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Nutritional Requirements of Companion Birds
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Companion birds require food that is high in nutritional value. To obtain this, they need a varied, balanced diet; no single food source will provide that for them. In the wild, these species usually forage for what they need from the foodstuffs available to them throughout the year and have a huge variety of foods from which to choose —fruits, seeds, insects, and vegetation; but in captivity, it is the owner’s responsibility to offer them the foods that will keep them healthy and happy.
1. What is Nutrition?
Nutrients are foods that supply the energy to maintain life. These nutrients are provided by macromolecules which fulfil most of the requirements of the diet . Micronutrients are the smaller components of the diet and consist of vitamins and minerals. and other trace elements. For birds to be healthy, these nutrients must provide optimal health and be available to meet the body’s metabolic demands .
The minimum amount of a nutrient that meets these criteria is considered the requirement for that nutrient . It is difficult to estimate the nutritional requirements for companion birds; most are not well known since each species will have its own set of requirements. Most values are referred to as the “best educated guess” .
Birds need clean water in clean dishes provided for them every day, and the water should be changed during the day if it becomes soiled. Water intake depends on the species, environmental temperatures, and the bird’s diet. Vitamins and minerals should not be added to the bird’s water; minerals such as zinc, iron, and copper can destroy vitamins through oxidation, and many vitamins are light-sensitive. It is impossible to know how much of the supplements are being taken in by the bird when they are placed in the water. Supplemental toxicosis can take place, and dehydration is a possibility if the bird refuses to drink because of the taste, color, or texture of the water . Lafeber now has a vitamin mixture that can be added to water because it is hydrolyzed and will not oxidize. It is VIVI 13 and it may be procured from your avian veterinarian. Sources of VIVI 13 and other Lafeber products around the world may be found at their website. Qualified veterinary professionals in the USA may purchase Lafeber products online.
Most psittacine illnesses are related to nutritional imbalances. Diseases may have many causes, and poor nutrition is often one of them. The nutritional cause of the illness is difficult to pinpoint since nutritional values for many of the psittacine species have yet to be established. The nutritional requirements that have been published continue to be based on those known for chickens since those are known, and the physiology of psittacines is similar to those of chickens .
Malnutrition and the Ailing Bird
Sometimes an ailment can be directly traced to a nutritional imbalance. Some illnesses can increase nutritional requirements, making a normally good diet inadequate for the sick bird’s metabolic needs . Malnutrition causes diseases which affect all body systems, feathers, and skin. The condition of the skin, feathers, and beak is an excellent indicator of the nutritional status of the bird. Malnutrition affects the bird’s moods, behavior, and activity levels [18,22].
Malnutrition’s Effect on Growth
When malnutrition leads to poor growth and low body weight, the causes are:
- Insufficient quantity of food, infrequent feeding, or too-early weaning to solid foods.
- Hand-raising, now considered inferior to parent-raising and co-parenting of chicks.
- Inappropriate diet and unfamiliar food items.
- Loss of appetite, maldigestion, or poor assimilation of food .
Unless there is a medical cause, such as pancreatic disease, low body weight or poor weight gain can be improved by providing a high-energy diet along with digestive enzymes and fiber hemicellulose to increase the digestibility and absorption of the nutrients . The use of Lafeber’s Emeraid Critical Care© formula will increase the appetite.
Other Variables Play a Role in Malnutrition
- The bird’s age, sex, mental and physiological states
- The variation in required nutrients and clinical signs of malnutrition among species
- Pathogens, such as parasites, bacterial infections, mycotoxins (fungal diseases), and viruses which may interfere with the absorption of nutrients from the digestive tract .
3. Formulated Diets (Pellets), also Known as “Extruded” or “Complete” Diets
Pellets are a mixture of seeds, grains, vitamins, and minerals combined to create a balanced formula. The mix is finely ground then placed in a pelleter under heat and pressure .
The Rise in Popularity of Conversion to the “Complete” Diet
During the 1970’s, 1980’s, and 1990’s when the bird trade was at its peak, poor body condition and multiple illnesses plagued many birds since little was known about their nutritional needs. In addition, seed-only diets were the norm. While seeds may be a part of the overall diet, a seed-based diet alone is not sufficient to provide the nutrients needed, even if it is supplemented with fruits and vegetables, since those are mostly water .
When permitted to choose their own foods, birds often choose diets that are deficient in needed vitamins, minerals, and amino acids. In the late 1990’s, the pelleted diet was developed to solve this problem. Extruded foods presumably provided the proper nutrients above the estimated requirements. Manufacturers touted that with this food the bird gets everything it needs. The addition of pellets to the diet resulted in improved overall health for many birds. While the total conversion seemed helpful at the time, it is no longer considered beneficial for the bird .
Advantages of Conversion
Readily available, cost-effective, and convenient. Owners don’t have to buy other foods.
Easy to use; they take the guesswork out of feeding.
Responsible for improving the health of many birds who had been on all-seed diets .
Disadvantages of Conversion
Some manufacturers have aggressively pressured veterinarians to persuade their clients to convert their birds to extruded diets. The birds are resistant and behavioral issues arise from frustration and boredom; thus, both the owners and birds suffer. In order to follow their instructions to convert, some owners have resorted to withholding other foods, forcing the birds to eat only the pellets and not giving the birds enough time to adapt. This drastic approach has resulted in refusal to eat, weight loss leading to starvation and death, and hysterical behaviors in birds who are unwilling to change their diets [18,27].
In the years since the introduction of pellets, clinicians who had previously seen patients’ illnesses caused by nutritional deficiencies resulting from seed-only diets are now treating birds for ailments attributed to toxicities due to the addition of vitamins and minerals to an all-pelleted diet. Over 90% of vitamins are stored in the liver; therefore, over-supplementation due to excess vitamin, mineral, fat, or protein consumption has led to significant liver disease [18,23,37].
There are other drawbacks to converting birds to a totally pelleted diet:
- Pelleted diets do not provide the variety needed for species that usually has a huge selection of food items in the wild. This leads to boredom and stress, which then lead to behavioral issues such as screaming, feather and skin mutilation, and biting [27-29].
- Birds have difficulty adapting because they are not used to them and are resistant to conversion. It can take a year or more for a bird to convert; meanwhile, he is under great stress and frustration, and so is the owner [18,29].
- Nutritional quality is limited by the knowledge of the manufacturer and the conditions of packaging and conservation .
- Pelleted diets offer no opportunity for birds to display their innate foraging behavior; in the wild, they will spend at least 50% of their time in this activity [18,29].
- Pelleted diets for small species may not contain adequate levels of calcium and protein for egg-laying .
- Pellets do not contain essential Omega-3, 6, and 9 fatty acids, other micronutrients, and the type of proteins found in seeds..
- Some birds who have been fed a pellet-only diet have developed some lesions in the kidneys due to tubular nephrosis. These have been visualized both before and after death. In live birds, these lesions were resolved once the bird’s diet was changed to include a wide variety of foods .
A More Common-sense Approach
Today, though, we see a change in attitudes toward pelleted diets. After observing 25 years of research into the effects the total conversion (or even a high percentage) to pellets has had on these birds, most veterinarians now realize that the all-pelleted diet is not preferable to a well-balanced diet which includes a wide variety of foods, including some seeds.
Formulated diets cannot provide all the nutrients that the birds need or the natural foods they enjoy, and the happiness of the bird, not just his health, must be considered. Recent studies are verifying that a bird’s general, reproductive, and mental health are improved if they are provided with a balanced diet which includes fresh fruits and vegetables, meats, some seeds, and other nutritious human and bird foods and some formulated foods if desired .
Seeds have become vilified, and those who provide them criticized. This should not be, for there is a place for seeds in the diet. The quantity and quality of the seeds must be carefully chosen, and the correct seeds made part of a well-balanced diet. Seeds high in fat and cholesterol, such as sunflower and safflower seeds, should be minimized or eliminated from the diet. “Given in moderation, seeds are a good addition to the diet. They supply needed micronutrients not found in other foods.” (R. Dahlhausen, personal communication.)
4. The Use of Grit
Grit is finely ground stone or shells. Some owners feed their birds oyster shells or other forms of grit and shells. Birds that eat their seeds whole require a stronger stomach for grinding; the term for the gastric stomach in birds that eat seeds whole is “gizzard.” Psittacines shell their seeds before eating them, so they do not require grit, and their two-part stomachs are called proventriculus and ventriculus. Grit causes impactions of the crop, proventriculus, and ventriculus, and the charcoal in grit interferes with absorption of Vitamins A, B2 and K. It leads to liver disease, pancreatic inflammation, renal (kidney) dysfunction and general malnutrition. Grit should never be given to birds in the parrot family [23,45].
Figure 1. Grit impaction in the ventriculus causing coelomitis (inflammation in the body cavity). Severely enlarged fluid/soft-tissue density and cranial displacement of the ventriculus result (image courtesy of H. Bowles; used with permission).
5. Dairy Products
Birds are unable to digest the lactobacillus bacteria in cow’s milk. It is preferable to give them rice, almond, or other non-lactose milk. Any product made with lactose, including yogurt, soft cheese, and cottage cheese, should not be given to birds; however, a small amount of hard cheese may be offered from time to time (R. Dahlhausen, personal communication) .
