Moo Moo Woes from the inexperienced

I have a bottle-fed heifer that's 12-13 months old. She was in dad's pasture with two of my steers (and about 150 head of sheep); 22 days ago, she got out and went gallivanting. Found her about 4 days later in the neighbor's pasture which is about 3 miles away. I decided to take her to my pasture; when I kicked her out of the stock trailer, my heifer rode her briefly---so she was in heat for the first time.
Today, I got home from work and she was not here; she had last been seen here about 10 am. I located her 6-7 miles away at a neighbor's.

Is she too young to breed to a low birth-weight bull?

If she is too young to breed, is there anything I can do besides put a yoke on her to keep her in?

I can't have her getting out every time she comes in heat. If it matters, the heifer is a brown swiss

I've got lucky twice now with finding her back, but my luck can't hold forever.

 

73, Mark

Moo Moo Woes from the inexperienced