As long as you have enough neighbors or farm cash you can purchase dairy farms to store your cows. Dairy farms hold up to 20 cows (or 19 cows and 1 bull) each, and you can buy as many as you want.
[header] How to guide animals in farmville [title] Focus on raising animals that take up the least amount of space. [step] Consider that on your farm, space is always at a premium. This list includes the obvious smaller animals, like ducks and bunnies, but also a couple of unexpected others.