Many pet parents struggle over what to feed their pets, particularly pocket pets and exotics, as education and diet selection for these special critters is often not readily available. Rabbits, for instance, have specific nutritional needs due to their unique anatomy and gastrointestinal (GI) physiology. As a result, whether or not to feed a pellet, hay or a combination diet is a common question faced by many rabbit owners.
Historically, it was common practice to feed rabbits an exclusive pellet-based diet. These diets, which tend to be low in fibre and high in starch and calories, were originally developed as food for production animals raised for their meat and fur, and not necessarily intended to live out their potential lifespan of five to fourteen years. Now that rabbits are being kept less as farm animals and more as household pets, nutrition has taken a different focus. Pellets continue to provide a level of convenience for the busy pet owner by making feeding time quick and easy, but do pellets really provide the best nutrition for your bunny? In order to determine an ideal meal plan for your rabbit, let’s begin by understanding the rabbit GI system and how it came to be.
The Inner Workings
Rabbits belong to the family Lagamorpha and are actually not rodents, as is commonly misconstrued. They are strict herbivores and have evolved to eat a diet exclusively of plant material. As a result, they are accustomed to ingesting large quantities of low-energy, high-fibre foods and actually require a diet rich in fibre to maintain gut motility and health. In the wild they are key prey species for many top predators and have developed several evolutionary strategies to keep themselves off the dinner menu. From a nutritional point of view, the most interesting adaptation is their unique digestive system and numerous gut microflora including bacteria and yeasts.
Rabbits possess a long GI tract relative to their body size, and this digestive system is capable of selectively controlling the retention and elimination of certain food items based on its particulate size and digestibility. The food that is easily digestible is kept within the cecum, which is a large, microbe-laden pouch located at the junction of the small and large intestines, while the indigestible bits are rapidly removed. Because rabbits lack enzymes to digest fibres, they rely on their partnership with a diverse population of microflora to break down these structural carbohydrates in their meal.
Some nutrients are absorbed directly through the cecum, classifying rabbits as “hind gut fermenters”. However, the majority of nutrients are hidden away within the gut microflora themselves and not readily available to the rabbit. To overcome this, the rabbit has evolved to acquire these nutrients through the production of two very unique stools. The first stool is the commonly sighted circular dry ball of fibre routinely cleaned from the litter box. The second is a large, green, soft stool that is rich in bacteria and covered in mucus and often referred to as a cecotroph, cecal or night stool. The cecotrophs are eaten directly from the anus as soon as they are produced and the pet parent rarely observes this nocturnal habit. Once ingested, the cecotrophs will travel through the stomach, protected from the stomach acid by the mucus covering, and into the small intestine where vitamins, minerals and essential amino acids can be absorbed. Utilizing this symbiotic relationship with their gut microflora, rabbits are able to produce their own protein, fat and vitamin supply from rather nutritionally unassuming foods.
To Pellet or Not to Pellet?
Understanding the balance between fibre and nutrition is paramount for keeping your rabbit’s GI tract motile and healthy. The most common mistake bunny owners make is not providing sufficient amounts of essential high-fibre foods. Over feeding pellets and foods high in calories can lead to obesity and/or lethal intestinal disease such as GI stasis and cecal compaction. While pellets do contain fibre, research has shown that the large indigestible fibre found in hay is more effective at moving through a rabbit’s GI tract than the ground fibre of pellets. The high-fibre content of hay makes it the most ideal diet for domestic rabbits and a fresh, continuous supply should be made available to your bunny each day. With this being said, your bunny’s diet should consist of 70% high quality high fiber grass hay, 20% high fiber uniform pellet, 5% fresh or dried greens, and 0-5% low sugar treats. Unlimited fresh, clean water, in multiple sources (water bottle and crock), should be also be available at all times.
(Veterinary nutritional evaluation and recommendations are part of our preventive health care for every pet’s visit to our hospital)