Twenty Years of Progress in Pet Bird Nutrition
Published in JAVMA vol 212, No 8, April 15 1998 p1226-1230 reprinted
with permission of AVMA
Greg J. Harrison, DVM, Dipl. ABVP - Avian Practice
The Bird Hospital
5770 Lake Worth Road
Lake Worth, FL 33463
561-964-2121 fax 561-433-3521
BirdDoc@aol.com
For much of the last twenty years, avian veterinarians have been occupied with developing diagnostic and
therapeutic procedures for companion birds. Birds have often been presented in an emergency condition, and
many of these birds died. In the late 70's, the most conspicuous causes were related to importation (eg,
infectious diseases, parasites, immunosuppression from overuse of antibiotics) or poor management
associated with companion bird breeding facilities. Veterinarians were concerned about putting out these
disease "fires," so preventive medicine was not much of a consideration.
At the same time, however, Dr. Milton Scott of Cornell University was exploring avian diets. Dr. Scott
conducted whole body analyses of birds, which showed that across the orders, all birds were made up of
very similar components (especially ash and protein). He concluded that variation in actual intake of
foodstuffs was primarily a result of food availability and adaptations for harvesting. Recommendations were
made at that time regarding nutrient requirements of birds.
Today, twenty years later, many advances have occurred in the medical and surgical care of companion
birds; therefore, one would think that enormous strides have also been made in pet bird nutrition. But
relatively little scientific research has been conducted. According to experienced avian practitioners,
malnutrition still underlies up to 90% of all clinical cases, yet veterinarians continue to recommend
inappropriate diets for birds, including the feeding of enormous amounts of table food and the combining of
various commercial products together (in effect, allowing the client to become his own "nutritionist"). Pet
shops are also relatively ignorant about bird care and allow economics to dictate their sales of "bird food"
(seed) to the public.
There will probably never be documented nutritional requirements for all the species of psittacine birds
commonly kept as pets. But the knowledge is there for today's avian professional to prevent malnutrition by
offering to species under their care practical diets based on the considerable data available for Galliformes,
Anseriformes and Passeriformes, and to evaluate and re-evaluate the clinical results obtained from feeding
trials with various formulations. The variables that must be considered in applying the limited formulas that
have been developed include: the species, age, sex, genetics, season of the year, housing, activity level, and
whether the birds are laying eggs, raising young, molting, or recovering from surgery, disease or other major
stress.
Many veterinarians with private bird clients and large collections of birds with malnutritional diseases often fail
to realize the progress made by manufactured diets in recent years. It has become obvious from observing
birds undergoing a diet change to a high quality formulation that a transformation occurs in the behavioral
aspects of the bird as well as the physical and physiological condition.
I. AVIAN FEEDING RECOMMENDATIONS 1977-1997
Seeds
According to the September, 1997 issue of Pet Age Magazine, the top four bird food companies in the
United States base their sales mainly on seeds; therefore, most companion birds in this country are eating
seed-based diets -- just as they were in 1977. The difference is that today it is well known that seeds -- no
matter how they are colored, mixed or pressed into shapes -- are not a complete and nourishing diet for pet
birds. As early as 1923, scientists observed health deficiencies in caged parrots fed seed diets. Seeds
(cereal grains such as sunflower, millet, oats, safflower, corn) are missing essential nutrients for bird health
(Table 1).
Table 1. Deficiencies of Seeds
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Vitamins
choline, niacin, biotin (H), pantothenic acid, riboflavin (B2), vitamin A, vitamin D3, vitamin E,
vitamin K, folic acid (M), cyanocobalamin (B12)
Minerals
calcium, phosphorus (70% as phytates), sodium, magnesium
Trace minerals selenium, iron, copper, zinc, manganese, iodine, chromium, vanadium, bismuth, tin,
boron
Pigments
chlorophyll, carotenoids, canthaxanthia
Protein (amino acids)
Fiber
lysine, methionine
soluble (mucopolysaccharide), insoluble
Vitamin precursors
beta carotene
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Pet birds are reluctant to give up a seed diet for several reasons: 1) their parents were probably raised on
seeds; 2) birds are extremely habitual creatures and do not want to change; 3) seeds are relatively high in
fat content and thus taste good. On the other hand, if a bird had been raised on a formulated diet, it would
not recognize seeds as food and would be reluctant to eat them.
