Timothy hay, which, along with fresh, clean water, should be made available to a guinea pig at all times, as this is the basis (approximately 80%) of their diet. Hay helps keep the guinea pig’s teeth short and their gastrointestinal tracts working efficiently.
In addition to hay, guinea pigs should eat 1/8 cup of guinea pig pellets every day. These provide the cavy with essential nutrients that they cannot get otherwise, such as vitamin C.
Guinea pigs should also eat somewhere between a handful and 1 cup of fresh fruits and vegetables each day. Some recommended veggies include: leafy greens like collard greens, kale, spinach, and parsley, as well as other vegetables such as green and red peppers, carrots, radish tops, and peas.
Vegetables to avoid include: iceberg lettuce, potatoes, cabbage, and broccoli. Guinea pigs should eat a few types of vegetables regularly and new veggies should be introduced into the diet gradually to avoid diarrhea, bloat, and an upset tummy.
Fruits should only comprise about 5% of the cavy’s daily dietary intake. About one slice of fruit a day is enough. Recommended fruits include: apples, strawberries, blueberries, grapes, and oranges.
Fruits and veggies should be fed to guinea pigs in small, bite-sized portions throughout the day (as opposed to all at once). Any produce not eaten after a few hours should be removed and replaced with fresh options.