Boggy's got it right. Also, if you have more than one heifer, they'll ride each other when in heat. That affects performance some. You can get a feed additive (MGA?) that is supposed to keep them from cycling.
I don't know how the auction mixed them up but I got one heifer in a possumbelly full of steers. That poor girl stood with her ass in the corner until I could get rid of her.
Once in the freezer, good eats,just like miles said.
Dale