Avian Conversations

(March/April 2001)

by: Tom Riggs and Ross Bishop

THE BASIC AVIAN DIET

Let's take a look at the basic components of the avian diet: proteins, fats, carbohydrates and vitamins/minerals. Birds, like you, create energy by metabolizing protein, fat and carbohydrates. Carbohydrates are important because they are the only source of energy for the brain. Fats are a rich source of energy. Vitamins and minerals regulate and facilitate the entire process. They have no calories and are often needed in very small amounts, yet their role in good health is profound.

Proteins are important for any living thing, and the subject is complex. Proteins are made from amino acids and there are 22 different kinds. Ten of these cannot be made by the body and must be taken in directly from food. Studies in Cockatiels found that optimal growth was achieved in a diet that contained 20% crude protein.

Birds do not specifically require fat, but they need some of the essential fatty acids it contains. Of these, linoleic acid is the most important. It cannot be synthesized by the body. Seeds are rich in fats, so fat deficiency is rarely a problem for caged birds. In fact, too much fat is often a problem.

In regard to diet in general, don't be constrained by the things that you and I eat. For example, many greens that we do not normally consume such as beet tops, dandelion greens, parsley (in small amounts), collards or endive, are loaded with nutrition, and birds really like them. You may need to chop them up a bit, but they are excellent sources of nutrition.

I'm going to talk about vitamins, and I want to make a key point: Vitamin deficiencies are the most commonly reported health problems in birds. I again want to suggest that you consider a good article on basic vitamins and nutrition by Dr. McWatters, entitled " The Truth About Vitamins" that can be found at: http://www.parrothouse.com/vitamins.html

VITAMINS & MINERALS

Vitamins are divided into two groups: fat soluble and water soluble. Vitamins A, E, K & D are fat soluble, the rest (all of the B's, Vitamin C, etc.) are water soluble. This difference is important.

Water soluble vitamins are not stored in the body so that regular intake of them is necessary. It's difficult to overdose on natural water solubles because the body excretes any excess. Their solubility also means that they are more easily leached out of vegetables during cooking and processing (they are also more susceptible to the effects of time, temperature and light). That is why fresh (not cooked) fruit and vegetables are important to a birds' diet.

Since organic foods are 3 to 100 times more nutritious, just think how much stronger our health would be if we ate organic!

Fat soluble vitamins are stored in the body (primarily in the liver) and the body can go for a time without replenishing them as it will draw upon its reserves. The fat solubles can be overdosed. They are also more stable in foods and less affected by cooking and processing. (Note: We are deeply indebted to Kathy Dezern and Dr. McWatters for their help and expertise in preparing the following material.)

VITAMIN A

Vitamin A (fat soluble) is important to birds, and Vitamin A deficiency is a common problem. Vitamin A is often referred to as the "anti infection" vitamin. It keeps the epithelial cells which line the respiratory, digestive urinary tracts and cloaca elastic and healthy. This lining acts as a barrier to infection.

The cells that line the respiratory, reproductive and digestive tracts change when a bird is the deficient in vitamin A, making them unable to secrete mucous. Mucous acts as a protective barrier, preventing invasion from disease causing agents. Symptoms of Vitamin A deficiency depend on which organ system is affected and which pathogen is infecting the bird.

Because the respiratory system is most often affected, a bird with Vitamin A deficiency will display any of the following symptoms: sneezing, wheezing, gagging, plugged or crusted nostrils, nasal discharge, lethargy, depression, diarrhea, loss of appetite or weight loss, eye discharge or swollen eyes.

Most of the darker leafed vegetables like dandelion greens, alfalfa sprouts, kale, collard greens, mustard greens, turnip greens, broccoli and beet greens are good sources of Vitamin A, as are yellow squash, sweet potatoes/yams, carrots and egg yolks, In addition the fish oils, particularly cod liver oil, are also good sources of vitamin A. Being from the southwest, I have to add that chili peppers are also a particularly good source of Vitamin A.

