Hereford World magazine had a cover article on "Heterosis and the Baldie Female' that might help you in the October issue. http://www.herefordworld.org/tailored.aspx
I can't figure out how to reach the article online; but you might be able to figure it out. You probably will have to contact 'Hereford World' if you don't have a copy available. I am sure 'Hereford World' has other better Baldie articles in the archives too.