Nutrition in Psittaciformes scientific background and practical application

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Nutrition in Psittaciformes: scientific background and practical application 
 
 
Bachelor thesis Veterinary Medicine, Utrecht University 
Supervisor: dr. J.T. Lumeij 
Author: Natasja Slooten 
Student number: 0148628 
Date: 17-04-2012 
 
 
Summary 
 
In the nutrition of psittacine birds, different types of feeds with different nutritional values exist. 
This review integrates information of the nutritional requirements of psittacine birds and 
nutritional values of seed mixtures and extruded pellets. The nutritional value of seed mixtures is 
extremely low compared to that of extruded pellets. It is seen that when the dehulled seeds are 
analyzed the energy and protein content related to the volume meets the energy requirement and 
protein needs of psittacine birds. Still the dehulled seeds show low contents of calcium and 
vitamins. Extruded pellets meet the nutrient requirements of psittaciformes in most ways. Human 
food can have low contents of energy, protein or minerals related to the volume. This means, 
when given next to a seed mixture or extruded pellets, it can lower the energy, protein and 
mineral content of the nutritional intake. This is, because parrots in captivity eat limited by 
volume. 
When a parrot owner gets the recommendation of a pet shop employee to buy a seed mixture, it 
explains why the parrot owner does not know enough about the nutritional requirement of their 
parrot. Fifty percent of the pet shops have the appropriate knowledge of nutritional requirement 
of psittacine birds, but the products like extruded pellets are in half of the tested pet shops absent. 
Confronted with this situation it is extremely difficult for the parrot owner to buy the right food 
based on the right knowledge. 
 
Introduction 
 
In veterinary practice owners are seen who 
don’t have any idea what the nutritional 
requirement is of their psittacine birds. They 
believe that the daily refreshment of the 
seeds these parrots are given is enough for a 
long healthy life. A psittacine bird does not 
eat each seed of the offered seed mixture, 
but eats selective. This is the most common 
reason a psittacine bird can develop 
malnutrition. Rickets, osteomalacy, 
atherosclerosis, keratinization of the tissue 
and difficulty in laying eggs are examples 
that are observed. Cases of real malnutrition 
are seen less in veterinary practices than 10 
years ago. Still there is a long way to go 
before (potentially) owners of parrots have 
adequate knowledge to feed their parrot 
appropriately. A kind of standard already 
exists for a complete nutrition for dogs and 
cats, so their owners know very well what 
their animals need. Almost all owners of 
psittacine birds want the best for their pets. 
So why don’t they know enough about the 
nutritional requirement of their psittacine 
bird? And where is the transfer of 
information blocked, so that (potentially) 
owners of parrots are not well informed 
about a complete nutrition? This is 
concerning. If they are well informed, they 
can give their psittacine birds extruded 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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pellets. These extruded pellets exist in all 
different kinds. In relation to these pellets 
this review will evaluate in more concrete 
terms the following questions. What is the 
nutritional value of seed mixtures in relation 
to that of pellets? What is the difference 
between the pellet brands and is there any 
difference between these brands that can 
result in malnutrition? 
This article will answer these questions by 
reviewing information that is available about 
this subject. Because pet shops play a central 
role in information about this subject, a 
market research to the kind of information 
they give about nutrition of psittacine birds 
is done. 
 