6. Dandelion Greens
These greens are popular with some bird owners, but they can be dangerous. They can be toxic because they contain phytoestrogens that affect reproduction. The stems in particular are dangerous since the stalks contain a great deal of latex which is an irritant .
Symptoms of Dandelion Poisoning
- Irritation of the mouth, throat, and stomach, and great thirst
- Intestinal distress, vomiting, diarrhea
- Seizures, cardiac arrest
- Respiratory difficulties 
Dandelion Greens are Rich in Oxalates and can Cause Damage to the Body
Oxalate-rich foods prevent the body from absorbing magnesium, copper, iron, and calcium. They are toxic to the kidneys and form oxalic acid crystals that do not dissolve. These crystals can be found throughout the body, including the brain, and can cause damage to the kidneys, arteries, stomach and other organs. The acid is corrosive on the mucous membranes .
7. Obesity Due to High-Fat, High-Cholesterol Diets
Obesity has become a common and severe problem often seen in avian practice. Birds eat to meet their daily metabolic requirements, and they often consume foods which are higher in energy content than they require. Fats provide a concentrated, immediate source of energy, and extremely active companion birds need this additional energy. However, most companion birds are sedentary and get very little exercise, so the fats in their diets lead to obesity. Note the puffed-out breasts of the birds in the pictures below [19,23,28]. Amazons, budgerigars, canaries, cockatiels, cockatoos, and Quaker parakeets are predisposed to obesity .
Complications from High-Fat Diets and Obesity
- Crop infection, diarrhea, and poor calcium uptake in the intestines [19,23]
- Fat deposits in the coelomic (internal) cavity and along the neck, clavicular regions, breast area, body wall, abdomen, and vent .
- Pancreatitis and respiratory distress 
- Self-mutilation and feather loss over the breast, common in obese budgerigars 
- Necrotic (dead) tissue, and sometimes death of the bird .
Figure 2. Obesity can cause respiratory distress. This bird has a severe case of dyspnea (difficult breathing) and was critically ill and placed in an oxygen cage. It is open-mouthed breathing, and its neck is extended in an effort to get air (image courtesy of Look for diagnosis; used with permission).
Figure 3. Obese budgerigar (image courtesy of Currumbin Valley Veterinary Services; used with permission).
Fat in the Diet
Fat is an important part of a bird’s diet. It provides energy, aids in the absorption of calcium and the fat-soluble vitamins, and is needed for the formation of amino acids. However, diets that are high in fats, especially saturated fats, can cause obesity, heart disease, and hepatic lipidosis (fatty liver disease) in birds .
The beneficial fats are mono-and polyunsaturated fats, and they are needed to provide nutrients for cell maintenance. They are antioxidants when combined with Vitamin E. Saturated and transfats provide fuel; they are necessary but also problematic when overeaten. The largest amount of saturated fats is found in foods from animal sources, such as meat, dairy, and certain vegetable oils, such as palm and coconut oil, egg yolks, grains, nuts, and seeds. Foods high in monounsaturated fats include plant-based liquid oils such as olive, canola, peanut, safflower, and sesame oil .
Obesity, Due to Over-consumption and Sedentary Lifestyle
Birds overeat to obtain nutrients not found in their diets. Many birds are fed excess quantities of improper foods such as sweets, nuts, and peanuts (which should not be given to birds due to mold toxicity). Captive birds do not spend time foraging like their wild counterparts, so boredom sets in, and obesity and behavioral issues result [19,28,29].
Figure 4. Subcutaneous fat deposits in a cockatiel (image courtesy of Lafebervet; used with permission).
A sedentary lifestyle is a common contributor to obesity. Birds are fed too much food or fed diets high in fat, such as sunflower and safflower seeds. "Behavioral problems can be seen in sedentary birds: depression, repetitive or stereotypic movements, and feather-destructive behavior" . The client needs to understand and agree the bird is overweight, understand why weight loss is important, and be willing and able to address the problem .
Figure 5. Young sulphur crested female with fat deposits which have displaced the organs. She was fed a seed diet and snacks of potato chips and crackers (image courtesy of P. Macwhirter; used with permission ).
8. Commonly Known Diseases Caused by Malnutrition
Atherosclerosis is the hardening of the arteries due to plaque formation associated with lipid (fat) deposits [18,32]. These plaques occur in the heart, its great vessels, and peripheral vessels . There is no test as of now to diagnose it in living birds. Although dietary fat and cholesterol lead to atherosclerosis, it is also caused by prolonged chronic inflammation and hyperlipidemia, or too much fat in the blood [32,40].The type of dietary fat eaten affects the development of atherosclerosis more than the total amount of fat consumed [23,32]. Nutritional deficiencies, age, species susceptibility, exposure to some infectious agents, and lack of exercise lead to the development of this disease [14,31,40].
Atherosclerosis leads to stroke, heart attack, and vascular disease and is seen in parrots with increasing frequency. The clinical signs for birds include circulatory conditions, lethargy, dyspnea, fainting, sudden falling, nervous symptoms due to blood loss in areas of the body, and sudden death . African greys, cockatoos, and Amazons appear to be predisposed to it, and there is growing evidence that as many as 2-6% of birds are affected [18,31,40].
Figure 6. Atherosclerosis in the avian heart. Fat builds up in the aortic arch (arrow) and is carried by the blood and deposited internally and externally (image Courtesy of H. Beaufrere; used with permission.)
Figure 7. Necropsy of Blue-fronted Amazon with pericarditis urica. Uric acid deposits can be seen on the pericardium (1) that covers the heart and liver (2). The discoloration of the large vessels (3) indicates atherosclerosis (image courtesy of M. Pees; used with permission).
Figure 8. "Blood is made up of solids and liquids. When we put blood through a centrifuge, it separates into two main components - cells (the dark part) and the plasma (the liquid on top). On the right is blood from a healthy cockatiel, who eats a combination of vegetables, fruit, pellets and seed. On the left is a cockatiel that is offered only seed, and of those seeds this individual likes to pick out the sunflowers. What you're seeing is the cholesterol and fat proportion of this bird's blood sitting on top as a solid chunk of fat. The individual's blood cholesterol was off the chart. The bird presented for collapse, head tilt and stroke-like behavior, which is no surprise given how sludgy this blood would be passing through the heart and brain." (Image and text credit Bird and Exotic Animal Clinic; used with permission).
Fatty Liver Disease (Hepatic lipidosis)
Hepatic lipidosis is caused by high-fat foods, B-vitamin deficiencies, and obesity . It is a slow, on-going, progressive disease in which the liver tissue is replaced with fat. Females appear to be more affected than males; this may be linked to the hormonal activities in the reproductive hen. Also, juvenile, hand-fed birds that are overfed or hand-fed long after they should have been weaned are often diagnosed with it. Handfeeding formulas are calorie-dense, and baby birds tend to be sedentary; any extra calories tend to end up being stored as fat in the liver. This is most often seen in cockatoos as they tend to beg even after satiated. Birds on an all-seed diet may be expected of have some diminished liver function. It is not usually noticed until the liver is at its end stage .
Figure 9. A: Hepatic lipidosis from sunflower seed and peanut diet in an Amazon. B: Normal liver (images courtesy of Thalita Quete; used with permission).
- Cachexia (a wasting syndrome) 
- Glossy, black feathers due to the exposure of melanin from the green and blue pigments
- Hepatomegaly (enlarged liver) and ascites (excess fluid in the abdominal cavity) resulting in dyspnea, weight loss, diarrhea, and bruising and bleeding of the skin 
- Breathing difficulties as the organ compromises the body cavity space
- Distended abdomen; sometimes the liver is actually visible below the keel
- Yellow or green droppings due to biliverdin (green bile pigment) being excreted
- Poor feather quality and changes in the feather coloration. Cockatiels’ white feathers may become yellow. African Greys may develop red feathers in areas that are usually grey, and feathers in eclectus may turn yellow, orange, or red.
- Dry, itchy skin. Once the liver problems have been resolved, the itching eventually stops.
- Soft areas around the beak; overgrown and bruised beaks and nails
- End-stage liver disease. Toxins build up in the bloodstream, resulting in Central Nervous System (CNS) signs, such as disorientation or seizures [15,37].
- Subcutaneous hemorrhaging and poor blood clotting. Any cut or broken blood feather may result in prolonged, life-threatening bleeding [5,37].
Affected birds’ diets should be low in protein, highly digestible, with moderate amounts of fiber. To ease the load on the liver, food should be divided into smaller, more frequent meals .
Figure 10. Yellow-naped amazon on seed and table-food diet. There is a keratin accumulation on the feet and beak, indicating liver disease (image courtesy of B. Doneley; used with permission).
Figure 11. Bleeding into the maxillary rhinotheca (upper beak) associated with liver disease (image courtesy of MelbBirdVet; used with permission).
Hepatic Lipidosis Progression
"Hepatocytes are epithelial cells (ones that line the surfaces of the organ and tissues) in the liver. Fatty infiltrates build up on them, die off, then get replaced with scar tissue. That shrinks, and the liver tissue gets hard and thin, resulting in a firm, non-functioning liver. This then becomes cirrhosis of the liver." (R. Dahlhausen, personal communication).
Hepatic encephalopathy is a complication of liver disease. Brain function decreases when the liver is unable to remove toxins from the blood . Silymarin (milk thistle) is a good supplement for the liver. If used early in the disease, it can reverse the damage to the liver when used with improved diet .
