Written by Laura Atkins and Susan Smith Ph.D.

Function

Bunnies cannot make their own vitamins
The structure of each vitamin is different, however, all are organic molecules found in trace amounts in bacteria or plants. They can be divided into two general groups.
- Water soluble vitamins (B-complex, C)
- Fat soluble vitamins (A, D, E, K)

The water soluble vitamins and vitamin K are synthesized by the cecal bacteria and obtained by coprophagy.
Carotenes (plant pigments) are converted to Vitamin A in animal tissues.
Pre-vitamin D is found in sun-dried alfalfa hay and can be synthesized by the skin after exposure to UV light.
Vitamin E is found in vegetable oils and cereal grains.

Rabbits do have an absolute requirement for all the vitamins except C.
However, the vitamin K and the B-vitamins are provided by the cecal bacteria and therefore may not need further supplementation until the cecum is disturbed or the cecal pellets are not consumed.
Rabbits receiving pellets as part of the diet should be receiving sufficient amounts of vitamins D, A, and E. For rabbits receiving no pellets, it is possible that D and E would become deficient after a long time (many years). Carrots, of course, are rich in vitamin A.

Mature house rabbits and Angoras: Normally should not need any vitamin supplements.
Older Rabbits: If they have difficulty re-ingesting cecal pellets, then B-vitamin supplements maybe appropriate.
Sick rabbits: May have the same B-vitamin requirement as older rabbits especially if the GI tract is disturbed or cecal pellets are not being eaten. Many people have reported appetite stimulation after injection with B-complex vitamins.
Growing rabbits: Liver stores and pellet sources of vitamins should be sufficient to support growth.