Chinchillas have very sensitive digestive systems, so feeding a good quality diet appropriate for chinchillas is essential to their health. In the wild, chinchillas are naturally adapted to eating a diet of vegetation that is high in roughage. They are not designed for rich or fatty diets and such diets can easily cause serious digestive upsets. Instead, feed your chinchilla quality chinchilla pellets supplemented with plenty of fresh grass hay.
Pelleted diets are better than a mixture of loose items. Loose mixes may be nutritionally balanced while in the bag but only if your chinchilla eats all of the parts of the mix.
Look for a pelleted, formulated diet specifically for chinchillas that is 16-20 percent protein, low in fat (2-5 percent), and high in fiber (15-35 percent). If it is impossible for you to get a good quality chinchilla diet, many experts suggest substituting a good rabbit or guinea pig pellet with similar characteristics but this should only be done temporarily and in emergency situations. Online stores should be utilized if your local pet store does not carry a quality chinchilla formula. Chinchillas have specific dietary requirements that are different than other rodents and their health will suffer if they are not fed quality, chinchilla-specific food.
If you choose to feed a loose item mixture (with pellets, seeds, corn etc.), keep in mind that there is a concern that feeding corn can cause digestive upset and bloating, and many chinchilla foods contain corn as an ingredient. Since corn is starchy and likely largely indigestible for chinchillas, whole corn should be avoided as a treat or the main part of a diet. Scientifically speaking, however, little is understood about the ideal chinchilla diet beyond the need for lots of roughage.
Most chinchillas will eat one to two tablespoons of pellets a day. While they are not prone to overeating, for freshness it is a good idea to feed a small number of pellets at a time. Feeding a tablespoon in the morning and again in the evening seems to work well, but can be adjusted as needed. Some people just feed a couple of tablespoons in the evening.
Try to be consistent with whatever you choose to do, as chinchillas like routine. A small food hopper or heavy ceramic dish is the best way to keep the food from getting dumped or soiled.
Even when you choose a high fiber pelleted diet, it must still be supplemented with hay to ensure your chinchilla gets plenty of roughage (fiber). This roughage in hay helps keep chinchillas' teeth in good condition and the digestive system functioning properly. Feed as much good quality grass hay (orchard grass, Timothy-grass, etc.) as your chinchilla wants each day. Hay should be cleaned out and fed fresh on a daily basis to keep it from becoming soiled or moldy. Pressed cubes of hay can be given, but it is recommended to still feed loose hay, as it has long strand fiber.
Alfalfa hay should not be fed exclusively to most adult chinchillas. Alfalfa is high in protein, calcium, and oxalates which means that too much could possibly lead to urinary and other problems. Don't feed any hay that is damp, smells musty, or is discolored regardless of what kind it is.
Chinchillas should be given very little in the way of treats—never more than a teaspoon a day. Raisins and dried fruit are favorites but are also high in sugar so they should be fed in very small quantities and infrequently. Try not to feed more than 3 or 4 raisins per week. Rose hips are another recommended treat as they are high in vitamin C and other nutrients. Most commercial treats for chinchillas will be too high in sugar and fat and are best avoided. Check with your vet if you are unsure about anything you are feeding your chinchilla.
Though we don't normally think of twigs and branches as anything special, your chinchilla will likely view them as a terrific treat. Twigs from apple trees and other safe trees can be given to your chinchilla. Make sure any wood you use has not been treated with pesticides and do not offer branches from toxic trees, including trees that have fruit with pits or stones, evergreen wood, and others.