The dietary phosphorus requirement of young pigs is not well established. Values of a net requirement estimated by the ARC (1981) extend from 2.7 g/day for 5kg pigs to 4.6 g/day for 25kg pigs but current literature suggests that the actual requirement may be lower than this. Although maximum bone mineralization is not necessary for optimum growth, later bone development should not be impaired by a deficiency of phosphorus.

Use of phytase in piglet diets has resulted in increased rate and efficiency of gain (Beers and Jongbloed,1992) and increased metatarsal phosphorus (Young et al, 1993). The enzyme hydrolyzes phytate, releasing phosphorus into the gut, and could thus be used in place of expensive inorganic phosphates. Quantification of phytase/phosphorus substitution is as yet undetermined. Therefore this experiment was conducted to look at the phosphorus requirement for growth and bone development and to assess the effect of phytase on dietary phosphorus requirement.