Be selective about the darker greens you feed your birds, because some of the greens like spinach, rhubarb (potentially toxic) and chard, although good sources of Vitamin A, contain oxalates that bind up calcium (see calcium below) making it unusable to the bird.

Incidentally, also be careful of artificial Vitamin A. In a natural state, vitamin A comes from beta carotene. Birds will absorb only what they need from beta carotene, and they cannot over consume it. Unfortunately, this is not true of artificial vitamin A. Too much artificial Vitamin A can cause liver and bone disease. (Tell me there isn't a difference between natural and chemical vitamins!)

CALCIUM

Calcium is not only necessary for bone and egg formation but also for normal cellular physiology. This is important to remember: All muscle contractions including those of the heart are dependent on normal levels of calcium in the body. Calcium comes in two basic forms - water soluble (bicarbonate) and carbonate. The water soluble (bocarbonate) forms are mostly found in fruits and vegetables. This calcium is readily absorbed and used. The carbonated form is mostly found in things like eggshell, cuttlebone and grit. Unfortunately, this carbonated form of calcium although abundant and inexpensive, is not easily assimilated. Most of that calcium that a bird consumes goes straight through the gut, out the tailpipe and onto the cage floor. To speak of it in a more dignified way, the intestines do not readily absorb carbonated calcium very well. Incidentally, stress and inactivity (small cages) also deplete calcium levels in the body.

Vitamin D3 is necessary for the bird to absorb calcium. Vitamin D3 must be converted over a two day process in the liver and kidneys to ultimately form a calcium binding protein. Therefore normal liver and kidney function are also necessary for the proper absorption of calcium. The rate of calcium absorption is directly proportional to the quantity of this calcium binding protein in the intestinal cells.

Of interest to bird breeders is exchangeable calcium. This is calcium salt deposited in bones which can readily enter the blood stream in times of need, such as egg laying. A hen cannot physically ingest enough calcium in a 24 hour period to compensate for the formation of an eggshell. Therefore her body must pull calcium reserves from her bones & tissue. If her body is already low in calcium, her muscles will not be able to respond, i.e. she will not be able to fly, and will "eggbind." In humans low calcium levels causes cramping and a failure of muscle function. That's why you find eggbound hens sitting in the bottom of the cage. They cannot fly. The hen will also be in a highly stressed condition. However, the term "eggbinding" is something of a misnomer. The truth is, the egg is just sitting there, but the hen does not have the ability to contract her muscles and expel it (no small task in itself). A dose of absorbable liquid calcium will bring almost immediate results.

The need for good levels of calcium in the body is why it is critical to only breed mature hens in good condition and to feed and exercise them properly several months prior to breeding. Immature and poorly conditioned hens will not have adequate body calcium reserves resulting in hypocalcemia (low blood levels of calcium), i.e. eggbinding.

I mentioned that some dark, leafy greens interfere with the absorption of calcium. In "Calcium in Cage Bird Nutrition" Robert Black writes "Another acid that goes by the name of oxalic acid is found in spinach, beet greens, chard, and rhubarb. Oxalic acid in the digestive tract combines with calcium to form a compound called calcium oxalate. The body cannot absorb this compound through the intestinal walls, and it passes through the digestive system and is excreted. Any breeder who regularly feeds any of these vegetables to the birds is likely to note calcium problems in the flock." 

Dark leafy greens are such good sources of nutrition it is difficult to recommend that you not feed oxalated ones to your birds. But, if you chose to, it is important that you not overfeed them, because you will create problems. What's too much? That is the dilemma. The amount of oxalate in a plant varies considerably on growing conditions and whether it is raw or cooked (cooked foods are higher). My choice is to avoid these greens (spinach, chard, beet greens, parsley and rhubarb (which is toxic anyway) because there are acceptable substitutes available such as dandelion, collard greens, turnip greens, mustard greens, chicory, broccoli, egg shells, cuttlebone, mineral block, brewer's yeast, oats and kelp.  If you are looking for a supplement beside good diet, the best calcium to look for is calcium/magnesium liquid. This means it is water soluble. Also look for a supplement that contains calcium lactate, gluconate and citrate because it will be even more absorbable.

