Comparative effects of three phytases on the phosphorus and calcium use in the weaned piglet

The addition of phytase to swine diets has generally increased P digestibility and consequently reduced fecal excretion of P. The comparative effects on P and Ca digestibility of dietary inclusion of 5 different phytases were evaluated in the weaned piglet. RONOZYME HiPhos is a microbial 6-phytase produced by synthetic genes, mimicking a gene from Citrobacter braakii, and was compared to the Escherichia coli-derived phytases Phyzyme and OptiPhos. In total, 112 weaned piglets (28 d old) were allocated to 8 equal groups of 14 animals. Pigs were fed for 29 d a vegetable-based diet without addition of mineral P [Co(-)] or this diet supplemented with 12 g/kg feed of CaHPO(4) [Co(+)] or with HiPhos at 1000 units/kg (H1000) or 1500 units/kg (H1500), Phyzyme at 500 units/kg (P500) or 750 units/kg (P750), or OptiPhos at 500 units/kg (O500) or 750 units/kg (O750). All phytases reduced (P < 0.05) fecal P concentration and excretion and increased (P < 0.05) P digestibility and apparent P absorption. The digestible P equivalences of H1000, H1500, P500, P750, O500, and O750 were 0.94, 1.50, 0.67, 0.92, 0.58, and 1.11 g of full available P/kg of feed, respectively. Calcium digestibility was increased (P < 0.05) and Ca excretion reduced (P < 0.05) by the phytases. The 3 phytase preparations increased digestibility and apparent absorption of P and Ca in weaned piglets fed a diet containing P exclusively from plant origin.