Figure 12. Abnormal "gold" lutino cockatiel with liver disease on the left compared to a normal lutino shown on the right (image courtesy of MelbBirdVet; used with permission).
Figure 13. Fatty Liver disease with bloody lesions (image courtesy of MelbBirdVet; used with permission).
Figure 14. Long beak due to fatty liver disease. The beak becomes brittle, flaky, and overgrown. Treatment: correcting the dietary imbalances and trimming the overgrown beak. Care must be taken with beak trimming due to excessive bleeding if the “quick” is damaged. (Image credit Currumbin Veterinary Services).
Xanthomas are fat and cholesterol growths which invade the blood stream and cause excessive hemorrhaging. This bird bled to death from these growths. They can occur both externally (usually on the wings) and internally around the heart at the aortic arch. Xanthomas are commonly found in cockatiels and budgerigars. These are yellowish nodules which can be found over a lipoma, may become ulcerative, and can lead to cancer .
Figure 15. Obese bird with xanthomas and lipomas (image courtesy of Belinda James; used with permission).
Lipomas are benign, fatty growths in the soft tissues and bloodstream which are caused by poor nutrition, high-fat diets, obesity, hypothyroidism, and genetic factors. They are usually small and occur under the skin. They can be superficial, as on the neck, back, or abdomen, or deep, as on muscle or bone. They can grow large enough to inhibit perching or flying [19,23].
Figure 16.Lipoma in an ill bird (image courtesy of Julie Burge; used with permission).
Liposarcomas are malignant, invasive fatty growths which metastasize quickly. They are firm and highly vascularized and often found on breast, in the uropygial (preen) gland, abdominal cavity, liver, or skeletal muscles [19,23].
Hypoglycemia (Low Blood Sugar) and Diabetes
Glucagon, not insulin, is the principal director of carbohydrate metabolism in birds. Small companion birds may collapse from hypoglycemia if deprived of food for even short periods . Excess glucagon in the bloodstream results in avian diabetes. Glucagon keeps blood sugar in the normal range, but with diabetes mellitus, the glucagon forces the body to release or produce glucose. Glucagon overproduction will cause the blood sugar level to rise. Treatment consists of converting to a high-energy, high-protein, glucose diet. Birds need easily digestible carbohydrates since liver disease decreases the absorption and storage of Vitamins A and D and inhibits the synthesis of Vitamin C [23,24,38].
Carbohydrates and Blood Glucose Levels
Carbohydrates are natural compounds that provide the majority of the bird’s energy. They are a quick source of energy and are readily converted into fats in the liver. Very active birds need a high-energy, high-protein diet, but sedentary birds on mainly seed diets tend to develop hepatic lipidosis. They need a low-protein diet, free of high-fat foods, and they should be given a variety of fresh fruits and vegetables. The protein foods should possess high biologic value, such as hard-cooked eggs and cooked chicken [18,23].
Vitamins are organic compounds that are necessary for the body’s metabolic processes. "Vitamins A, B, C, and E are vital to immune responses; deficiencies in these compounds may increase the severity of infectious diseases" .For optimum health, birds require a balanced diet and the correct vitamin supplementation. An excess of one vitamin can diminish the uptake and absorption of another nutrient. Antibiotics may cause vitamin deficiencies and can interfere with the action of normal intestinal microflora, so birds on antibiotics should receive multivitamin supplementation. Many vitamins require other vitamins or minerals in order to work properly, but they have to be in the correct balance [18,23].
Vitamins are classified as either water-soluble or fat-soluble based on how they are absorbed and used by the body . The body does not store water-soluble vitamins (Vitamin C and all of the B vitamins), so birds must be given these vitamins daily. They dissolve in water when they are ingested and then they go into the blood stream. The body keeps what it needs at that time, and excess amounts are excreted in the urine . Fat-soluble vitamins (A, D, E and K), dissolve in fat when they are ingested. The body uses what it needs at that time and stores the rest for future use. This can lead to obesity [27,29].
Vitamin A is a fat-soluble vitamin formed in the liver . It is an essential micronutrient which affects every system in the body. Birds who eat only seeds are vulnerable to Vitamin A deficiency. The high-fat seeds, such as sunflower and safflower seeds, are low in Vitamin A and can "result in systemic disease throughout the body" .
Vitamin A is required for:
- The formation and integrity of mucous membranes, the maintenance of epithelial cells, and tissue differentiation 
- A healthy immune system and Bursa of Fabricius. This is a glandular lymph organ opening into the cloaca and producing B cells, important for the immune system 
- The integrity of all internal organs and body systems, including oral, respiratory, urogenital, GI, cardiovascular, and renal health [14,19,23]
- Healthy Central Nervous System, brain development, behavior, and vision 
- Skeletal development and growth, and growth of all organs and tissues 
- Reproduction, hormone production, embryo formation, and testosterone synthesis 
- Healthy skin and feathers, formation of pigments, and resulting colors [23,34]
Figure 17. Unusual red colors in an African grey due Hypovitaminosis A and dietary deficiencies (image courtesy of Angela Lennox, in Clinical Avian Medicine).
Consequences of Hypovitaminosis A
Diseases of the Oropharynx (Mouth and Throat), Eyes, and Sinuses
- Swollen nares (nostrils) and/or swollen cere .
- Hyperkeratinization (excess keratin) of epithelial tissues, mucous membranes, and glands of the mouth and sinuses. The tissues become heavier and thicker .
- Small, yellowish nodules in the mucus glands and ducts which often coalesce into one group. Gross lesions are initially found in the esophagus and pharynx [44,45].
- White or pale swellings in the movable hinge joints in the jaw, beneath the tongue or elsewhere in the oropharynx; plaques in the mouth [6,23]
- Abscesses or occlusion of the salivary gland ducts [14,23]
- Ocular lesions, dry eyes, thickened nictitating membranes (third eyelids), poor vision, night blindness, and total blindness [22,43,44]
- Sinus infections, caused by the thickening of the sinus lining. Mucous flow, which washes the debris from the sinuses, is reduced, and bacterial growth then leads to infection .
- Oral candidiasis (fungal disease), with raised, crusty sores on the skin of the commissures (soft sides of mouth). They will bleed if disturbed , causing:
- Necrotic lesions on the beak occurring secondarily to hypovitaminosis A [3,19]
- Abscesses that distort the glottis (opening of windpipe), causing labored breathing and mechanical suffocation. Abscesses can grow large enough to block the choanal slit (an opening in the roof of the mouth). The result is profuse nasal discharge and swelling around the eyes. The hinge joints of the jaw swell and get infected due to abscesses, and the pain from these pockets of infection will cause a bird to starve. Microorganisms spread throughout the body and cause death [6,44].
- Lesions in the esophagus and pharynx 
- Hyperkeratosis (too much keratin) and hypertrophy (enlargement) of epithelial cells, leading to obstruction of the respiratory airways [23,43]
- Rhinoliths: concretions of debris in the nares. Rhinoliths can cause:
- Metaplasia. Unhealthy tissue blocks ducts and glands, causing swelling .
- Chronic respiratory infections leading to erosions of the operculum (the little flap inside the nares) resulting in permanent disfigurement of the nares .
- Sinusitis, with a heavy discharge, and swelling of eyes and bones. When liths are not removed, abscesses fill with a yellowish, caseous (cheese-like) substance. This substance blunts the choanal papillae (small, round protuberances around the choanal slit), indicating Vitamin A deficiency [18,23].
Figure 18. Oral candidiasis (fungal disease) and bacterial disease in the mouth of a cockatiel at the commissure. Anti-fungal medications and antibiotics are needed to cure this, and resolution can take months. Plaques have formed on one side of the maxilla and mandible of the mouth in this bird (image courtesy of Jeannine Miesle).
When Vitamin A is low or absent from the diet, the cells undergo changes that prevent the secretion of mucous, thus destroying a critical line of defense against bacterial invasion. In this case, there was an evident swelling at the lower back of the mandible, in the throat area. The bird had predominantly been on a seed-based diet for most of his life. The bird was supplemented for a month with additional vitamin A. (Rina Dev, personal communication.)
Figure 19. Ragged feathers and feather loss in a cockatoo as a result of picking, poor growth, poor skin condition, and poor feather growth from malnutrition (image courtesy of April Adcock; used with permission).
Skin and Feather Damage and Disease
- Scaling, swelling, irritation, cracking, and splitting of the skin. This is a result of exfoliation of keratin on the skin surface.
- Dermatomycosis (fungal skin infection). The infection will damage keratinized layers of the epidermis and produce inflammation, leading to massive destruction of the feather follicles. Poor hygiene and husbandry contribute to the damage.
- Severe pruritus (inflamed, itching skin), a consequence of aspergillus, a mycotic (fungal) pathogen isolated from the plumage. The signs are poor feathering on the head, neck and breast and facial dermatitis with rough, scaly skin. Internally, the fungal spores, seen as caseous growths, are frequently found in the air sacs, lungs, and viscera (internal area where body organs are located) [3,14,22-24].
Figure 20. Feather damage and picking in an African Grey from poor seed diet and years in sanctuaries/rescues (image courtesy of Dawn Moulton; used with permission).
Damage to the Epithelial Cells and Mucous Membranes
- Squamous metaplasia occurs in the mucous epithelial cells lining the cloaca, ureters and collecting ducts, Bursa of Fabricius, and conjunctiva of the eye.