Digestive anatomy of psittacine birds 
 
The digestive anatomy of psittacine birds 
differs extremely from the mammalian 
digestive tract. It consists with the beak, a 
toothless mouth, tongue, pharynx, 
esophagus, crop, proventriculus, gizzard, 
intestine, rectum, cloaca and vent. 
The digestive anatomy among different 
species of birds is extremely variable. 
Species of birds with similar feed 
preferences often have similar digestive 
tracts. Species consuming nectar and fruits, 
which are easy digestible, have short and 
simple digestive tracts. Species consuming 
seeds and animal matter, which need more 
enzymes to digest, have large stomachs and 
small lower intestines. Species consuming 
plant cell walls, which are very difficult to 
digest, have large ceca for fermentation. 
This is relative to body size. (Klasing, 1998) 
In many species of birds, parrots included, 
the crop plays an important role in feeding 
the young by regurgitating the stored food. 
The stomach is divided in two parts, the 
proventriculus (the glandular part) and the 
gizzard (the muscular part). The 
proventriculus secretes enzymes, 
hydrochloric acid and pepsin, and is very 
large in many carnivores and piscivores. The 
gizzard is on the other hand very muscular 
and bigger than the proventriculus in 
granivores and herbivores. In parrots the 
gizzard is less muscular, because they dehull 
the seeds before swallowing. Because 
nectarivores and frungivores have an easy 
digestible diet, their gizzard is only a small 
diverticulum. In this small diverticulum 
occasionally consumed insects will be 
digested. The size of the gizzard may adapt 
to the consumed diet by changing the 
volume. This means that in many birds the 
gizzard size has a seasonal fluctuation, 
because the diet changes during seasons. 
The small intestine is less variable, but the 
length and the type of villi changes between 
species. Herbivores and granivores have a 
long small intestine. However carnivores, 
nectarivores and frungivores have a short 
small intestine. Meat or fruit is quickly 
digested compared to digestion of seeds or 
plant cell walls. (Duke, 1997) 
Many birds have ceca and different types of 
ceca are known, but ceca are absent in 
psittacine birds. This means that psittacine 
birds lack the function of ceca. This function 
is microbial fermentation, extra water 
absorption, nitrogen excretion and may 
serve as a secondary lymphoid tissue. 
 
Nutritional requirement of wild psittacine 
birds 
 
Wild birds in general have evolved in a 
specific habitat in which their nutritional 
requirement is fulfilled. Birds in captivity 
eat what is given by the owner. This may 
explain obesitas in psittacine birds in 
captivity. (Ritchie et al., 1994) Also a low 
energy or nutrient intake can be explained 
when a psittacine bird eat an amount of food 
which contain too low energy or nutrients. 
The natural diet of wild psittacine birds 
consists of a wide variety of ingredients 
which include indeed seeds and nuts, but 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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3 
 
also other parts of plants, such as flowers, 
buds, leaves, fruit and bark, insects and 
larvae and meat of carcasses. (Ullrey et al., 
1991) 
 
The nutritional requirement of psittacine 
birds can be derived from the nutritional 
requirements of poultry and game birds, 
from food habits of wild birds and from 
information on trial and error feeding. (Nott 
et al., 1994; Donoghue et al., 1997; Koutsos 
et al., 2001) Food habits of wild birds are 
not well known, so this article will discuss 
the nutritional requirement of psittacinebirds by analogy of poultry and from 
information on trial and error feeding. 
 
Nutritional requirement of companion 
psittacine birds 
 
Different methods are used to approach the 
requirement of a specific nutrient in a bird. 
The easiest one is to examine the nutrient’s 
influence on growth. 
In experiments birds are fed with a specific 
diet with a certain quantity of a nutrient. At 
the point that there is no further increase in 
growth, this would be considered to be the 
growth requirement of that specific nutrient. 
This is now the suggested highest level of 
this nutrient. Studies about specific nutrient 
requirements for pet birds are rare, because 
the determination of nutrient requirement is 
extremely difficult. That is why nutrient 
recommendations, after extrapolation from 
poultry species, are used for companion pet 
birds. (Brue, 1994) The recommendations 
that were made in Brue’s study are in 
percentage (%). However, to compare the 
different seed mixtures and pellets, we will 
use the nutrient needs on energy basis 
(g/MJ). 
 
The nutrient requirement for maintenance is 
the lowest level of this nutrient and is 
needed to maintain metabolic functions and 
body temperature. All nutrient levels are 
minimized, because the primary need is for 
replacement and lost. Of course growth, 
breeding, sickness, stress and moulting may 
need more nutrients than strict maintenance. 
Breeding costs more protein and calcium, so 
is needed in the diet. Also stress responses 
in the bird’s body to mobilize and produce 
glucose for the increased energy need. 
(Ritchie et al., 1994) 
 
Energy requirement 
 
The energy content of the feed is not the 
same as the metabolizable energy the parrot 
finally uses for his body’s metabolic 
processes. After losing energy sources 
through the feces, urine, gasses and urates 
the metabolizable energy (ME) remains. 
(Harper, 2000) 
Psittaciformes make energy from 
carbohydrates, fat and protein in the diet. 
Protein is the least efficient energy source, 
because the bird’s body works hard to break 
down the proteins to amino acids and to 
excrete the formed nitrogen. 
 
