Firstly, the pellets you get from a pet store are not great. They contain mixes and seeds, which are not needed. Secondly, vegetable are a MUST. Without vegetables, guinea pig wouldn't be able to get their vitamin C. Follow this link to see what you can feed them
www.guinealynx.com/nutrition.html Fruits should only be given as a treat, but veggies should be given everyday. Dark, leafy vegetables are usually the best. Also, you need to feed your pig unlimited timothy or grass hay, preferably not from the pet store. Go to
www.guinealynx.com for the best info on general cavy care. Good luck!