A way to add additional farm animals could be...

A petting zoo would be neat. There could be clowns, balloons, cotton candy machine, snow cone machine, and animals to visit. Also, if you want some of your own, you can buy them. Pig pens, goats, sheep, bringing back of reptile/bird cages, ect. Better aquariums that more fish can be added to and the huge one that sims can get in from Sims1.