When veterinarians have to tube-feed a bird, 
when the bird itself does not eat or needs 
extra energy by causes as surgery, trauma 
and sepsis, they calculate the BMR (= 
requirement for complete inactivity) of the 
bird. In this equation (formed by Sedgwick 
et al.) 
 
BMR (kcal/day) = K (W kg 
0.75
) 
 
K is a theoretical constant for kcal used 
during 24 hours for various species of birds, 
mammals and reptiles. K = 78 for non-
passerine birds. (Sedgwick et al., 1990) The 
maintenance energy requirement (MER) is 
the BMR plus the energy needed for 
digestion, absorption and normal physical 
activity. The MER can be 1.3 to 7.2 times 
the BMR and depends on the energy needed 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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for activity and thermoregulation. For 
psittaciformes in captivity with normal 
activity we use a MER 1.5 times the BMR to 
calculate the daily energy requirement. 
(Ritchie et al., 1994) If we want to calculate 
the MER by this method of an African Grey 
parrot with a weight of 400 grams, this bird 
needs 58.8 kcal/day. According to Harper 
this equation underestimates the 
maintenance energy expenditure 
requirements of all the species of birds. 
(Harper, 2000) This underestimation is due 
to the fact that the energy requirement of 
maintenance is correlated to the body mass 
and the relative size of the different organs, 
because these are the tissues that use 
oxygen. (Daan et al., 1990) 
 
However, energy requirement based on 
metabolic body weight forgets another 
important factor in energy requirements. 
This is the body composition. The metabolic 
rate of fat is much lower than that of muscle 
and liver. (Scott et al., 1992) This means 
that the lean:fat ratio in the body has 
influence on the energy requirement. Free-
flying birds that are physically active have a 
high lean:fat ratio and thus a high BMR and 
MER. Captive parrots in cages, like most pet 
parrots, have a low activity and may have a 
lower lean:fat ratio. This results in a lower 
BMR and MER. 
 
The study of Harper shows that an equation 
derived for a particular body weight is more 
useful than a general equation derived for a 
wide range of body weights. This study 
derived the energy requirement for pet birds 
by studying their daily energy expenditure. 
Two suitable equations for calculating the 
energy requirements of pet birds were those 
derived over ranges of body weight. 
 
MEE (kcal/day) = 0.62 W gr 
1.1 
This is the equation for pet birds with a 
weight less than 100 gram. MEE is the 
maintenance energy expenditure and is 
derived of the ME (metabolizable energy) 
by adding 25%. This 25% is the additional 
energy costs of uric acid formation and food 
assimilation. W is the weight in grams. 
(Harper et al., 1998) 
 
MEE (kcal/day) = 4.55 W gr 
0.55
 
This is the equation for pet birds between 
100 and 1500 grams. (Harper et al., 2000) If 
we use this equation to calculate the energy 
requirement for the example of the African 
Grey parrot with a weight of 400 grams this 
bird needs 123 kcal/day. This is almost three 
times more metabolizable energy 
requirement than in the equation of 
Sedgwick et al. 
 
