The ATTD of P in the corn–SBM diets observed in this experiment is in agreement with published values (Stein et al., 2008). The decreased fecal P excretion and increased P absorption and digestibility that was observed as OMM was added to the corn–SBM diet indicate that supplementation with OMM may improve the efficiency of P absorption. The likely reason for this observation is that OMM may reduce the formation of complexes between P and other minerals, such as Zn and Ca, and, therefore, increase P absorption in the small intestine. Another possible reason is that the HMTBa released
from the organic minerals may increase phytate P utilization as reported by Liem et al. (2008), although the
mechanism is not clear. Compared with corn–SBM diets, the increased ATTD of P in the corn grits diets is mainly
due to the reduced level of phytic acid in these diets.