ADDITION OF MICROBIAL PHYTASE TO DIETS OF YOUNG-PIGS

Microbial phytase was added at concentrations of 0, 500, and 1,000 phy tase units per gram (PU/g) to a diet that derived the majority of its phosphorus content from organic sources. In addition, a positive contr ol diet was prepared by adding calcium phosphate to increase the total dietary phosphorus by 1.7 g/kg. Each diet was available ad libitum fo r 3 wk to nine individually penned pigs approximately 5 wk old and wit h an initial weight of 10.2 kg. Digestibility of phosphorus was estima ted, using chromic oxide as an indicator, from fecal samples obtained during the 3rd wk of the trial. Blood serum and metatarsal bones were obtained at slaughter. The addition of the microbial enzyme resulted i n increased rate and efficiency of gain, increased digestibility of di etary phosphorus, increased serum phosphorus, decreased serum alkaline phosphatase, and increased metatarsal ash and weight of metatarsal ph osphorus. The response to dietary microbial phytase was similar to tha t resulting from feeding a diet containing 1.7 g/kg of additional phos phorus from calcium phosphate.