Seeds Plus Supplements
As birds became more popular as pets in the early 1980s, improper feeding was identified as the chief cause
of disease and death in pet birds. It was accepted by then that seeds had deficiencies of nutrients so the
term "malnutrition" was considered synonymous with "deficiency." The "cure" was perceived to be the
addition of supplements to the seed diet.
The first supplements consisted of liquid vitamins applied to the drinking water, which was eventually
discounted because of the dilution, pollution and rejection by the bird. Similarly, a cuttlebone attached to the
side of the cage did not replace the missing calcium. Soon manufacturers of seed diets claimed to have
various topical applications or secret processes of nutrients that penetrated the hulls of seeds to render the
kernel "balanced" when consumed. None of these -- including colored seeds, vitaminized seeds, fortified
seeds, pressed and glued seeds -- appeared to be effective because the clinical signs of malnutrition were
still evident.
Table Foods
The next step was to supplement with fresh table foods -- the wider the variety, the better -- eventually
evolving to recommendations of dark green, leafy and dark yellow vegetables and fruits because of their
vitamin precursor content. Owner compliance was high because feeding their bird from the table was an
excellent opportunity for bonding. Publications on "how to make your bird a table food connoisseur" implied
that these steps would result in a balanced diet. What resulted were inconsistent feeding practices and
basically allowing the bird to "choose" its own diet.
Even the fruits and vegetables that are available on the market today in the USA do not contain high quality
nutrients -- they are often picked immature in order to be shipped around the world (as many are imported
from Central America, Mexico and even Australia), some are chemically treated to resemble mature
vegetables, and most are grown with non-sustainable agriculture practices. The actual nutrient levels in the
soil in the United States have been dropping since the 1930s because there is seldom correct crop rotation,
fertilizers are limited to only nitrogen, phosphorous and potassium, and there is no composting or trace
mineral replacement.
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Table 2. Overview of 20 Years of Recommendations for Feeding Pet Birds
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1970s -
seeds, grit, cuttlebone, greens, liquid vitamins, turkey food, dog food, trout chow, canary
seed, lory diets, flamingo diets, early pelleted products, monkey biscuit, bread, milk, fruits,
meat, chicken starter, vegetables, nuts, eggs
1980s -
dog food, variety seeds, nuts, fruits, vegetables, oyster shell, sprouts, egg shells, mynah bird
pellets, trout chow, bread, wheat germ, insects, cuttlebone, pound cake, multivitamins,
soybeans, bean mixes (with or without dog food), monkey biscuit, turkey pellets, mash,
pellet, kibble or crumble, mixed animal pellets (pig, monkey, turkey, pigeon, rabbit, mouse,
hamster), fruit, sprouts (and then no sprouts), table food, egg, bread, pellets, cooked beans,
peanut butter
1990s - well developed formulated, pelleted and extruded diets leaning toward "natural" ingredients and even
certified organic bird foods are available, but professionals continue to recommend seeds
and supplements or treats, rice, pasta, cereals, vegetable, fruits, meat, legumes, dairy
products, bones, pellets, cooked mixes, breads, muffins
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III. MANUFACTURED BIRD DIETS
Manufactured diets specifically for birds were developed first from poultry nutritional requirements. The initial
nutritional research performed on psittacines was done on cockatiels at the University of California at Davis,
looking superficially at a sustainable diet, then more specifically at hand-raising formulas and levels of protein,
lysine and total solids. Energy levels have been studied in research with budgies. The bulk of the data used
to design food for today's companion birds came from this background, starting with poultry and game bird
foods and modifying them based on feeding trials.
