Feeding a heifer Purina Evolution Juvenile Horse Ration?

We have a couple left over bags from our horses that we got rid of and the calves go crazy for it when we feed them small amounts as a treat. There are no warnings about not feeding it to cattle. It has Min 15% protein, min 7% fat min 15% fiber and selenium @ 0.45mg/kg.
I hate to waste the extras and I feel that if we fed our next year's show heifer (March 30, 2014 & 562lbs as of today) on it that she would do well but i'm worried about giving it to her as its not technically meant for cattle.
Anyone that is more experienced have any input?

I don't know about the specific feed that you have but how many bags of sweet feed have been sold for horses and cattle? I don't see why it would be a problem, the only thing I would even question would be the selenium. I don't know how many bags you have but the least you could do is mix it with your regular feed or use it as a top dress.