A proper diet for your ferret will help promote good mental and physical health and the longest possible life span in captivity. A proper diet doesn't guarantee good health, but even in illness, a proper diet will likely lessen the length of time your ferret is sick, as well as lessen any lasting aftereffects.
Of course, one diet doesn't fit all ferrets. While you don't have to have a tailor-made diet for every ferret, there are different kinds of adult ferret diets, and you need to put your ferret on the appropriate adult diet. There are diets for sick, nursing, geriatric and younger ferrets. The list below is for healthy adult ferrets, any age except geriatric (starting at 4 to 5 years old), males and females. Still, there are variations even in the category of healthy ferrets described previously, so you will likely wish to tweak your ferret's diet to suit his individual preferences.
The major categories of nutrients for your ferret are fats and proteins. The correct types of fats and proteins will supply all the vitamins, amino acids, carbohydrates, fats, minerals and any other dietary factors your ferret needs. Although commercial ferret foods do contain some added carbohydrates, they are a minor component, and it has been suggested that enough fat in a ferret's diet eliminates the need for any added carbohydrates.
Ideally, the proper types of fats and proteins are poultry fat and animal protein. The percentages of each required in the diet are 20% to 22% for fat and 32% to 38% for protein. Poultry fat is better than beef fat because poultry fat has more unsaturated fat and less saturated fat. Animal protein is preferred over vegetable protein because a ferret's digestive tract is too short to digest vegetable protein. Animal protein should be among the first three (major) ingredients in whatever food you choose for your ferrets. The protein should be organ or tissue, not meat byproducts or meal.
Ferrets do not need and do not benefit from fiber in their diet, so do not give them lots of fruits or vegetables. Large quantities of fruits are also a bad idea for your ferret because of the carbohydrates, which can cause tooth decay. Give either fruits or vegetables only as treats and then sparingly. For example, one raisin, cut into 4 pieces, can be given over 1 to 2 days.
Don't give your ferrets any dairy products, chocolate, sugary foods or beverages, salty food, alcohol, caffeine, seeds or nuts.
Dietary deficiencies can cause health problems for your ferret. Correcting your ferret's feeding after your pet has lived on a deficient diet for months may not correct problems coming from the deficiency. Therefore, it's much better to make sure your ferret starts with a good diet. Dietary deficiencies and their possible consequences are listed below.