- The metaplasia block the ducts of the salivary and mucus glands, causing submandibular swelling involving abscesses filled with a yellowish, caseous exudate and blunting of the choanal papillae. Excessive salivation and sinusitis result.
- The respiratory, reproductive and digestive tracts undergo structural changes rendering them unable to secrete mucous which prevents invasion from pathogens. Pathogens then penetrate the mucous membrane barrier and invade the tissues [14,23,43,44].
Figure 21. Sinusitis and conjunctivitis in 20-year-old male cockatiel with inflammation from a sinus infection from a seed diet; Note profuse discharge from the eyes and nares (image courtesy of MelbBirdVet), used with permission).
Foot Damage and Bone Malformations
- Lesions develop on the plantar surface of the phalanges and tarso-metatarsus (toes and back of foot). Pododermatitis and plantar corns are associated with biotin and Vitamin A deficiencies.
- Damage to the foot tissue, keratin deposits, and bone malformations occur. The feet lose their scaliness, and lesions and corns develop on the metatarsal pads. Obesity increases the severity of the lesions.
Treatment: Vitamin B-complex, A, D3 and E injections, followed by continued oral supplementation and multivitamin-mineral-amino acid preparations [3,23]. Changing perches from rough-textured, sandpaper, dowel or warming perches to rope perches or wrapped perches. Vetrap or cohesive wrap may be used.
Figure 22. Pododermatitis in a cockatiel (image courtesy of David Perpinon; used with permission).
Parasites and Protozoa
Giardia and coccidiosis. Protozoan infections interfere with the absorption of vitamins from the intestinal tract. Treatment includes improved nutrition and supportive treatment, including Vitamins A, D3, E and B-complex, and selenium supplementation. Malabsorption of fat-soluble vitamins is possibly a mechanism of giardiasis .
Immune System Dysfunction
Sub-optimal immune response, caused by both toxicity and deficiency. Deficiency in chicks leads to rapid loss of lymphocytes (white blood cells), diarrhea, and pneumonia. Treatments: Vitamin A and Retinol (from liver and fish oils) supplementation and corrected diet [14,24].
Birds may experience reduced egg production, increased time between clutches, egg binding, poorly formed egg shells, decreased testes size, decline in sexual activity in males, decreased sperm counts and sperm motility, abnormal sperm, reduced hatchability, increased embryonic mortality, and decreased survival time of the young [23,24].
Weakness, incoordination, ataxia (poor muscle control), ruffled feathers, weight loss .
- Polydipsia (excessive thirst) and polyuria (excessive urination) may indicate squamous metaplasia, kidney damage, and water retention with uric acid deposits. The formation of uric acid crystals leads to liths and ureter obstruction, followed by gout.
- Symptoms include hypercalcemia, hypervitaminosis D, vitamin A deficiency, and excessive dietary cholesterol or protein. These may lead to nephritis and other degenerative renal changes. Treatment is Vitamin A parenterally (other than by mouth).
- Uric acid deposits lead to gout:
- Visceral gout — keratinization of the kidneys. Instead of being excreted, the urates (white part of droppings) are deposited in the internal organs.
- Articular gout - The urates are deposited in the joints of the limbs, particularly the feet and legs, causing painful crippling. The tophi (nodules) show up as whitish swellings along the bare areas of the legs, ankles and toes. Articular gout is being seen more lately with elderly birds. Treatment includes a low-protein, high-carbohydrate diet with fruits, vegetables, and Vitamin A supplementation to provide energy and increased calories. Pellets should not be part of the diet. The addition of Omega-3 polyunsaturated fatty acids may preserve renal function and delay disease progression [3,13,14,39].
Figure 23. Visceral gout on the heart of a Lory (image courtesy of Julie Burge. Used with permission).
Figure 24. Articular gout with tophi on the toe digits (image courtesy of MelbBirdVet; used with permission).
Digestive System Disease
- Anorexia, often from protozoan infections (giardia and coccidiosis) which interfere with the absorption of vitamins in the intestinal tract
- Increased susceptibility to infection and poor body condition
- Treatment includes Vitamin A, B-complex, D and E injectables in birds with calcium deficiency [23,26,29,43].
Diseases of the Uropygial Gland
- This gland may become blocked with a keratin plug, causing enlargement. It may become infected or burst if the blockage is not removed and the papillae are not expressed. This is resolved by dislodging the plug and correcting the diet imbalance to increase Vitamin A. In severe cases, the gland will need to be removed surgically.
- Tumors may occur and may require surgical correction. Treatment includes Vitamin A, B-complex, D and E injectables in birds with calcium deficiency [4,26].
Figure 25. Removal of impacted uropygial gland due to Vitamin A deficiency (image courtesy of Rina Dev; used with permission).
Figure 26. Impacted uropygial gland from all-seed diet (image courtesy of Jeannine Miesle).
Vitamin A Toxicity
This is mostly seen in birds on formulated diets who receive high supplemental levels. Pellets already contain high levels of many vitamins and minerals, and the addition of supplements creates toxicosis. Toxicity is greater in adults than young birds, and adult cockatiels are more susceptible to toxicity than deficiency [34,45].
Vitamin A Toxicity may Cause:
- Epithelial damage and keratinization of squamous cells leading to conjunctivitis
- Changes in vocalization patterns and more intense stress calls
- Changes in the number of vocalizations and reduction of the frequency.
- Hemochromatosis (Iron Storage Disease). Excess iron is stored in the liver. Lovebirds are very susceptible.
- Splenic hemosiderosis (excess iron stored in spleen)
- Digestive conditions, including enteritis, diabetes, and pancreatitis
- Skeletal abnormalities, bone deformities, disruption of long-bone growth plates, fractures, and slow growth.
- Neurological disorders and behavioral difficulties.
- Reproductive disorders: compromised fertility, hatchability, and survivability of chicks caused by excessive Vitamin A interfering with the body’s uptake of Vitamin E, which is also needed for neurological health and hormone regulation; decreased egg and sperm production, poorly formed eggshells, early embryonic death
- Immune deficiency due to impaired T-cell function (T-cells are part of the immune system) and keratinization of the Bursa of Fabricius
- Dry eye and night blindness
- Squamous metaplasia or hyperkeratinization of mucous epithelial cells lining the respiratory tract, oropharynx and salivary glands, esophagus, cloaca, ureters and collecting ducts, Bursa of Fabricius, vagina, conjunctiva
- Feather defects and parakeratosis (dry, scaly skin). Both result in persistent feather sheaths, scaliness of unfeathered skin, pruritus, poor feather development, feather-picking, and skin mutilation due to dry, flaky, pruritic (itching, infected, pus-filled) skin [14,23,24,34].
Vitamin A in Foods
Foods High in Vitamin A
- Oils, egg yolk, fish, non-dairy milk, butter.
- Dark leafy greens, such as spinach, lettuce, broccoli leaves and flowers
- Oranges, cantaloupe, mango, papaya, apricot, tomato, peaches, plums
- Yellow and orange vegetables, pureed carrots, green peppers, fresh and dried red chili peppers, sweet corn, sweet potatoes, and pumpkin [34,44,45]
Foods Low in Vitamin A
- White potatoes, summer squash
- Iceberg lettuce 
- Bananas, apples, grapes
The B-complex Vitamins
These water-soluble vitamins are necessary for immune system integrity. They cannot be stored and must be replenished daily. They work with Vitamin E to improve the body’s response to pathogens, and in some cases, can improve Central Nervous System (CNS) signs .
Vitamin B1 (Thiamine)
It is needed for CNS health, muscle function, digestion, and carbohydrate metabolism. Severe thiamine deficiency may lead to diseases in the nervous and digestive systems, brain, muscles, and heart. Hypovitaminosis B1 is uncommon in seed-eaters, since seeds and grains generally contain sufficient thiamine. It is found in yeast, whole grains, beans, peas, nuts and meat .
Hypovitaminosis B1 can cause:
- Anorexia and digestive system diseases
- Diseases in the muscles and heart.
- Adrenal hypertrophy and skin edema (fluid buildup),
- Poor physical condition and a ruffled appearance.
- Central Nervous System and brain disorders and diseases. These include polyneuritis with myelin degeneration, ascending paralysis; seizures; opisthotonos (head tilted back and back arched); torticollis (wry neck--the head turned sideways) [10,23,26].
Figure 27. Torticollis in an Amazon aestiva (image courtesy of Thalita Quete; used with permission).
Figure 28. Young cockatiel with dorsiflexion of the neck from opisthotonos (image courtesy of S. Platt; used with permission).
Vitamin B2 (Riboflavin)
Vitamin B2 (Riboflavin) is responsible for the metabolizing of fats, carbohydrates, and proteins. It supports energy production and is essential for healthy skin, beak and nails, general health, red blood cell formation, respiration, antibody production, regulating growth, reproduction, and thyroid activity. Treatment includes the addition of dietary sources such as grains and leafy green plant material to the diet and supplementation [10,23].
Hypovitaminosis B2 can cause:
- Curled-toe paralysis (walking on hocks with toes curled inward) in poultry and nesting budgerigars. Chronic cases have resulted in irreversible damage.
- Weakness, muscle atrophy, diarrhea, and emaciation, despite good appetite
- The loss of myelin sheaths surrounding the peripheral nerves. They become surrounded with fluid, and this leads to nerve damage in chronic cases.