VITAMIN D3 (fat soluble)

The precursor to Vitamin D3 (7-dehydrocholestrol) is produced in the bird's preen gland and is spread over the feathers during preening. When this precursor is exposed to sunlight it is then converted into Vitamin D3. The D3 is then ingested when the bird preens again. In chickens it was found that 11-45 minutes of daily exposure to unfiltered sunlight (no window glass) provided sufficient vitamin D3 production for good health. As mentioned above, Vitamin D3 maintains the bird's calcium levels. It also helps in the assimilation of Phosphorous.

A lack of D3 creates symptoms similar to a calcium deficiency (egg binding, thin or soft shelled eggs, low clutch size, leg weakness, tremors). Excess Vitamin D3 in the diet can calcify organs, especially the kidneys. This is a special problem for Macaws. Cockatiels fed 4 times the required amount of D3 dropped in egg production after a year and experienced kidney calcification. The condition did eventually clear up when dietary levels were returned to normal, however.

Good sources of natural vitamin D are: Egg yolk (boiled only 8 minutes to preserve nutritional value), direct sunlight, Vita-Lites, fish-liver oil, yams and dark leafy vegetables.

VITAMIN E (fat soluble)

The body's natural metabolizing of food produces free-radical byproducts.  Over time, free-radicals can cause damage to body cells unless they are stabilized or scavenged and removed. Anti-oxidants stabilize free-radicals, preventing them from causing this damage. Vitamin E is an important anti-oxidant.

Vitamin E is found naturally in eight forms. The most common is Alpha Tocopherol. This form is most often produced artificially as a vitamin supplement. The other forms of vitamin E, although low in quantity, are very important for neutralizing free radicals that the Alpha Tocopherol does not.  Over supplementation with manufactured Alpha Tocopherol type E can reduce the other seven forms in the body. It also prevents the absorption of calcium in the gut and will actually decalcify a bird's bones.  On the other hand, Vitamin E from a whole food source will help recalcify bone. So once again, be careful with manufactured vitamins. Sources of vitamins from whole foods is always best. Green leafy plants are generally good sources of Vitamin E, as are egg yolk, alfalfa sprouts, oats, corn, lima beans, sunflower seeds and safflower oil. Wheat germ has a very high content of Vitamin E. However, watch out for rancid fats (old seed) because it will absorb good Vitamin E from the body. Incidentally, one good way to tell if seed is reasonably fresh is to sprout it. Old seed will not sprout well (less than 50% of the seeds will sprout). It's not the most reliable test, but it can help.

MAGNESIUM

Magnesium is important to cell metabolism. It helps to regulate the acid-alkaline balance in the body and promotes the absorption and metabolism of other minerals, especially calcium. Dr. McWatters comments on the relationship between Vitamin D, calcium and magnesium: "The proper ratio of vitamin D in the diet is necessary for proper metabolism of magnesium. The ratio of calcium to phosphorus and calcium to magnesium is important in the absorption, use, and excretion of these minerals. Magnesium should be in an equal amount to phosphorus, and both should be half that to calcium." (Avian Nutrition with Dr Alicia McWatters, "The Importance of Calcium In Your Grey's Diet," Copyright 1997 by Alicia McWatters, Ph.D., C.N.C. (http://www.parrothouse.com/calcium.html)  Good sources of magnesium are: grains, dark green vegetables, apples, most seeds and wheat germ.

PHOSPHORUS

Phosphorous is important for many things in the body like cell development, healthy nerve tissue and proper heart and kidney function. In the diet both phosphorous and magnesium should be available in equal amounts and these should be about half as much as the levels of calcium. Since seed is high in phosphorous it is easy for caged birds to throw the desirable 2.5 to 1 calcium to phosphorous ratio out of whack. Over consumption of phosphorous will interfere with calcium absorption, leading to hypocalcemia (low blood levels of calcium). Foods high in protein such as seed, hard boiled eggs, corn, brown rice and yogurt are usually good sources of phosphorous.

