Hay is an integral part of a healthy diet for rabbits and guinea pigs. Many people find it strange, as hay appears coarse and unappetizing to us. The importance of hay goes back to evolutionary times when rabbits and guinea pigs as a species were gradually adapting to their environments.
Rabbits and guinea pigs are herbivores, or more accurately, fibervores. They have evolved over millions of years to not only survive, but thrive on a diet consisting of coarse grasses and shrubs. In contrast, humans as a species have evolved to require a much more calorie-dense diet, and we do not have the internal machinery to process and extract nutrition from a tough, fibrous diet.
Rabbits and guinea pigs have aradicular hypsodont teeth, which means that their teeth have an open root that allows the tooth to constantly grow and erupt throughout the animal’s life. This is important for them as the silicates in grasses produce a lot of tooth wear, and without constant growth, their teeth would wear away and leave them unable to eat.
In a pampered domestic home, our pet rabbits and guinea pigs are not limited to the coarse forages that their ancestors had, and are often quite spoilt with dietary choice and quality. However, their teeth remain the same as their wild ancestors, and still require an adequate amount of wear to maintain healthy occlusion. As a result, rabbits and guinea pigs should have a diet that consists of at least 80% hay, and hay should be available for them at all times.
It is important that rabbits and guinea pigs are not allowed to choose to eat other foods in preference to hay. For example, if hay is always available, but so are palatable, energy dense pellets, the average rabbit or guinea pig will always choose to eat the pellets over the hay, and may not eat enough hay even though it is readily available. I liken it to offering a child an unlimited supply of salad greens versus an unlimited supply of M&Ms or potato chips - the salad is most likely going to be ignored!
An appropriate diet for a rabbit or guinea pig consists of 80-90% hay, 10-20% green leafy vegetables, and 5-10% pellets and treats. It is important for guinea pigs to receive a daily portion of fresh vegetables as they require dietary vitamin C. Good vegetables to feed include bok choy, kai lan, choy sum, silverbeet, kale, parsley, chicory, celery leaves, and rocket. I generally recommend cruciferous vegetables such as cabbage, broccoli, and brussel sprouts to be fed in small amounts or avoided due to the higher carbohydrate contents of these vegetables.
A tablespoon of pellets per animal per day is a good amount. It sounds like a piddly amount, but it is equivalent to 450g of rice, bread, or oatmeal for a 65 kg person. You can scatter pellets around your pet’s living area to make it last a bit longer, or feed pellets and treats in food puzzle toys to add enrichment and a little exercise to their daily routine.
I’m planning to do a few more blog posts on diet in rabbits and guinea pigs, and the next post will be about different types of hays and what each type is suitable for. Drop me an email at nicolex.su@gmail.com if you have any questions or requests for post subjects!