Ferret Nutrition for Complete Newbies
where to start
ingredient quality
don't panic
Ferret Food FAQ
why feed a mix of foods?
Intermediate Topics
ferretone, oil treats, and vitamin A & D toxicity
why some cat foods are ferret-suitable
the wild polecat's diet
links to other ferret charts

Ferret Nutrition Basics:
A Crash Course for Complete Newbies

*the following is a combination of my advice/opinions and solid fact.  I've written it very simply and even given it silly illustrations it so that it's as easy to understand as possible (hopefully for all ages as well).  I encourage you to continue reading an learning from many sources :)

Jump to a Section:
Carnivores (understanding ferret history and body design)
Protein and Fat (looking for good stuff in ferret food)
Carbohydrates and Sugar (bad stuff that ferrets should avoid)
HOW to Pick Food that Avoids Carbohydrates

Carnivores (understanding ferret history and body design)

Ferret nutrition is pretty easy once you understand the most important basics: Ferrets are called "obligate carnivores". That means that:

1. they need meat to survive
2. they get all the nutrients they need from eating other animals
3. their body isn't built to digest anything that comes from a plant

Ferrets are domesticated from wild polecats, which evolved for ages eating mostly mice, voles, rabbits, and frogs.  They absolutely did not eat seeds, nuts, berries, fruits, or vegetables; they only ate other animals.  With such a long evolution on this diet, ferret bodies are designed to eat and digest meat only.

Ferrets also have a very short digestive tract compared to other animals. Food only stays in their system for 2-4 hours before it's out the other end, so they need to eat food that can be digested very quickly and easily.

Protein and Fat (looking for good stuff in ferret food)

So we know that ferrets need to be eating lots of meat, but how do we know which brands are the meatiest? Meat is made up of protein and fat. Protein and fat levels are always listed on a pet food's label, so these are the first things you want to look for when comparing foods for your ferret. A food with high protein and fat usually has a lot of meat in it.

No one has really done good research to decide on the exact minimum amounts of protein and fat that ferrets need, but here are a couple recommendations I've found in books and published papers:

-- 30% protein min & 15% fat min
-- 30% to 40% protein, 18% to 20% fat
-- 30%-35% protein, 15%-18% fat
-- no less than 34% protein, 20% fat

Notice that everyone's instructions are little different, since they don't have this down to an exact science.

In my opinion, the easiest rule of thumb is: Protein is good, fat is good. The more you can get the better.  I look for foods that list high amounts on their labels. I haven't found any ferret/cat food that I think is "too high" in protein or fat.

Carbohydrates and Sugar (bad stuff that ferrets should avoid)

Carbohydrates are not required by ferrets AT ALL, and the amount of carbohydrates they eat should be limited as much as possible. Some foods defend carbohydrates by saying that they're used to meet a pet's energy requirements. Ferrets can turn protein and fat into energy too, so they don't need carbohydrates for this.

It's a common opinion that feeding a ferret a food with a lot of carbohydrates will eventually cause pancreas tumors, called insulinoma.   Insulinoma is very serious and can cause a ferret to die earlier, need vet care or surgery, and have a less enjoyable life. Simple sugars are carbohydrates and are especially bad for ferrets.

HOW to Pick Food that Avoids Carbohydrates

So how do we figure out which foods are low in carbohydrates? Pet foods need to list their protein, fat, fiber, and moisture percentages on their labels (it's the law). They are not required to list their carbohydrate levels, so most brands don't.

There are 2 decent ways to try to make an estimate of the amount of carbs in a ferret food. I recommend using BOTH:

1. Look at the "guaranteed analysis" and do the math. Carbs are what's leftover after you've accounted for all the protein, fat, fiber, moisture, fiber, and vitamins/minerals in the food.  That means that if you keep looking for foods with high protein and fat levels, they will usually also be low in carbs.

Find a ferret food.  Take 100.  Subtract from that 100 the protein, fat, moisture, fibre, and ash listed on the label.  That will give you a rough estimate of the carbohydrate % in the food.
(Technically fiber is a type of carbohydrate, but what we're interested in what's missing on the label).

2.  Look at the ingredients list for the food. They are listed in order by weight. The first few ingredients make up most of the food, so focus on them.  Meats, fish, eggs, fats and oils will be made up of mostly protein and fat.   Fruits and vegetables will be made up of mostly carbohydrates.

Fruits are usually more sugary than vegetables, and there are also some concentrated simple sugar ingredients like 'cane molasses', 'honey', and 'raisin juice' that you should REALLY watch out for.

A final note about vegetable ingredients: there are no dry kibbles with 0 vegetables- Vegetable are usually needed to bind the meat together so that the kibble pieces keep their shape and form. Some brands also use a bunch of different of vegetables (in very tiny amounts) to meet their food's vitamin and mineral requirements.
Kibble can't be made using only meat, but if you choose well you can find something that is at least mostly meat.

Some References

Brown SA. Basic anatomy, physiology and husbandry. In: Hillyer EV, Quesenberry KE, editors. Ferrets, rabbits and rodents: clinical medicine and surgery. Philadelphia (PA): WB Saunders Co.; 1997. p. 313.

Bixler, H., Ellis, C.: 2004. Ferret care and husbandry. Veterinary Clinics Exotic Animal Practice. 7: 227255.

Bell, JA: 1999. Ferret Nutrition. Veterinary Clinics of North America: Exotic Animal Practice. 2(1): 169-192.

Schilling, K.: 2000. Ferrets for Dummies. Wiley Publishing, Inc.

Susan Brown, DVM: Rethinking The Ferret Diet. http://www.veterinarypartner.com/Content.plx?P=A&A=479

US Food and Drug Administration: Pet Food Labels - General. http://www.fda.gov/animalveterinary/resourcesforyou/ucm047113.htm

Nutrient Composition of Whole Vertebrate Prey (Excluding Fish) Fed in Zoos - http://www.nal.usda.gov/awic/zoo/WholePreyFinal02May29.pdf