Calcium needs 
 
Calcium is an essential mineral needed for 
the skeleton, but it also plays an important 
role in the body fluids to activate enzyme 
systems and maintains excitability of the 
muscles and heart. Calcium is absorbed in 
the small intestine with the help of a 
calcium-binding protein. Decrease of 
calcium absorption occurs when compounds 
as phosphates, oxalates and phytate form 
complexes with the calcium. The same 
happens when high amount of free fatty 
acids are present in the intestines. (Ritchie et 
al., 1994) 
Avian calcium metabolism is mainly 
characterized by the ability to lay large eggs 
with a calcified eggshell. A female bird 
increases the intestinal absorption and 
resorption of calcium of the medullary bone 
to require the calcium for eggshell 
calcification. (Klasing, 1998) 
A shortage of calcium is the most observed 
mineral deficiency in birds. Rickets, 
osteomalacy and difficulty in laying eggs are 
observed. An extremely high calcium intake 
may lead to toxicity. This is why a maximal 
level of calcium intake exists. Also the ratio 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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of calcium to phosphorus is important, 
because the availability of calcium for intake 
can decrease when the ratio is less than 1. 
(de Matos, 2008) 
Different researches suggest different 
optimum calcium levels. For instance Mc 
Donald suggests optimum calcium levels 
between 0.3 % and 0.7 %. (Mc Donald, 
2006) This means a minimum of 0.24 g/MJ 
and a maximum of 0.56 g/MJ. On the other 
hand the study of Schoemaker recommends 
optimum calcium levels between 0.2 g/MJ 
and 1.0 g/MJ. (Randall, 1981) 
 
Vitamin needs 
 
Vitamin A needs 
Vitamin A is needed for vision, but more 
important in birds is its effect on the 
epithelial tissues, its growth and 
differentiation. A shortage of vitamin A in 
birds results in keratinization of mucous 
membranes, poor conditions and increased 
susceptibility to infection. Plants do not 
contain active vitamin A, but containprecursors of vitamin A. These are 
carotenoid plant pigment, with the carotenes 
being the most important. Intoxication does 
not occur so quickly, unless an excess of 
1000 times of the requirement is given. A 
minimum need of vitamin A is 645 IE/MJ. 
(Schoemaker et al., 1999) The levels are 
adapted from the Exotic Bird Nutrition 
Expert Panel Report, Nutrition and 
Management Committee of the Association 
of Avian Veterinarians in 1996. 
 
Vitamin D3 needs 
No research is done to find optimum and 
toxic levels of Vitamin D3 in the diet for pet 
psittacine birds. Schoemaker recommends 
optimum levels of Vitamin D3 with a 
minimum of 40 IE/MJ and a maximum of 
161 IE/MJ. (Schoemaker et al., 1999) 
 
 
Protein needs 
 
In a study with growing cockatiels, these 
birds were fed with different percentages of 
crude protein in the diet. Those fed a 20% 
crude protein diet, reached the weaning 
stage earliest. Those fed a 10% or 15% 
crude protein diet grew slower. Those fed a 
higher than 20% crude protein diet 
developed behavior problems (like meal 
refusal) and growth depression. (Grau et al., 
1985) These are results from growing 
parrots and of course the level of crude 
protein needed by growing parrot is higher 
than needed by an adult parrot for 
maintenance. 
Westfahl quantifies the inevitable N losses 
via excrements. Eight adult Amazons were 
fed with an N-free diet. The results showed 
a minimum protein need of 1.9 g/kg 
BW
0.75
/day and this means 4-5 % required 
protein content. N losses via feathers and 
skin cells are excluded in this value. 
Including the N losses via feathers and skin 
cells, when compared with results in 
budgerigars of other publications, this leads 
to approximately 6-7% required protein 
content. This means a protein requirement of 
4.83-5.64 g/MJ protein. (Westfahl et al., 
2008) The outcome of this study is less than 
needed by budgerigars (9-10%, 7.25-8.06 
g/MJ) (Drepper et al., 1988) and cockatiels 
(11%, 8.87 g/MJ) (Koutsos et al., 2001). 
This is a much lower percentage than 
Schoemaker proposes. He proposes a 
minimum of 12 % (9.7 g/MJ) of crude 
protein intake as an optimum diet. 
(Roudybush et al., 1991) 
 
Fat needs 
 
Fat is an important energy source and is the 
primary storage form of energy in the body. 
Fat itself is not required, but the bird’s body 
cannot make certain fatty acids itself. These 
are so called essential fatty acids and must 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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be present in the diet. The primary essential 
fatty acid is linoleic acid. The uptake of 
linoleic acid has probable a negative 
influence on the existence of atherosclerosis. 
(Bavelaar et al., 2003) Based on the 
requirements of most other species, the 
linoleic acid requirement for parrots can be 
safely derived as more than 0.8 g/MJ. 
(Ritchie et al., 1994) 
 
