breeding a holstein bull with a angus heafer

I wouldn't do it.

Typically you would want a calving ease bull or one from a breed not known for throwing big calves on a heifer. They aren't done growing yet and you really want to make that first baby as easy as possible on them.

Holsteins are rather large and you could end up with a dead calf...and a dead heifer.

Jena

I agree with Jena on this.

My Great-Uncle was a rancher. One year he bred a large bull to angus heifers. He had to pull several calves and never did that cross with a heifer again. The risk of loosing a cow while he was asleep was too great.

Yup, calving ease is the biggest problem. However, you should also be aware that dairy breed bulls usually have extremely nasty dispositions, and having one on your farm is like playing with fire.