Hay should be available at all times for rabbits, guinea pigs and Chinchillas. Hay should be stored in a cool, dry area in an open bag to allow for good air circulation. Hay should have a fresh smell. Damp hay can become moldy and should be discarded. Rabbits, guinea pigs and chinchillas of any age can be introduced to hay without any special preparation.
The Importance of Hay in your small animal's diet!!
Rabbits & Guinea Pigs:
The most important part of the house rabbit diet is an unlimited supply of grass hay, which provides essential fiber as well as proteins, vitamins, minerals and carbohydrates. Because of the high fiber content of the hay, it is the best preventative for stomach and intestinal problems such as chronic soft stools. Hay (and greens) also provide some of the essential work needed to keep the teeth worn down due to all the chewing the rabbit needs to do to break it down. Guinea pigs are herbivores and require a similar diet as rabbits with plenty of grass hay and greens and limited commercial pellets. Hay should be provided for your pet in a box or hay rack and should always be available.
Chinchillas:
Chinchillas have a diet similar to rabbits. They are herbivores with continually growing teeth as in the rabbit and guinea pig. They originally came from a dry, cold mountainous area where their diet consisted primarily of tough dry grasses. Chinchillas should be provided with unlimited grass hay as described for the rabbit because the fiber is critically important to proper digestion and the tough hay strands may be helpful in keeping the teeth worn properly.