Carbohydrate needs 
 
Carbohydrates, like glucose, are the most 
important energy source, because this is the 
only energy source the brain can use. Energy 
is derived from monosaccharides, 
disaccharides and starches. The fiber 
fraction of the diet is also formed by 
carbohydrates, but these are undigestible 
carbohydrates. The cellulose in this fiber 
fraction cannot be digested because of the 
lack of the enzyme cellulase in birds. This is 
why the carbohydrate requirement of 
psittaciformes is not examined, because at 
the same time glucose is used by all cells in 
the body and fibers are useless. (Ritchie et 
al., 1994) 
 
Nutritional value of seed mixtures and 
extruded pellets 
 
The nutrient analysis of commercial seed 
mixtures differs from the nutritional intake, 
because parrots dehull most seeds. Besides 
most seed mixtures lack information 
concerning their nutrient analysis, because 
in most European countries it is not obliged 
to supply the analysis. (Werquin 2005) A 
study of Werquin compared the nutrient 
composition of the total seed mixtures with 
that of the kernels. The nutrient composition 
of the kernels was compared with the 
commercial pellets. A big difference is the 
higher mean fat and energy content in 
kernels compared with the total seed 
mixtures. Fat and energy contents of the 
commercial pellets were extremely lower 
compared with the kernels. Werquin 
assumed that the fat (8.6 4.1 %) and 
energy (15.6 14 MJ ME/kg) content of 
the commercial pellets might be too low for 
optimal feeding. (Werquin et al., 2005) 
 
The pellets for parrots which are reviewed in 
this article are produced under low heat 
extrusion and differ from the real term 
pellets. Pelleting uses steam, pressure and a 
binding agent to bind the grains into a firm 
pellet. Extrusion has the same steps involved 
with baking, which is mixing, kneading, 
proofing, shaping, rising and cutting. The 
carbohydrates expand when heated, in 
addition to the heat effects, and put under 
pressure and the pressure released. It is 
comparable with popcorn, where the grain is 
exploded into a white fluffy ball that 
maintains its shape and fluffiness upon 
cooling. (Hand et al., 2000) 
 
The protein contents in commercial pellets 
were all higher than 7.5 g/MJ ME and thus 
seemed to be appropriate (Kamphues et al., 
1997). Bavelaar did a nutrient analysis of 
commercial seed mixtures and pellets. These 
analyzed seeds were not dehulled. Bavelaar 
found that commercial pellets have a higher 
protein content than seed mixtures, which 
were not dehulled. Three of the seven brands 
of pellets; Bingo (NASCK Veterinary 
Products Inc), Adult Life Time (Harrison’s 
Bird Diets) and Happy brok (Fitas Trading 
B.V.) have a low protein content. Even one 
pellet brand (Avi-products Parrot Bix) has a 
calcium content too high, this could lead to 
toxicity. The recommended pellet brands 
which meet the nutritional requirement of 
parrots in most ways are Exact Rainbow 
(Kaytee Prosucts Inc), High Potency 
(Harrison’s Bird Diet) and Nutribird P15 
(Versele-Laga). Nutribird P15 (Versele-
Laga) has also the highest content of linoleic 
acid. (Bavelaar et al., 2003) 
N. Slooten 
NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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7 
 
 
All seed mixtures in the study of Werquin 
had a very low calcium content. There was 
no difference between the seed mixtures and 
their dehulled fractions. On the other hand, 
the phosphorus levels in the dehulled seed 
mixtures were significantly higher than in 
the seed mixtures. This has a negative 
influence on the calcium/phosphorus 
balance. The commercial pellets had higher 
calcium levels and better 
calcium/phosphorus balance. The sodium 
content of the seed mixtures were too low, 
but appropriate in commercial pellets. This 
research shows that the analysis of the not 
dehulled seed mixture underestimates the 
energy content of their ingested portions 
with 36%. The nutrient analysis of the 
dehulled fraction of the seed mixture gives 
us an idea of the real parrot diet. Birdfood 
producers should be encouraged to provide 
these data. 
The specific feeding behavior of parrots, 
being selective eaters and 
dehulling/dehusking of seeds, changes the 
nutritional intake compared with the 
nutritional value of seeds diets. Seed kernels 
contain a higher amount of phosphorus but a 
lower amount of calcium in relation to 
whole seeds. This worsens the already 
suboptimal Ca:P ratio. (Werquin et al., 
2005)Eating of excess fruit and vegetables lowers 
the energy density of a diet (Donoghue et 
al., 1997). A feeding trial done by Kalmar 
on six yellow-shouldered amazons assessed 
the nutritional impact of parrot-specific 
feeding behavior and the influence of 
additional provision of fruit next to the seed 
mixture. Provision of fruit in combination 
with seed diet lowered voluntary energy 
intake, without an adequate protein intake. 
This can be applied in case of obesity. 
(Kalmar et al., 2010) 
 
