[davisfh]

No problem. I'd doubt a comment like that myself. Take a look here (you may have to copy and paste):

http://www.horseforum.com/horse-breeding/mule-reproduction-47843/

There seems to be a problem with disparate numbers of chromosomes between horses and mules, but apparently, this problem is "sidetracked" from time to time.

The question is posed at top of page and you'll have to cursor down about half a page to see the answer.

[DManA]

Thanks, I’ll look at it. These issues are not simple.