It is evident that manufactured diets have the most potential for providing apparent nutritional needs to pet
birds, but currently there are no published standards that would allow manufacturers to state that their foods
are "complete and balanced."
Early Manufactured Foods
The earliest attempts to adapt companion birds to manufactured diets relied on available formulas for other
species: trout chow, chicken starter, turkey chow, and eventually monkey chow because the primate diet
contained vitamin D3 rather than D2. During the 1980s large numbers of psittacine species offspring were
hand-fed using a monkey biscuit-based formula -- sometimes with added baby cereal to dilute the D3 levels
and peanut butter to increase the fat.
Pellets
Today's formulated diets were actually available in the form of pellets in 1977 but they were not very popular.
The concept was valid but the process of pelletization did not really cook the food and caramelize the
carbohydrates to increase the palatability. There was also some controversy over the effect of pelletization on
nutrients such as fatty acids. More importantly, the poultry formulations were too high in salt, vitamins A and
D3 and protein resulting in serious disorders in parrots.
Formulated Diets
Formulated diets increased in popularity in the late 1980s because of a process called extrusion. With
extrusion, ingredients are forced through a valve under high pressure and heat, resulting in a product with
uniform appearance, increased palatability from caramelized carbohydrates and incorporated air, increased
digestibility, and increased shelf life due to altered enzymes.
A number of well developed, high quality formulated diets are available today based on direct feeding trials
with various companion bird species. Some are more readily accepted than others. Birds are able to taste,
which is supported by the presence of taste receptors. Preference testing experiments have shown responses
to sweet, bitter, acid and salt solutions. Sugar or fat can be added to a diet to facilitate its acceptance;
however, the continued use of 10% sugar and 15% fat by weight in a formulated diet has been shown by this
author to be detrimental.
Subtle shades of black, brown, yellow and green (naturally occurring colors of food) have been shown to be
most acceptable by birds. The use of dyed foods has been found to decrease the acceptance of food by the
bird in several studies, although the owner may find these attractive.
The Fallacy of Balancing a Diet at Home
Recent work at the Animal Medical Center in New York verifies that adding table foods or formulated diets to
seeds does not balance a bird's diet; formulated diets must be fed over 75% of the total intake to be
effective. There are too many variables on the part of what the owner offers and what the bird selects.
Balancing the seed portion with an extruded or pelleted portion is also impossible to manage.
Nutritional Excesses
Documented cases of hypervitaminosis A and D3 are well known in pet bird literature. Yet to maintain the
level of nutrients consist with package labels to survive the production process and to prolong shelf life, some
manufacturers double or triple the initial amount of potentially toxic component. Heat- and moisture-sensitive
ingredients such as vitamins, vitamin precursors and pigments (eg, beta carotene) should be applied after the
extrusion or pelletizing process, in this author's opinion.
III. EVALUATING AN AVIAN DIET
One of the most important aspects of preventive avian care is nutrition. Many veterinarians do not realize that
malnutrition is the underlying cause of most of the clinical signs of disease they see on a daily basis. The
clinician should maximize his ability to detect the early signs of malnutrition because these are also the early
signs of illness. The chronic signs of malnutrition (feather picking, sore feet, dry, flaky skin, liver disease,
obesity, listlessness, lack of singing, talking and playing, chewing up cage, biting people, self-mutilation, etc.)
could actually be considered signs of cruelty. Especially when there are high quality formulated diets that
have proven to relieve these often painful clinical signs with no other form of therapy.
Clinical Signs of Malnutrition
Malnutrition can be the primary etiology that produces obesity, generalized deficiency syndrome,
hyperkeratosis, metaplasia resulting in poor feathering and skin quality, fatty liver degeneration, hypocalcemia,
gout, mineralization of kidneys, and other organ failure from dietary excesses. More often, though,
malnutrition creates an immunosuppressed bird that expresses this condition as feather picking, persistent
molting, cloacal prolapse, egg binding, chronic egg laying, foreign body consumption, behavioral problems,
and susceptibility to bacterial, yeast, viral and parasitic infections. These are the most common clinical
presentations seen in a psittacine practice and correction of these disorders becomes a major part of the
clinical criteria for evaluating the nutritional status of avian patients.
