I usually introduce a few common farm animals after talking about pets.
el caballo – horse
la vaca – cow
el cerdo – pig
la oveja – sheep
el pato – duck
After you have introduced the words, use them as you play with your child. Repetition over time is important for real learning. Point out animals in books and videos, and try these activities.
Using small toy animals or pictures of animals, hide both hands behind your back with one of the animals in one hand – el caballo, for example. Ask your child ¿Dónde está el caballo? When your child guesses which hand the horse is in, say ¡Sí, es el caballo!, or No, no hay nada. (There is nothing there). When your child guesses correctly, try it with another animal.
Print farm scenes to color with your child, like this one, or play with stickers like these to make a farm scene. As you color or make the scene, repeat the words for the animals, and point out the body parts that your child knows too.