Good luck finding a commercial feed that is completely alfafa free. Our little guy wasn't allergic to alfalfa per se, but he couldn't eat anything with alfalfa in it due to the potassium content. Anything with more than minimal potassium in it would kill him...and it did, eventually. If we had known the entire story on his health (thanks to that vet for not telling us everything because he didn't want to hurt our feelings with the truth (spoken very snidely!)), we'd have known to do things differently.
Omolene 400 doesn't normally have alfalfa in it...normally. Since it's processed at the same plants as the other Omolene products, there is plenty of room for contamination - either by error or carelessness.
You might be better off mixing your own feed ration. It isn't all that hard. We used timothy pellets and beet pulp, along with flax meal. All of our horses have free choice hay - plain old bermuda grass/prairie hay.
Yes, I know - the beet pulp in our area has molasses in it - and molasses is high in potassium, but we didn't know at the time exactly what was wrong with our little guy.
Plain Old Dee, horses Dancer and Rain I believe in dragons, unicorns, good men and other mythical creatures!