I was thinking about your original question, where you asked what nutrients ferrets need.
I thought it might be helpful for you to have a basic primer:
Protein:
Ferrets are designed to handle meat based proteins.
The primary protein source for a ferret (and the first ingredient on the label) should be meat. The Forum recommends at least three protein sources as a minimum
Protein is made up of amino acids, and approximately 24 amino acids are found in animal tissue. Ferrets require a high protein level. This is higher than requirements for cats and dogs. The protein must be high-quality, meat-based protein to meet their requirements for the essential amino acids.
The amino acids methionine and cystine are also important for good health. These two amino acids contain sulfur. When they are digested, the sulfur is converted to sulfuric acid. The sulfuric acid is eliminated through the kidneys and into the urine. This acidifies the urine and prevents bladder infections and struvite bladder stones.
Protein from plants such as corn gluten, wheat gluten, soybean meal and soy protein isolates do not contain these sulfur-containing amino acids. Diets high in plant-based protein will raise the pH of the urine, which can cause struvite bladder stones.
Fats:
Fat Requirements
Ferrets also need a high fat (18%-22%) diet which allows them to digest the proteins and provides for their energy needs. Fat is a concentrated source of energy and provides vitamins A, D, E, and K. Chicken or poultry fat should be the second or third ingredient in the list. Fish oils are good sources of Omega-3 dietary fatty acid, which is good for your ferret (it helps with allergies, itchy skin, arthritis, heart disease, and renal failure). However, fish oil may cause the food to have an undesirable odor or be unpalatable to ferrets. Mine love Cod and fish should be freshwater fish, like smelt.
Fat is important in the ferret diet for several reasons. Fat contains 2.25 times the energy of protein or carbohydrates, so it is a highly concentrated source of energy for ferrets. Fat also contains the essential fatty acids linoleic, linolenic and arachidonic. These fatty acids are needed for normal skin and hair coat.
Fat also contains the fat-soluble vitamins A, D, E and K.
Vitamin-A deficiency can cause stunted growth, night blindness and muscular incoordination of the rear legs. Vitamin-D deficiency can cause abnormal bone development.
Vitamin-E deficiency can cause anemia, anorexia, a weak immune system, an impaired gait and paralysis. Vitamin-K deficiency can create problems with blood clots that can lead to bleeding problems.
Taurine:
Taurine is thought to be an important supplement for vision. Taurine is an essential amino acid, along with lysine and methionine. Deficiencies in these important ingredients could cause blindness or heart problems. Plant proteins are very low in taurine, so look for added taurine and meat ingredients. 500 mg per day per ferret is recommended
Ferrets have a short intestinal tract. They also have a rapid transit-time through the intestines. It usually takes only three to four hours for food to go from the mouth to the litter box. This makes the ferret’s digestive tract inefficient. To make things even worse, ferrets have a simple gut flora, minimal brush border enzymes and lack a cecum. This means ferrets cannot digest fiber, starch or other complex carbohydrates. To make up for this inefficient digestive tract, ferrets need a diet with a high level of protein, a high level of fat, a very low level of fiber, and a very low level of carbohydrates.
Calcium:
Minerals are also crucial for proper ferret nutrition. Calcium and phosphorus are the two minerals that cause the most problems. Meat contains a lot of phosphorus and very little calcium. Ferrets actually need slightly more calcium than phosphorus. If calcium is not added to the diet, then a calcium deficiency develops. With time the ferret will lose weight and become reluctant to play. Eventually the bones will not have enough calcium in them, so bone fractures can occur.
In countries where ferrets are fed homemade diets consisting of meat and organ tissue only, young ferrets commonly develop bone problems and are unable to stand up because their bones are so weak. They will often try to move by crawling or “swimming.” These kits are often called “swimmers.” Most commercial ferret diets have the correct amount of calcium and phosphorus to avoid this serious problem.
On the Frankenprey diet, our ferrets eat bone and that provides Calcium. Eating Whole prey also means that they are eating bone.
If you find that your ferret food does not include enough Calcium, than you can supplement with Bone Meal Powder, such as the NOW brand product or the KAL product. Human grade is better and you want 1/2 tsp per 8oz of meat.
Vitamins:
Vitamins are also important in your ferret’s diet. They help your ferret’s body metabolize the food he eats. It has not yet been determined what levels of vitamins are actually needed in a ferret’s diet. Generally speaking, if your ferret is on a premium ferret diet there should be adequate amounts of vitamins in his diet already.
Fat soluble vitamins, such as vitamins A, D3, and E, are stored by the body for later use if they are not immediately needed.
These three vitamins are found in high levels in most of the fatty acid supplements that are available in many pet stores. Moderation should be the rule when giving supplements to your pet as ferrets may develop vitamin toxicity if constantly overfed high doses of fat-soluble vitamins.
Vitamin C (Ascorbic acid) is a water-soluble vitamin that is needed to prevent diseases such as scurvy. Fortunately ferrets’ bodies are generally able to produce adequate levels of vitamin C on their own. Many people who are into holistic medicine recommend additional doses of vitamin C in the ferret’s cancer prevention or treatment. Whether this additional vitamin C is actually helpful to ferrets has not been clinically proven, but in individual cases it seems to have helped many ferrets. Since vitamin C is water soluble, excess vitamin C in the ferret’s system is usually eliminated through his urine. You usually can’t over-dose a ferret with vitamin C, but why waste it.
The ‘B’ vitamins, Thiamin (Bl), Riboflavin (B2), Pyroxidine (B6), Cyanocobalamin (B12), plus Niacin, Pantothenic Acid, Folic Acid, Biotin, and Choline are also water-soluble vitamins. These vitamins are found in adequate quantities in premium ferret foods and no further supplementation is needed.
We recommend at least one red meat meal per week.
Minerals
Minerals are a necessary part of your ferret’s diet, but proper quantities of each mineral can be more critical – and less forgiving – than vitamins. Minerals are usually divided into two classes – Macro minerals and Micro (or trace) minerals.
Macro minerals, as their name implies, are required in larger quantities in the body. These include calcium, phosphorous, potassium, sodium, chloride, magnesium, and sulfur. These macro minerals help your ferret develop strong bones and muscles and control the absorption and release of fluids throughout the ferret’s body.
Micro minerals are required in much smaller quantities. The amounts needed are so small that they are referred to in parts per million (ppm). Some micro minerals are: zinc, copper, iron, iodine, manganese, and selenium.
Sub-groupings of trace minerals, sometimes, called ‘micro-trace’ minerals, are measured in parts per billion (ppb). These ‘micro-trace’ minerals include: chromium, fluorine, nickel, vanadium, silica, lithium, and arsenic. Strangely enough, while these minerals are all necessary for the continued health of your ferret, they can also be toxic or life threatening in high or unbalanced doses.
Liver is full of Vitamin A but too much can build up in their systems and we recommend 5 percent of their weekly intake be Liver. No more.
Usually, if a ferret is on a high quality food, these minerals will be adequately provided without the addition of mineral supplements.
As a holistic forum, we would love to see your ferrets on Frankenprey or Whole Prey.
Commercial grinds or Freeze dried raw are other options, but you will want to clean your ferret's teeth. Just like us, tartar can lead to heart disease, gingivitis, and tooth decay and loss.
I don't feed commercial grinds, but we will find a ferrent who does and get back to you with some suitable, high quality options.
I know this is alot of reading, but I hope it helps some.
Our goal is to keep your little ones healthy, avoid the dreaded illnesses that older ferrets on an improper diet will contract and bring you years of happiness with your ferrets.