Physical Examination
A thorough, standardized physical examination is the single most important tool for evaluating the
bird's overall state of health, nutritional status and for monitoring corrections to the diet.
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Table 3. Clinical Signs of Malnutrition
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Skin hyperkeratosis, flaky, dry, itchy, loss of elasticity, easily torn, slow to heal,
excessive bleeding
Bottom of feet worn smooth with no scale pattern followed by ulceration
and painful bumblefoot
Wing, leg, tail membranes - thin, easily torn areas of stretch, tearing and picking
Uropygial gland swollen
Feathers general loss of feather quality: thin and unable to "open up" because of retained
sheaths; constant presence of pin feathers from frequent molts; "worn out"
looking from infrequent molts; saw-toothed edges; broken, bent, missing or
malcolored (usually black in blue, red or green feathers); feather picking and
consumption
Beak grows excessively long and has layered, horny material on top
Muscles poor tone and conditioning; inability to bite hard or crack seeds in
cockatiels
Cloaca commonly crusted, flaccid and easily prolapsed
Behavior irritable, inactive; excessive chewing on wood, plants, toys,
grit, leading to potential foreign body consumption; overeating, overdrinking;
constant regurgitation; less talking and playing; biting or chewing of self, others.
Body conformation - obesity, presence of lipomas, lack of body fat on low fat
diet
Nails require constant trimming or become excessively long and may curl.
Eyes discharge, nonresponsive eye blink, liths in lacrimal ducts.
Nares discoloration or stickiness in the feathers over the nares, liths in rhinal
cavity, hemocult positive
Urine - biliverdinuria, polyuria, polydipsia and often hyperuricemia
Gram's stain of feces - predictable change in quantity and quality of bacteria represented; trend is
toward low total counts consisting of high percent gram-positive rods, low grampositive cocci, then gram-negatives and yeast
Immune system depressed; birds more susceptible to bacterial, viral, yeast,
parasitic infections
Radiographic evaluation of organs - reduced liver shadow in low fat cases which is enlarged on
high
fat diets with a corresponding passive response of air sac mass
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Fecal Gram's Stain
A Gram's stain of the feces is highly meaningful in psittacines because the intestinal microenvironment responds to modifications in feeding and other husbandry practices by consistent,
predictable and measurable changes in bacterial variety and quantity. A healthy bird has primarily
gram-positive bacteria only and low to none gram-negative bacteria and yeast.
Evaluating a Pet Bird Diet
It is important to monitor the clinical signs of malnutrition and the expected changes seen as a
result of feeding a new formulated diet. Birds that do not conform to the expectations on
formulated diets can be reevaluated and small modifications made to individualize their diets for
optimum results. If this fails more extensive diagnostic work is indicated. Specific diets (low iron
for hemachromatosis-susceptible birds, for example) may be warranted. Some specialized diets
for various clinical syndromes are showing promise in some situations.
The practitioner must become familiar with preconditioning of birds for diet changes, recognizing
species that have difficulty in changing their diet and incorporating ideas for overcoming client
reluctance. Nutritional therapy is a necessary component for the therapy of all conditions in Table
3 and for most avian illnesses in general.
Evaluating an Aviculture Diet
The criteria for evaluating an avicultural diet, in addition to general health of the parents, include:
number of eggs laid, percent of fertile eggs, number of eggs hatched, number of surviving chicks,
incidence of problems in young (bent beak, bent legs, crop-emptying problems, failure to thrive,
slow weight gain, improper body/weight proportions, improper feather development/color/stress
lines, crying, gram-negative/yeast infections and death). Early results suggest formulated diets
and very limited amounts of seeds, nuts, fruits and vegetables to be the ideal breeding diet,
although this program lacks scientific documentation.
