Where can you find information about cows breeding?

Visit your local county extension agent for information. A local agricultural college or college that has an agricultural program involving dairy and/or beef cattle is also a good place to visit to get breeding info on cattle. The internet is also a good place to go with, but be sure to make sure you are visiting good sites and not ones where you can't find where they got their info from.

Here's some good sites I found for you:

http://www.thebeefsite.com/articles/cat17/breeding-and-genetics

http://www.agric.gov.ab.ca/app21/infopage?cat1=Livestock&cat2=Beef

http://www1.foragebeef.ca/$foragebeef/frgebeef.nsf/all/ccf1007

That's just a start, as there is plenty of info at your disposal if you know what to look for.