I have a question about the Columbian Exchange. What impact did 'Old World' animals have on the Americas?

The Old World animals had a tremendous affect on the Americas. One animal that had a tremendous impact was the horse. Horses made life significantly easier, as they were able to transport people and goods. Along with this, the Old World sent over cattle and pigs. These two animals would provide food for people in the Americas and continues to be a staple of our country to this day.