Refining Formulated Diets
Formulated diets will continue to be refined as new clinical and scientific data are generated. Well
informed and experienced avian practitioners are able to make minor adjustments in the clinical
use of these formulations.
Following Manufacturer's Directions
In order for formulated diets to provide optimum results, the directions for feeding must be
reinforced by the veterinarian to the client. Some examples follow:
1. Buy food fresh every 4-6 weeks and store in a cool environment. Smell and taste for freshness
often. Freeze product for storage longer than six weeks.
2. Feed fresh food daily. Because light, moisture and heat affect the freshness of all formulated
products, insist that the owner places only "fresh" food in the food bowl daily. (Many bird owners
accustomed to feeding seeds are used to "blowing and topping off.")
3. Avoid over-feeding. This is especially important with a product whose components are not
consistent in appearance -- the bird will selectively consume some and reject others.
4. Avoid over-supplementation. Most manufacturers recommend their diet to be fed in excess of
90% total intake with less than 10% supplements.
5. Restrict supplements to products that would correct possible imbalances and not stimulate
breeding. For example, fresh yellow or orange meaty fruits and vegetables and green leafy
vegetables. If the diet is organic, the supplements should also be organic.
6. For pet birds, avoid supplements that stimulate nesting and breeding activity in a pet bird.
These would include high-fat seeds and nuts or high-sugar carbohydrates (fresh sweet corn,
apples, grapes).
Formula Variations
The research has not been done to confirm the differences in dietary requirements among pet bird
species, but there are some. And the alert avian veterinarian will be able to determine from feeding
trials, experience and physical examination what adjustments need to be done to "basic"
formulas. Higher quantities of fat and protein but lower levels of calcium and vitamins A and D 3
may be beneficial to some Moluccan and Palm cockatoos, Queen of Bavaria conures, African grey
parrots, and many macaws, for example.
Age is also a variable: young birds in rapid growth stages require richer "production-type" diets. A
new and rapidly growing group - the aging or geriatric bird -- requires modifications to normal
maintenance formulas.
Nonchemical Components
There is evidence to suggest that birds are attracted to food without chemical substances. They
have been shown to avoid foods treated with pesticides if given a choice, for example. Artificial
colors, flavors and preservatives are potential toxins. Birds eating organic foods appear to have
noticeably less feather picking, bacterial and yeast infections, and improvement in liver problems.
The quality of the ingredients of the formulation must play a role in the nutritional results.
Products normally considered "safe" for animal food such as renderings or fish meal may not be
suitable for companion bird foods. Poultry foods developed for an animal whose life is defined in
terms of weeks does not seem appropriate for birds that should live 50 years.
Sustainable Agriculture
From the standpoint of farming, organic family farms tend to be small and are more concerned
with sustainable agriculture. These practices require crop rotation, control of pests by
encouraging predatory species in crop rows, restoration of humus and soil fiber in order to reduce
irrigation and restore a healthy "live" bacterial population. In the long term, organic farming is an
absolute necessity for the Midwest and other locales to control water run-off and replenish the
aquifer. Well water in many parts of the world is already unsafe for human consumption because
of ground water contamination with pesticides. A recent HBO special on breast cancer, called
"Rachel's Daughters," leaves little doubt for the need of organic food sources for humans.
IV. AVIAN PREVENTIVE MEDICINE
Practical Diet Change
Converting the bird to a well developed formulated diet is an important step in malnutritional
therapy and may require a specific plan to encourage the bird to accept a diet change. If the
client's bird is relatively young and robust and the client cooperative, this process can be
accomplished in the home. Some recalcitrant birds can be admitted to the veterinary clinic where
a new environment, daily weights and tube-feeding (if necessary) will facilitate the conversion.
