Hay is actually supposed to make up the bulk of a guinea pig’s diet, so try to keep it interesting. There are different types to choose from, including timothy hay, oat grass, and orchard grass. Use a hay rack instead of placing it near the bedding.
The last thing you want is your guinea pig accidentally ingesting some of his bedding with the food and getting sick. Make sure you leave fresh hay in the rack every day and try to keep it at least ¾ full.