IRON

Iron is important because it combines with copper and proteins for healthy hemoglobin production. It is essential for stress and disease resistance.  Iron is found in eggs, green leafy vegetables, grains, kelp, some seeds (such as sesame, sunflower and pumpkin) and raisins.

VITAMIN K (fat soluble)

Vitamin K is important for blood clotting. And if you've ever cut a bird's toenail too close you'll appreciate it's value. Vitamin K is also useful for normal functioning of the liver and for strong bones. Deficiencies are rare as Vitamin K is manufactured by the natural gut flora (bacteria) as are vitamins like B2, B12, Folic Acid and Biotin. But, this process is destroyed by the introduction of antibiotics. That is one of the reasons it is unwise to be liberal and indiscriminate with the application of antibiotics. Vitamin K does not take to freezing very well. Good sources of Vitamin K are: kelp, alfalfa, most green leafy vegetables, eggs, soybeans, olive oil and canola oil.

THIAMINE (B1) (water soluble)

Thiamine is freely available from many foods. It requires constant uptake as it cannot be stored. Many of the chemical additives and preservatives such as sulfates and nitrates, caffeine and tannin break down Thiamine, as does cooking. Deficient symptoms are decreased appetite, incoordination, moon gazing and seizures.

VITAMIN C (water soluble)

Primates (us) and Guinea Pigs are the only animals that do not produce Vitamin C naturally and must supplement it through diet. Research has shown that extra Vitamin C is sometimes useful to Psittacines and Passerines under stress conditions like moulting, egg production, etc. We don't know about finches, but most educated guesses say yes in regard to softbills. 

The list of other necessary vitamins & minerals is extensive and too long to list in detail here: B2 (Riboflavin), B3 Niacin, B5 Pantothenic Acid, B12, zinc, selenium, Choline, Biotin, etc. Some reading about vitamins and minerals would be good for all of us - for ourselves and for our birds.

SOFTBILLS

Ross: The "rules" say that softbills tend to be fruit and insect eaters and finches tend to be seed eaters, and although that is basically true, you've got to be careful because there are many exceptions to the rule. In nature birds do not conform to those strict rules and we need to be mindful of that.

Tom: Softbills, in most cases, need a very varied diet,. They need a good insectivorous food, which in my case is Kaytee Exact mixed with trout chow with a scattering of dehydrated carrot in it. I soak this overnight and put it through a food processor. Of course, they also get fruit in season - grapes, apples, pears, blueberries, strawberries, etc. Most of my softbills will take nectar except the Niltavas and Shamas. All my Mesias, Pekin Robins, Lories, Sunbirds, Honeycreepers and Chloropsis take nectar. I have also recently discovered that my Amethyst Starlings also take nectar. My softbills take mealworms, crickets, grubs and wax worms. I also culture fruit flies for my Sunbirds, Honeycreepers and Bearded Reedlings. Plus in the summer months they pick up whatever naturally comes into the outside aviary.

In my time have probably tried every conceivable nectar recipe known to aviculture. Some of them worked well for some species, others did not. So I for one, am very grateful for the research that has been done on the needs of the primary nectar feeders such as Sunbirds, Hummingbirds and Lories. I use Nekton products which have proven very effective for my nectar feeders. Much of the breeding of Hummingbirds and Honeycreepers, Sunbirds has occurred since the introduction of Nekton Products as well as other companies. My Rothschild Fairy Lorikeets came to me as a pair that had never completed the raising of a chick. They had been on a very nutritious hand prepared diet. I put them on Lorie strength Nektar Plus and in the two years I have had them they have raised two beautiful chicks on their own. A female last season and a male this year. I attribute this to several factors, but certainly consider the Nektar a major contributor to their breeding success.