- Rough, dry skin 
- Softening of brain tissue (encephalomalacia)
- Hepatic lipidosis and a decrease in white blood cell counts
- Embryo mortality and decreased hatchability
- Excessively long primary wing feathers with pigment alterations [10,21,23].
Vitamin B3 (Niacin/Nicotinic Acid)
Vitamin B3 (Niacin/Nicotinic Acid) is important for lowering the risk of cataracts, osteoarthritis, diabetes, and atherosclerosis, and it improves CNS integrity and general health. It is found in rice bran, cooked chicken breast, beef, greens, tomatoes, egg, kidney beans, brown rice, asparagus, fish, eggs, and mango .
Vitamin B3 Deficiency
Vitamin B3 Deficiency can cause poor feathering, nervousness, diarrhea, and stomatitis (inflammation of the mouth) .
Vitamin B5 (Pantothenic Acid)
Vitamin B5 (Pantothenic Acid) works to metabolize proteins, fats, and carbohydrates. It is involved in the formation of hormones, and, along with Vitamin A, protects and builds mucous membranes. When combined with Vitamin C, it aids in the production of 30 hormones (mostly sex hormones). It assists the building the body’s resistance to stress, aids in repairing physical damage, increases longevity, and works as an antioxidant to lower cholesterol levels .
Vitamin B5 Deficiency
Vitamin B5 Deficiency can cause:
- Poor body and feather growth; dermatitis (skin lesions) on the face and feet
- Reproductive disorders: retarded growth and early death in chicks, premature death of the embryo in the egg, and a decrease in natural hormone production
- Immune deficiency: Hypersensitivity to infections, a decrease in the white blood cell count, and a lower production of antibodies
- Vitamin B5 is found in meat, alfalfa, fish, molasses, rice, wheat bran, vegetables, cereal grains, legumes, eggs, and celery .
Vitamin B6 (Pyridoxine)
Vitamin B6 (Pyridoxine) is needed for amino acid metabolism; the breakdown of proteins, fats, and carbohydrates; adrenal function; metabolic processes; nervous system integrity; and cellular growth. It is found in cereals, buckwheat, beef, turkey, potatoes .
Vitamin B6 Deficiency
Vitamin B6 Deficiency causes:
- Ataxia, jerky, nervous walking, running, falling, flapping the wings, leading to death
- Scoliosis (abnormal curvature of the spine), caused by serum melatonin deficiency through continuous light exposure and deficiencies of copper and manganese
- Depressed appetite, poor growth, spasmodic convulsions, and decreased white blood cell counts in chicks; early embryonic mortality; suppressed immune function .
Figure 29. Severe arthritis in a cockatiel (image courtesy of Jeannine Miesle).
Vitamin B7 (Biotin)
Vitamin B7 (Biotin) is required for cell growth, the production of fatty acids, metabolism of fats and amino acids, maintaining blood-sugar levels, good feather production, and skin condition. It aids in treating skin conditions, heart disease, neurological disorders, and wounds. Mycotoxins (toxic mold) interfere with biotin uptake .
Hypovitaminosis B7 may cause:
- Exfoliative dermatitis or erythroderma (reddening of the skin), excessive scaling and throwing off of skin tissue on face, feet, and legs and swelling and ulceration of the foot pad, scaly dermatitis on the feet with scabs spreading to around the beak and eyes.
- Perosis in young birds; perosis is a deformity of the leg bones with enlargement of the hock, twisted metatarsi, and slipped tendons caused by deficiencies in biotin, manganese, and choline.
- Ataxia, reduced growth rates, poor feathering, white streaks and feather breakage.
- An increase in embryonic mortality and skeletal deformities in chicks
Treatment is with multivitamins to compensate for nutritional deficiencies. Vitamin B7 is found in meats, egg yolks, nuts, cauliflower, legumes, molasses, whole grains, beans, and fish .
Vitamin B9 (Folic Acid)
Folic Acid is important for the synthesis of amino acids and proteins, cell growth and metabolism, particularly Omega-3 fatty acid metabolism and CNS integrity .
Causes of Folic Acid Deficiency
- High levels of fat and low levels of methionine, choline, and Vitamin B12 in the food.
- Absence of animal-source ingredients in the food and intestinal bacterial overgrowth.
- Exocrine Pancreatic Insufficiency (insufficient fluid secretion in pancreatic duct) .
Folic Acid Deficiency
Folic acid deficiency in poultry can cause embryonic mortality, poor growth, and anemia; deformation of the maxilla (upper beak), bending of leg bones, and perosis. Antibiotic therapy, particularly with sulfonamides, could induce a deficiency .
Foods High in Folic Acid
Foods high in folic acid include citrus fruits, whole grains, green leafy vegetables, broccoli, asparagus, spinach, beans, and legumes.
Vitamin B12 (Cobalamin)
Vitamin B12 (cobalamin) is required for normal brain and nervous system functions and blood formation. Toxicity is rare and causes a change in the urine or urate color from white to yellow, brown, or orange/pink. Cobalamin is found in fish, meat, eggs, and poultry .
Vitamin C (Ascorbic Acid)
Vitamin C (ascorbic acid) is important for bones, connective tissues, muscles, and blood vessels. It aids in iron absorption and red blood cell production. It is synthesized in the liver and/or kidneys in seed-eating birds. Vitamin E and selenium deficiencies, heat stress, and parasitic infections increase the requirement and decrease production of Vitamin C. Debilitated birds have higher requirements and reduced ability to synthesize Vitamin C .
Vitamin C is important because it:
- Contributes to formation of collagen, a protein that gives structure to bones, connective tissue, cartilage, muscle, and blood vessels.
- Aids in iron absorption and red blood cell production. .
- Aids in alleviating stress; stressed birds require higher levels of Vitamin C.
- Is an antioxidant; it blocks tissue damage.
- Protects the epithelial tissues in the mouth from bacteria.
- Helps the white blood cells function and contributes to immune system integrity.
- Can decrease the duration and severity of respiratory symptoms.
- Accelerates wound healing and aids in collagen formation.
- Reduces mortality in growing birds by protecting the lymphoid organs and thyroid activity.
- Improves growth and egg production and is responsible for egg-shell thickness .
Vitamin C Deficiencies
Vitamin C deficiencies can result in:
- Heat stress, poor growth, poor eggshell strength and egg production.
- Fatigue, aching of the limbs, joint pain, easy bruising, and anemia.
- Failure to produce collagen, resulting in weak blood vessels, muscle tissue breakdown, and an inability to make scar tissue for proper healing of wounds .
Vitamin C Toxicity
Excesses of Vitamin C can result in:
- Growth deficiencies and hemochromatosis
- Aortic rupture and decreased elastin content of the aorta with copper deficiency .
Foods Containing Vitamin C
Vitamin C is present naturally in foods such as oranges, tomatoes, broccoli, green peppers, potatoes, and green leafy vegetables .
Vitamin D3 (Cholecalciferol or Toxiferol)
Vitamin D3 (cholecalciferol or toxiferol) regulates calcium and phosphorus metabolism, bone mineralization, and eggshell formation . It stimulates GI absorption and resorption of calcium and regulates the hormones controlling calcium and phosphorus (P) excretion in the kidneys. The sources are sunlight and supplementation. In birds that have a uropygial gland, D3 precursors are contained in the sebum that the birds express from the gland and spread on the feathers. The precursors are then activated by ultraviolet light. The sebum containing the vitamin is then consumed during preening activities. Some species do not have a uropygial gland; these and birds who are not exposed to UV light should receive supplementation. Many formulated foods exceed the levels suggested, so the owner should be careful about over-supplementation [23,27].
Hypovitaminosis D3 leads to:
- Skeletal/muscular disorders and pathological fractures due to Ca/P/D3 (calcium, phosphorus, vitamin D3) imbalances or magnesium deficiencies 
- Rickets. Without sufficient Ca/D3 there is not enough calcium present to harden the bones in growing birds. This occurs mainly in hand-reared birds whose mineral intake is unbalanced. It is also termed, "Rubbery Bone Syndrome" [19,23].
- Reproductive disorders
- Thin or soft-shelled eggs, poor egg production and hatchability, failure to pip, and embryonic death
- Renal failure in chicks
- Inadequate maternal transfer of Vitamin D3
- Poor beak development and abnormalities in chick development 
- Degenerative kidney disease, renal failure, calcification of renal tubules and arteries 
- Widespread calcification of soft tissue (articular gout and hardening of joints) 
- Visceral gout. Calcium is deposited in internal soft tissue, uric acid is deposited in the ureters [23,45].
Hypervitaminosis D3 may cause:
- Renal nephrosis with calcification of the renal tubules and arteries [23,45]
- Widespread calcification of soft tissue and visceral calcinosis (formation of calcium deposits in soft tissue), resulting in deposits of uric acid in the ureter [27,45]
- Visceral and articular gout 
- Abnormalities in chick development 
Vitamin E is a fat-soluble compound. It is important for skeletal strength and has antioxidant properties that are needed for strong immunity and healthy skin and eyes. It prevents rancidity and fatty-acid degeneration of foodstuffs, softening of brain tissue (encephalomalacia), and muscular dystrophy in chickens. It needs to be combined with selenium and amino acids .
