Such pH values are usually reached during lactic acid fermentation. Lactic acid bacteria metabolize plant based carbohydrates accompanied by acidification, that activates endogenous phytases and degrade phytic acid (De Angelis, 2003). The CTTADof P in the feeding group receiving native bran does not differ from the group receiving extruded bran. Similar results couldbe observed for Ca digestibility, whereby the differences among the bran variants were even more pronounced than for P digestibility. The CTTAD of Ca was highest with the fermented bran feeding diet and even significantly lower in the diet fed with extruded bran, compared to native wheat bran. The inhibitory effect of phytic acid on Ca absorption was explained asa result of complexation of Ca by phytate (McCance and Widdowson, 1942a,b). The high temperatures applied during the extrusion process obviously degraded the endogenous phytases of the bran. Even at a lower temperature of 90◦C, Blaabjer get al. (2010) discovered reduced digestibility of P and Ca due to the inactivation of plant phytases of wheat and barley