The addition of L. casei did not improve the stability of corn silage on exposure to air, although the LAB could inhibit the deamination during ensiling. The lower stability at 60 d than control silage could be due to the differences, although not significant, in lactic and acetic acid between the 2 silages. During deterioration, aerobic microorganisms may increase when high lactic acid remained to support their energy consumption, whereas the growth would decrease when acetic acid accumulated to exhibit its antimycotic property (McDonald et al., 1991).