Guinea Pigs make great pets. Here are some tips for feeding your Guinea Pig:

1. Provide your pet with commercially available pelleted chows for a majority of their diet (80%).
2. Do not feed rabbit pellets as a substitute for Guinea Pig pellets.
3. Provide your pet with Free-choice grass hay (such as Timothy or Bromegrass). This provides the fiber necessary to maintain normal intestinal tract function and promotes normal wear of guinea pig teeth.
4. Do not substitute alfalfa hay for grass hay. Alfalfa contains a high level of calcium, and excess calcium may lead to the formation of calcium bladder stones in guinea pigs.
5. Small amounts of fresh food (especially those high in vitamin C, like red and yellow bell pepper, leafy greens like spinach or kale, tomatoes, broccoli, kiwi fruit) can be offered daily. These foods should not make up more than 10-15% of the guinea pig’s diet, and should be washed to remove any chemical residues prior to feeding.
6. Do not overdo it on the veggies! Excessive consumption of fresh fruits and vegetables can cause diarrhea and bloating.
7. Avoid making radical changes in the type of food or water containers as well. Guinea pigs are creatures of habit, and don’t tolerate sudden changes in the presentation of their food or water, nor changes in the taste, odor, texture or form of the food itself.
8. Heavy ceramic crocks that don’t tip easily usually work best as food containers, and water is most easily made available by use of a water bottle equipped with a "sipper tube".
9. Check the sipper tube often. Guinea pigs tend to contaminate and clog their water bottles by chewing on the end of the sipper tube and "backwashing" food particles into it. For this reason, it is very important to clean and change the water container daily.

For more information, read the article on Vitamin C.