Vitamin E and selenium deficiencies can lead to tremors, ataxia, incoordination, reluctance to walk, and recumbency. Supplementation with injectable and oral Vitamin E is advised, but survival depends on the severity of the illness .
Vitamin E, selenium, and calcium deficiencies also play a part in egg-binding and dystocia (difficulty passing the egg due to lack of muscle strength). Cockatiels, canaries, lovebirds and finches have the most difficulty with these conditions because of their small size [17,33].
Hypovitaminosis E (with Selenium)
Hypovitaminosis E (with selenium) is associated with:
- Oral paralysis and edema of subcutaneous tissues. It is a malabsorption syndrome secondary to giardiasis due to oil in the diet and dehydration.
- Muscular and skeletal dystrophy and degeneration of the muscle fibers in the breast and leg muscles. These are common in lutino cockatiels. Muscle fibrosis results in the loss of wing movement and a marked clamping of the wings to the underlying sternum, bringing the wings together at the front of the body.
- Spraddle legs and pododermatitis
- Persistent feather sheaths. The sheaths remain on the calamus and don’t detach.
- Parakeratosis (dry, scaly skin) caused by Vitamins E and B5 deficiencies. It is an abnormality of the epidermis, preventing keratin formation. Treatment is Vitamins B and E therapy and the elimination of any endoparasites.
- Brown, fatty pigment accumulation in liver cells and Fatty Liver Disease 
- Encephalomalacia caused by deficiencies, mostly in young birds. Symptoms include torticollis, crying out, excessive wing flapping while maintaining abnormal postures or "crazy chick disease" .
- Polyphagia (excessive hunger). The bird hulls the seeds and appears to be eating, but the crop remains empty. This occurs in very weak birds or those on a poor diet. .
- Poor immune response. B-complex vitamins and Vitamin E improve this condition.
- Muscular dystrophy of the heart, degeneration of ventricular musculature [6,23]
- Seizures, ataxia, and localized paralysis due to salt toxicity and low levels of thiamine, calcium, and Vitamin E 
- Hypothyroidism, leading to obesity, goiter, and retarded healing 
- Infertility, poor hatchability, egg binding, degeneration of the pipping muscle in neonates, and nestling deaths. It is caused by calcium, Vitamin E, and selenium deficiencies .
- Exudative diathesis. This is an oozing condition which lowers immunity. It is found mostly in chickens and hatchling budgerigars. Clinical signs are the pendulous appearance of the neck which, on palpation, feels soft. It is seen as a soft swelling of the neck. B-complex vitamins and Vitamin E improve these conditions [10,23].
Figure 30. Cockatiel chicks with splayed legs from hypovitaminosis E (image courtesy of Ellen in Maine; used with permission).
Hypervitaminosis E may lead to:
- Hardening of soft tissues (calcinosis), crop liths, and impaired bone mineralization
- Decreased absorption of Vitamins A, D, K, resulting in reduced liver function
- Coagulopathies (poor blood clotting)
- Impaired neuromuscular, vascular and reproductive systems .
Foods Containing Vitamin E
Vitamin E is found in soy, corn, olive oil, spinach, nuts, broccoli, squash, pumpkin, dark leafy greens, corn oil, soybean oil, margarine, and dressings with wheat germ oil, sunflower oil, or safflower oil. Nuts have insufficient Vitamin E, and the positive effects of Vitamin E are negated by polyunsaturated fatty acids .
Vitamin K (Phylloquinone, Phytomenadione, or Phytonadione)
Vitamin K (phylloquinone, phytomenadione, or phytonadione) is required for regulation of proteins and blood coagulation. It is required for synthesis of a protein required for blood clotting and is used to manage anticoagulant rodenticide intoxications. It is synthesized by plants, and bacterial flora in the intestine are its natural source .
Vitamin K Deficiency
Vitamin K deficiency results in delayed blood clotting and heavy hemorrhaging from minor injuries. Without it, birds may experience excessive bleeding and exsanguinate (bleed out) from minor injuries. Clotting is controlled by the liver, and toxicities result in kidney tubule degeneration. Antibiotics affect the bioavailability of Vitamin K. The vitamin supply should be increased when birds are receiving medical treatment or when breeding .
Foods Containing Vitamin K
Vitamin K can be found in broccoli, peas, beans, peppers, spinach, leafy greens, carrots, apples, cabbage, cauliflower, cereals, soybeans, whole wheat, oats, and bran.
Minerals are needed by the body for building bones, producing hormones, and regulating the heartbeat. Some minerals are common in foods, so deficiencies are rare in psittacines .
Sodium and Chloride
Sodium and chloride are macrominerals (minerals needed in large amounts). Microminerals are trace minerals, so only small amounts are needed. Sodium and chloride are usually found together in the source food. Birds do not require very much, but they do need some; most birds get sufficient sodium from their foods. Sodium and chloride are needed for “osmoregulation,” maintaining fluid and electrolyte balance. It is also needed for muscle relaxation, transmission of nerve signals, and blood pressure stability .
Sodium and Chloride Deficiency
In psittacines, sodium and chloride deficiency may cause:
- Skin and feather disorders, self-mutilation and corneal keratinization
- Gonadal inactivity and adrenal hypertrophy. Decreased adrenal function leads to increased blood uric acid levels which can result in shock and death.
- Reduced utilization of protein and carbohydrates; retarded growth in chicks, a decrease in blood volume, reduced egg production. Demineralized bone formation (soft bones) is often a result of ingesting mineral blocks.
- Central Nervous System signs: ataxia and hyperesthesia (oversensitivity to sensory stimulation); dehydration resulting in chicks falling forward with their feet stretched out behind them for several minutes
- Hemoconcentration: an increase in the concentration of blood cells resulting from blood loss and a decrease in cardiac output and blood pressure .
Sodium and Chloride Toxicity
The signs of sodium and chloride toxicity are: increased thirst, convulsions, muscle weakness .
Sources of Sodium and Chloride
Sodium and Chloride are found in table salt, soy sauce, processed foods, breads, unprocessed meats, fresh fruits and vegetables, whole grains, and legumes .
Figure 31. Sodium deficiency. A normal bird and a sodium-deficient bird at 4 months. Experimentally salt-deprived (on right) versus normally fed (on left) 3 week-old broiler chicks (image courtesy of H. Opitz; used with permission).
Potassium is needed for transmission of nerve signals, muscle contractions, fluid balance, and various chemical reactions. It is required for glucose and protein metabolism .
Potassium deficiency may cause excessive amounts of body fluids being excreted, leading to:
- Muscle weakness, general weakness, and ultimately failure of the respiratory muscles.
- Heart irregularities, cardiac arrest, and cardiac weakness.
- Decreased egg production, egg-shell thinning, tetanic (twitching) convulsions
- Poor intestinal tone with intestinal distention.
- Disorientation and eventually death .
Calcium is the most predominant mineral in a bird’s body. It is stored in the skeletal system and absorbed in the small intestine through diffusion . High-fat diets, antibiotics, and high phosphorus levels interfere with calcium uptake. During the reproductive cycle, a bird’s calcium and phosphorus levels fluctuate prior to and during egg-laying. Harmful calcium levels are actually only slightly higher than required levels. Seeds are low in calcium .
Calcium is required for:
- Myofibril (muscle fiber) contraction and transmission of nerve impulses [23,29]
- Normal metabolism, bone mineralization, and the permeability and excitability of cell membranes, formation, strength, and growth 
- Activation of enzyme systems, glandular secretions, blood coagulation 
- Reproduction. Additional calcium is needed for:
- Egg formation, shell calcification, uterine contractions, fertility, and hen health [23,29,35]
- Osteomyelosclerosis (buildup of calcium in the long bones, or ossification). This is mobilization of calcium from medullary bone in the marrow cavity of the long bones [35,45]. If the hen draws too much from her bones, they will become weak and fracture easily. Additional calcium needs to be provided for at least two weeks for every egg that is laid .
Figure 32. The X-ray on the left (A) displays a short, angular curve showing severe wedging at the apex with partial dislocation of a bone in a joint (subluxation) of one vertebra on another. The X-ray on the right (B) shows a smooth curve, indicative of scoliosis and osteomyelosclerosis. Calcium has been drawn from the bones, leaving the hen’s bones weakened (image courtesy of P. Macwhirter; used with permission ).
The Calcium-to-Phosphorus (Ca:P) Ratio and Diet
The dietary ratio of Ca:P should range from 1:1 to 2:1. High-phosphorus foods such as meats, Brazil nuts, pumpkin seeds, safflower and sunflower seeds should be minimized in the diet . Foods low in calcium include sweet corn, pumpkin, muscle meat, milo, oats, most seeds, fruits, vegetables, and pine nuts .
Calcium Deficiency or Incorrect Ratio of Ca/P/D3
A calcium deficiency or incorrect ratio of Ca/P/D3 can cause:
- Orthopedic disorders and metabolic bone diseases:
- Rickets in young birds and osteomalacia in mature birds, leading to softening and bending of bones 
- Tibiotarsal bone fractures, brittle bones, “cage paralysis” in chickens confined to cages for long periods of time, and bone distortion 
- Leg deformities, toe malposition, and leg paralysis in neonates. These are associated with calcium, chloride and riboflavin deficiencies [23,45].
- Decreased bone mineralization and abnormalities of the long bones and the vertebral column, particularly in growing birds [23,45].
