In this study, the difference between the soluble protein content of the dry corn and REC was possibly a consequence of fermentation process of REC and it may also have contributed for the increase in starch digestibility. The increase of soluble protein content over the time of ensiling has been also reported for rehydrated corn(Ferraretto et al., 2015) and HMC(Kung et al., 2014). Moreover, the soluble protein content was highly associated with increased in vitro digestibility of starch(Kung et al., 2014; Ferraretto et al., 2014), indicating that the solubilization of the protein corn matrix may increase the access of ruminal bacteria on the starch granules