The veterinarian must realize that most birds have been on seeds for awhile and are marginally, if
not seriously, malnourished, so the diet must be changed with minimal stress.
Results of Proper Feeding
Some consequences may occur following a diet change that may not be perceived by the owner
as positive. As the epithelium starts to heal, the bird may begin peeling, flaking, picking, molting
or sneezing, so these behaviors need to be explained by the veterinarian as temporary,
intermediate steps to a total restoration. Frequent misting with water may help soothe the tissues
as well as some holistic remedies.
Ultimately, proper feeding results in lower incidence of disease, faster response to therapy when
disease does occur, and increased production in breeding birds. Beneficial results are seen in
avian patients with maladies such as feather picking, fatty liver, black feathers or other malcolored
feathers associated with various liver dysfunctions, proventricular dilatation (macaw wasting),
prolapsed cloaca, egg binding, chronic egg laying, foreign body consumption, objectionable
personalities, general need for surgery, bacterial, yeast and apparent viral infections. Better
housing and the curtailing of importation have also contributed to improved medicine.
Transformation to Avian Preventive Practice
Now that well developed formulated diets for birds are available, there is a transformation in bird
care, not only in the appearance and behavior of companion birds but in their resistance to
diseases, their response to treatment, their ability to heal quickly following surgery and their
ability to regain their normal reproductive activity. Most importantly, the malnutritional conditions
are seldom if ever seen.
Of course, malnutrition is not the sole etiology of illness in companion birds, but because it is
finally recognized as a preventable disease, the avian patient may now be given the opportunity to
develop systemic health and to live a longer, more enjoyable and significant life. Equally
important, it permits the veterinarian the pleasure and rewards of practicing preventive medicine
in companion birds.
Modifications will be made in feeding practices for pet birds as controlled studies are performed,
but as M. Murphy points out in Avian Energetics and Nutritional Ecology: "Satisfactory criteria for
accurately qualifying the nutrient requirements of animals remain elusive. Our study of avian
nutrition derives from domestic bird studies whose selection for nutrient reserves has been
relaxed for generations while wild animals have phenotypic and genotypic plasticity in their
metabolism, physiology and behavior. It seems reasonable to suggest...the study...(be)...focused
on this plasticity...and...nutrient requirements should be designed mainly to provide
approximations of requirements for groups of birds..."
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undulatus) fed isocaloric diets of varying protein concentrations. Proc Assoc Avian Vet, 1991, pp
227-237.
Vaughn SD: Feather picking: A mystery of avian medicine. Bird Talk Aug 1997, pp 42-47.
Wallach JD, Flieg GM: Nutritional secondary hyperparathyroidism in captive psittacine birds.
JAVMA 151:880, 1967.
Wallach JD: Nutritional diseases of exotic animals. JAVMA 157: 583-599, 1970.
Wallach JD, Boever WJ: Diseases of Exotic Animals. Philadelphia, WB Saunders Co, 1983, pp 848850.
Wolf P, et al: Enzymes activities along the intestinal tract of pet birds. Abstracts First Intl Symp Pet
Bird Nutrition, Hannover, 1997, p 28.
Wyndham E: Environment and food of the budgerigar. Austr J Ecol 5:47-61, 1980.
Twenty Years of Progress in Pet Bird Nutrition
Avian Feeding Recommendations 1977-1997
Seeds
Seeds Plus Supplements
Table Foods
Manufactured Bird Diets
Early Manufactured Foods
Pellets
Formulated Diets
Evaluating an Avian Diet
The Fallacy of Balancing a Diet at Home
Nutritional Excesses
Clinical Signs of Malnutrition
Physical Examination
Fecal Gram's Stain
Pet Bird Diets
Aviculture Diets
Refining Formulated Diets
Follow Manufacturer's Directions
Formula Variations
Nonchemical Components
Sustainable Agriculture
Avian Preventive Medicine
Practical Diet Change
Results of Proper Feeding
Transformation to Preventive Avian Practice
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