The main staples of a guinea pig's diet include hay, pellets and water, but they may also eat various fresh fruits and vegetables. A balance of nutritious foods keeps the animal healthy and happy.
Guinea pig owners need to keep a fresh supply of water for the animal by replenishing it daily and as needed throughout the day. Grass-based pellets give guinea pigs a necessary supply of vitamin C and other nutrients. The nutrients deplete over time, so pet owners need to replenish the pellets each day. A 1/8 cup of pellets is all a guinea pig needs for one day. Overfeeding can cause obesity and other health problems. Supplement the pellets with fresh fruits and vegetables, such as raw carrots, apples, cucumbers, zucchini, coriander, dill and artichoke. A mixed variety of these foods benefits the animal's health and well-being.
Guinea pigs need a fresh hay supply each day to help with digestion. They require an unlimited supply continuously. Commercial treats can hinder a guinea pig's quality of life, due to the preservatives and fructose they usually contain. Rolled oats make a healthy treat that the animals enjoy. Multivitamins or salt wheels are not necessary if the guinea pig is receiving enough nutrients from a balanced diet.