- Skeletal abnormalities, defects of the growth plates, abnormal cartilage masses under the growth plates of the long bones, enlarged, painful joints. The bones become weak and porous until the weight of the bird or pull of the muscles creates bone deformities or fractures [23,45].
- .Beak demineralization and overgrowth; soft, flaky beak tissue (rubbery beak) due to insufficient Ca/D3 and methionine; hyperparathyroidism (overactive parathyroid glands); rapid growth from too much protein [3,22-24,45]
- "Angel wing" or "Airplane wing" is caused by imbalances of Ca/P/D3, too much protein, white bread, and too rapid growth. Heavy, blood-filled, developing flight feathers are being supported by non-rigid, inadequately mineralized bones in young waterfowl, leading to rotation of the distal wing tip. The primary flight feathers fan out at the elbow joint when the wings are folded against the body, making the bird flightless. Budgerigars, macaws, and conures are also prone to it [23,45].
Figure 33. Scissors beak in an Indian ring neck (image courtesy of Unusual Pet Vets, Australia; used with permission).
Figure 34. Angel wing in a Canadian goose (image courtesy of Operation Migration; used with permission).
- Neurological Disorders
- Hyperexcitability. Decrease in electrical resistance and an increase in the membrane permeability of nerve tissue allow the nerve tissues to absorb too much sodium and potassium .
- Weakness, ataxia, hyperesthesia, opisthotonos, seizures, episodic convulsions, head twitching, tonic extension of the limbs ; sometimes seen in African greys .
- Feather and Skin Abnormalities
- Dull, discolored, fragile plumage, poor feather condition, feather picking .
- Asymmetric feather loss, poor molting, non-uniform growth of the plumage, often related to egg-laying [24,33,45].
- Hyperparathyroidism: Too much parathyroid hormone in the body leads to kidney damage. High serum phosphorus levels interfere with calcium absorption, leading to an enlarged parathyroid gland . Symptoms are weakness, polydipsia, anorexia, and regurgitation. Decreased egg production, soft-shelled eggs, egg-binding and fragile bones occur in breeding hens [24,45].
- Hypocalcemic Tetany and Seizures: repeated, prolonged contraction of muscles, especially of the face and limbs, caused by low blood calcium due to an underactive parathyroid gland or Vitamin D deficiency. Birds have difficulty mobilizing calcium from body stores and need constant supplementation. Often seen in young African greys. Treatment is quickly effective [10,18,19,23,29].
- GI Disorders, including increased thirst, anorexia, and regurgitation. Treatment is supplemental calcium/D3 injections, improved diet .
- Respiratory Disorders. Dyspnea, shortness of breath, gaping, extended neck and wheezing associated with goiter and obstruction of respiratory passages or sinusitis .
- Reproductive disorders
- Soft-shelled eggs which can burst on exit and become retained resulting in internal infections and hen and embryo death; dystocia or metabolic bone disease [18,45].
- Delaying or decreased egg-laying due to reduced oviduct muscle activity 
- Egg-binding. Oral 10% calcium gluconate, along with other treatments, will help in the removal of the egg and may allow the bird to pass the egg naturally .
- Decreased bone density, especially in cockatiels [27,29].
Figure 35. Soft-shelled egg due to insufficient calcium (image courtesy of Tracey Alloway; used with permission).
Figure 36. Soft-shelled egg which split upon being laid by a cockatiel. This is due to insufficient calcium and other important minerals (image courtesy of Jeannine Miesle).
Figure 37. Egg-binding in cockatiel from insufficient calcium (image courtesy of Mike Owen; used with permission).
This leads to:
- Articular gout 
- Bone tumors from osteolysis (resorption of bone by the body) 
- Renal disease, dehydration, nephrosis, and soft-tissue mineralization 
- Elevated serum calcium and prolonged hypercalcemia 
- Decreased iron absorption and feather color changes in chicks 
- Lipemia (fat in the blood) associated with ovulation 
- Sandpaper-egg shells, abnormally thick, rough shells; the chick is unable to break through them, resulting in high chick mortality .
- Nervous system disorders: Hyperesthesia, opisthotonos, ataxia, episodic convulsions, head twitching or flicking, weakness, and muscle cramps .
Bone is the main storage organ for phosphorus. The requirement is highest during the time the animal is growing. It is needed for:
- Cellular metabolism and maintenance of acid-base balance, energy currency of the cell.
- Growth, skeletal development and bone formation, calcium transport in egg formation
- Fat and carbohydrate metabolism.
Phosphorus deficiency results in decreased egg production, poor eggshell quality, and rickets. Deficiencies are rare since it is common in most food items. Excess phosphorus leads to increased renal elimination of calcium .
Selenium and Vitamin E function synergistically as antioxidants in poultry, affecting whole blood levels. It is needed for growth, reproductive success, and for the production of thyroid hormones. It prevents ventricular myopathy, and exudative diathesis. It is important for exocrine pancreatic function and the production of thyroid hormones. Conditions caused by deficiency may sometimes be seen in psittacines since their physiology is very similar, but the link with selenium deficiency has not been established .
Selenium deficiency may cause:
- Alopecia (feather loss), poor feathering, and dermatitis
- Impaired fat digestion, exocrine pancreatic malfunction, and pancreatic atrophy
- Abnormal skeletal formation and muscle disease
- Diminished immune function and reduction in immune response
- Ventricular myopathy (weakness in the heart)
- Alterations to cell division and delayed sexual development
- Early embryonic death, fetal abnormalities, weak chicks, and retarded growth .
- With Vitamin E deficiency, "white muscle disease", which causes paralysis of the legs; this may be permanent; it is most often seen in cockatiels .
Selenium toxicity may result in decreased hatchability, deformed embryos, emaciation, and liver lesions. Selenium is found in wheat, egg yolk, pasta, ham, beefsteak, grains .
Zinc is Needed for:
- Formation of glucagon, formation of insulin, and proper functioning of vitamin A 
- Enzyme metabolism, appetite regulation, and cell replication 
- Growth and development of cartilage and bone, feathering and molting
- Eye health, particularly in older birds [24,30].
Zinc deficiency results in:
- Short, thickened long bones and enlargement of the hock in poultry
- Dermatitis, pododermatitis, and sepsis (blood infection)
- Impaired T-cell function [23,30]
Zinc toxicity usually arises from ingestion of zinc-coated aviary wire or metallic foreign bodies, often from new cages containing galvanized wire or hardware . Small metal bells on toys are often coated with zinc, particularly those made in countries other than the USA.
Clinical Signs of Toxicity
- Nerve dystrophy and neurological signs
- Perosis, due to deficiencies in manganese, biotin, pantothenic or folic acid
- Anorexia, ataxia, paresis (partial loss of movement), and lethargy
- Acute gastroenteritis; yellow, bright green, or dark feces
- Diarrhea, vomiting and passing of blood in the feces
- Extreme loss of plumage and feather-damaging behavior
- Pallor of the oropharynx
- Pancreatic cell necrosis, hepatomegaly, and sudden death
Treatment includes increased exercise and a low-mineral diet, or possibly surgery .
Figure 38. Heavy Metal toxicity (image courtesy of Julie Burge; used with permission).
Birds require very little iron. It is needed for the production of hemoglobin and many enzymes, proper feather pigmentation, and oxygen transport from the lungs to the rest of the body .
Iron deficiency results in anemia due to low levels of red blood cells and hemoglobin. Treatment is high protein, high-energy diet with B-complex vitamins. Iron is in fruits, vegetables, whole grains, lean meats, fish, beans, eggs, nuts, spinach, soybeans, and lentils .
Iron toxicity results in:
- Hemochromatosis: an abnormal accumulation of iron in the liver, heart and spleen leading to liver toxicity due to the body’s inability to eliminate excess iron 
- Ascites, causing swelling and damage to the liver, spleen, and heart [16,23]
- Dyspnea, distension, coughing, anorexia, weight loss, depression, and biliverdinuria (green bile in the droppings) 
- Endocrine and neurological disorders, infection or neoplasia .
- Birds should be on low-protein, low-iron diets which have a high biologic value, such as hard-cooked egg, cooked white meat of chicken .
Manganese works closely with calcium and zinc and is needed for normal bone and egg-shell formation, growth, reproduction, skin integrity, and sugar control. It is found in nuts, legumes, seeds, whole grains, and leafy green vegetables 
Manganese deficiency may be due to an excess of calcium and deficiencies of choline, biotin, and zinc in the diet. Seeds are deficient in manganese. Deficiency may result in:
- Ataxia and retarded development of down feathers 
- Retarded growth, thin-shelled eggs, poor hatchability 
- Perosis. The birds are crippled and usually die of starvation. In poultry, young birds develop short, thickened limbs, a parrot beak, and a protruding abdomen 
- Luxation (dislocation) of the tarsometatarsal (lower leg) joints and rotation of the intertarsal joints (bones in the foot), preventing normal use of the limb 
- Chondrodystrophy (skeletal disorder affecting the development of cartilage). The bird has shortened, thickened legs and shortened wings 
- Mandibular prognathism: The maxilla rests inside the mandible due to a disproportionate shortening of the lower mandible 
Figure 39. Mandibular prognathism (image courtesy of Melanie Canatella; used with permission).
Manganese toxicity results in decreased hemoglobin, anemia, renal failure, and poor growth .
