Pigs experiencing a moderate and a high level of antigen exposure were self-fed one of six dietary concentrations (.30, .40, .50, .60, .70, .80%) of available phosphorus (AP) from 14 to 60 pounds body weight. Pigs reared via a management scheme that resulted in a moderate level of antigen exposure consumed more feed daily, gained body weight faster, required less feed per unit of gain, and accrued more body protein daily than pigs reared in a high antigen exposure environment. Over the duration of the study, dietary AP concentrations of .6 to .7% and .4 to .5% in the moderate and high antigen exposure pigs, respectively, were needed to maximize daily body weight gains, gain:feed ratios, and body protein deposition.

Based on these data, the dietary available phosphorus needs expressed as a percentage of the diet for 14 to 60 pound pigs experiencing a moderate or high level of antigen exposure are about 2.4 and 1.7 times greater, respectively, than current NRC (1988) estimates.