Rashba"g says in the mishna, if a person separates his 3 animals for nezirus, then they automatically become chatos olah and oshom. Rosh explains that each korbon is only suitable for it's own designation. The chatos is only the female. The shelomim is only an ayil. And the olah is only the keves. But why is the olah only a keves. Why isn't the ayil also suitable for the olah. Now, I grant you, that it may be possible to define the olah by process of elimination. Because the shelomim and the chatos are very specific. However, how can the Rosh say that the olah must be a keves, not an ayil?

Avrumi hersh, London england