Copper is stored in the bones and is needed for iron synthesis, healthy blood vessels, bones, and connective tissue. It is an important component of several enzymes. Very little is required. Foods containing copper are potatoes, butter, lentils, barley, beans, wheat, and kale .
Copper deficiency could result in:
- Impaired feather pigmentation. Deficiency interferes with melanin production and causes dark-colored feathers to become lighter.
- Deficiencies in essential amino acids which form keratin
- Aortic rupture and bone fragility
- Egg production and shell abnormalities in poultry: shell-less, misshapen, wrinkled eggs, and large eggs with thin shells 
Magnesium is present naturally in many foods. It is needed for bone formation, heart health, carbohydrate metabolism, and enzyme activation. Deficiencies result in poor growth, lethargy, convulsions, and death. Toxicity signs are diarrhea, irritability, decreased egg production and thin-shelled eggs .
Iodine is used to treat thyroid goiter . Deficiency is a result of insufficient thyroxine production by the thyroid gland. Treatment is iodine supplement and Thyrosyn .
Iodine deficiency may cause:
- Hypothyroidism, leading to obesity, lipomas, slow growth, and CNS signs [19,23]
- Elongated Down Feather Syndrome: Down feathers overgrow and extend out from the body.
- Changes in molting and feather structure .
- Goiter, causing voice change or loss, They develop in birds fed all-seed diets lacking vitamin/ mineral supplementation. Clinical signs develop secondary to compression of the trachea and/or crop by the enlarged thyroid gland. This causes a "thoracic click" (a respiratory sound), dyspnea, and possible regurgitation .
Figure 40. A macaw with goiter (image courtesy of Chuck Wendig; used with permission).
Figure 41. Elongated down feathers from iodine and riboflavin deficiencies (image courtesy of Adorjan Hanna; used with permission).
Iodine toxicity is rare in birds; it is caused by misuse of disinfectants that contain iodine or over-supplementation of iodine. Excess iodine interferes with normal thyroid gland function, particularly in young birds. Toxicity leads to:
- Poor growth and reduced food intake
- Central Nervous System signs
- Reproductive issues
- Poor sexual maturation in male and female fowl and decreased male fertility due to dead spermatozoa
- Incorrect hatching of fertile eggs, extended hatching time, embryonic mortality, and dead-in-shell chicks
Reproductive issues return to normal within seven days of feeding normal iodine levels .
Choline is essential for:
- The building and maintenance of cell structures and fat metabolism in the liver
- Normal maturation of the cartilage matrix of bone and growth; prevention of perosis
- Formation of eggs
- Wing and tail feather pigmentation
- Transmission of impulses along the sympathetic nervous system .
11. Other Required Nutrients : Proteins
Protein is an energy source composed of nitrogen-containing molecules and amino acids. The larger the species, the higher the requirements. Essential amino acids cannot be manufactured by the body and must be included in the diet. They build body tissue and regulate the chemical reactions that keep the bird’s body growing and functioning [14,29].
- Feather formation: feathers comprise 20% of the total body protein requirements in birds
- Bone growth, muscle integrity, and enzyme production
- Hormone production, especially in laying hens; growth in chicks 
- Molting, which takes 8-10 months in captive psittacines; malnourished birds take longer
- Provision of insulation to maintain warmth in birds with poor feathering [28,29].
Protein deficiency may cause:
- Hepatic lipidosis and gout. Malnutrition and choline deficiency inhibit the transport of protein. This forces the liver to retain the fat that it manufactures 
- Cessation of ovulation and reduced egg production 
- Stunting, poor growth and development, and high mortality in chicks [23,29]
- Obesity. Birds on decreased protein levels increase their food intake in order to compensate for protein deficiency; they gain weight from excessive body fat [23,29]
- Anemia. Protein and the B vitamins are needed for prevention .
High Serum Protein Levels (Hyperproteinemia)
High serum protein levels (hyperproteinemia) may cause:
- Regurgitation, rejection of food, and weight loss, particularly in cockatiels 
- Neurological signs and behavioral changes: aggressiveness, biting, nervousness 
- Poor growth rates, overgrown beak and nails, and increased susceptibility to disease 
- Renal dysfunction, nephritis (inflamed kidneys), and dehydration 
- Gout, caused by high levels of protein/Ca/D3. Psittacines excrete uric acid as the chief component of nitrogenous waste (the urates), so excessive intake of proteins or nucleic acids may lead to excess uric acid in the blood which interferes with the kidneys’ ability to excrete the uric acid. Excess uric acid is then stored in the viscera or joints [23,24].
Treatment for Protein Toxicity
- A low-protein diet to decrease the workload of the kidneys
- Energy sources other than protein, such as fruits and vegetables and a small amount of pellets
- Vitamin A for proper functioning of the mucous membranes lining the ureters
- Increased B vitamins to compensate for the loss of body fluids
- Lower amounts of Ca/P/D3, magnesium, and sodium to avoid renal mineralization .
11.1.5 Protein Sources
Protein sources are white meat of poultry and pork, cheese, eggs, beans, soy, seafood, beef roast, tenderloin, steak. Offer red meat in very small amounts and occasionally .
12. Essential Fatty Acids (EFA’s) and Amino Acids
Amino acids and proteins are the building blocks of life. They are organic compounds that combine to form proteins, and protein is broken down into component amino acids before being absorbed by the intestines [23,27]. Amino acids are required for optimal health, but the body cannot synthesize them; they must be provided in foods or supplements. The terms, “EFA’s” and “amino acids” are used interchangeably. EFA’s refer to the Omega-3, 6 and 9 fatty acids. Most hand-rearing mixes for psittacines and pelleted diets lack sufficient quantities of the sulphur amino acids (methionine and cysteine) [18,23].
Omega 3 and 6 fatty acids are polyunsaturated and rich in linoleic acid. Linoleic, methionine and cysteine have anti-inflammatory, anti-neoplastic, lipid-stabilizing, and renal-protective properties. They also possess antibacterial, antifungal, and antiviral properties to ward off pathogens [14,40]. EFA’s reduce mortality rates in chickens and allow birds to maintain their body weight .
Essential Amino Acids for Birds 
The essential amino acids for birds are:
Supplementation with Omega-3 Fatty Acids
Supplementation with omega-3 fatty acids improves:
- Bone health, improved immune system, increased antibody responses in poultry [14,32]
- Neurological development in poultry. Increased cognitive ability and higher concentration were found in chicks whose parents were fed high amounts 
- Neonatal brain health and the risk of heart and cardiovascular disease [13,32]
- The risk of cancer; increased survival time and quality of life 
- The risk of ovarian cancer and reduced mortality in laying hens 
- Weight management and overall health with flax seed 
- Renal function and decreased progression of some kidney diseases 
- The risk of obesity with lower fat-pad masses and reduced overall body-fat mass 
- Feather picking and arthritis by reducing inflammatory responses .
Key Points about Amino Acids
- Methionine, cysteine, and lysine are needed for feather integrity; deficiencies lead to achromatosis (color changes) on the wings and tails of dark-colored birds [1,29]
- Omega-3 fatty acids:
- Supply energy and facilitate the absorption of fat-soluble vitamins
- Are precursors of many hormones and aid in mediating inflammation
- Form cells and membranes and regulate cell functions 
Figure 42. Stunted feather growth and retained feather sheath (image courtesy of Mary Souder, used with permission).
Figure 43. Stress lines on feathers (image courtesy of Bird Tricks; used with permission).
Deficiency in Omega-3 and 6 Fatty Acids
A deficiency in Omega-3 and 6 Fatty Acids, particularly linoleic acid, is associated with:
- Reproductive difficulties, embryonic death, poor hatchability, and poor growth
- Hepatomegaly, from accumulation of liver fats, leading to hepatic lipidosis
- Obesity, decreased metabolic efficiency and a weak immune system
- Diarrhea and poor absorption of other nutrients, such as calcium 
- Malocclusion and other beak deformities 
- Oily feather textures, feather curvature, restriction of the rachis (feather shaft) [1,23,27]
- Wing feathers curled upward from lack of contour feathers and arginine deficiency [23,27]
- Stunted feather growth, retained feather sheaths, misshapen vanes; stress lines [1,27]
- Excesses cause soft, weak feathers, weak pin feathers, stunted feather growth [23,28].
Sources of Amino Acids
- Fish, flaxseed, canola oil, green leafy vegetables, walnuts, kiwi, cereal, black-eyed peas, spinach, pineapple juice, beef, soy beans, cauliflower, nuts, squash, broccoli, beans, cheese, beef, poultry, dried beans, eggs, seafood, some breads, rice and pasta .
- Vetomega, a liquid Omega-3, 6, 9 supplement. It comes highly recommended by avian veterinarians and can be obtained from your avian veterinarian.
In a normal companion bird’s environment, its diet is its primary link to health and longevity. It is imperative that the caregiver pay very close attention to the quantity and quality of the food he or she provides. Birds need a wide variety of foods, and fresh foods need to be prepared daily with particular attention to hygiene. Even the best diet requires the addition of a quality vitamin and mineral supplement to keep birds at optimum health, unless the bird consumes a large quantity of pellets.
1. Altman R, Forbes N. Self-assessment Color Review of Avian Medicine. Iowa State University Press/Ames, 1998. p. 78, 182
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Affiliation of the authors at the time of publication
West Chester, OH, USA.