Purina Farms is located about an hour out of the southwest side of St Louis, MO. There's not a whole lot to it, honestly, but it's free, which is a major plus in our book. Also you can do everything in just a couple hours.
Exhibits include a mini-museum to the history of Purina and a spinning-ball demo of how their animal chows are made. The kids weren't that enthralled, but they liked the brief movie that came after. You exit into the upper barn where there's a play area for both big and little kids. They can pedal tractors, swing in a hayloft, and climb through some tubes. In the lower level, you can come face-to-face with cows, horses, and pigs. A special petting section always has a couple piglets and bunnies and young chickens out. Grandparents and the girls arrived early enough to get to milk cows (the last milking is at 12:30).
We couldn't even out pull a sled dog!
Next to the dog arena is the pet rescue center which is mostly dogs and cats. The cats live in a fenced, 3 story "house" filled with toys and made completely out of the things cats love best- carpet covered stairs, windows, and banisters. If they want some human loving, they'll come up to the nylon net. Otherwise, they just lay around looking regally content.
The "hayride" was kind of a big so-what, but the kids liked riding in a wagon behind a tractor. It's probably more fun in the fall or during seasonal themed events or pet adoption days.