Sure it's possible. I have experience replacing 25% of Corn in the concentrate saving some money.
To change, is important to see Quality and Price.
In dairy cows I had replaced 60% of corn in the concentrate. The change was successfully . No problems with cows and great saving. (Broken rice price was 0.65 to 0.7 of corn price).
Yes, but remember that a good concentrate for calves must have about 17-18% of protein STQ! The energy is not so important in this period. Is important to feed with a concentrate a soon as possible.