P). All phytases significantly reduced faecal concentration of P. For Q2 this reduction was significantly higher than for Q1. P digestibility was improved by 13.8, 18.6, 18.3 and 17.9 percentage units by Q1, Q2, Nat and Ron respectively. The P equivalencies, considered as supplemental P digested compared to the non-supplemented diet of Q 1, Q2, Nat and Ron were 0.492, 0.732, 0.678 and 0.678 g of available P/kg of feed respectively. Ca digestibility was also significantly improved by the phytases. It can be concluded that the 3 phytase preparations improved the digestibility and the apparent absorption of P and Ca in the growing pig fed a diet containing P exclusively from plant origin. The effect of including 500 U/kg of E. coli phytase on P digestibility was similar to those induced by the A. niger and R lycii phytases at their recommended levels of 500 and 750 U/kg, respectively. (c) 2007 Elsevier B.V. All rights reserved.