In the study of Hess 135 pet birds were 
examined to determine their weekly food 
consumption. Two independent laboratories 
analyzed the formulated products and seeds 
for their nutrient content. The outcome of 
this study showed that pet birds consuming 
less than 50 % of their diet from pellets had 
insufficient intakes of vitamin A and D3 and 
calcium. Diets with a high percentage of 
human food were low in protein, energy, 
vitamins and minerals. Diets with a high 
percentage of seeds were high in fat and 
deficient in vitamin A and D3 and calcium. 
(Hess et al., 2002) 
 
Table 1: Summary of nutrient analysis for different types of food for psittaciformes 
 
Nutrient analysis 
 
Seed mixtures Dehulled 
seed/kernels 
Extruded pellets Human food 
Energy Low High High Low 
Calcium Low Low High High 
Vitamin A Low Low High Low 
Vitamin D3 Low Low High Low 
Protein Low High High Low 
Linoleic acid High High High High 
 
 
Information to the public 
 
No obligatory education requirements exist 
for employees who work in a pet shop. In 
the future the DIBEVO (Dutch organization 
of pet shop retailers) wants to introduce a 
kind of professional degree for employees of 
a pet shop. Right now anyone can open a pet 
N. Slooten 
NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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8 
 
shop and work there. There is no specific 
knowledge needed to sell bird food or even 
sell a bird. (Source: DIBEVO) 
 
Most seed mixtures lack information 
concerning their nutrient analysis, because 
in the Netherlands it is not obliged to supply 
the analysis. This nutrient analysis on the 
packing of animal food is only obliged by 
law for dogs, cats and fur-bearing animals. 
When there is a nutrient analysis on the 
packing of food for psittaciformes the VWA 
(Dutch Food Authority) can ask for an 
explanation. The only thing what is obliged 
by law is that on the packing of the animal 
food there has to be an instruction how to 
use it by the owner. This means how much 
of the food is needed per day and that it has 
to be supplied in combination with water. A 
warning for selective eating of these 
psittaciformes is not obliged. In this way a 
random person with no knowledge of parrots 
can develop a seed mixture for parrots and 
sell it on the market. The only thing what 
this person has to do is to register as a food 
company for animals. (source: produktschap 
Diervoeding) This may be a reason why so 
many pet shop owners and breeders 
recommend their own brand of seed 
mixtures as the best for a parrot. 
 
LICG is a dutch institute that claims to give 
objective and independent information about 
buying and taking care of pets responsibly. 
Their main ambition is to improve the health 
of pets. The information they give about 
buying and taking care of pet birds is 
extremely wide, which may be too 
overwhelming for (potentially) parrot 
owners. For seventeen different species of 
birds they developed a so called leaflet with 
information about the pet bird’s natural 
habitat, accommodation, nursing, nutritional 
requirement, reproduction, diseases and 
acquisition costs. They did not focus on the 
main problem in veterinary medicine of 
birds, which is malnutrition. They advice to 
feed a psittacine bird a mixture of extruded 
pellets, fruits, vegetables and a little amount 
of seeds as nuts to give as rewards. This 
advice leads a lot of room for the owner to 
create their own ideal meal for their pet bird, 
which leads most of the time to a pet bird 
which eats more or only seeds instead of the 
other offered extruded pellets, fruits and 
vegetables. 
In the same advice of the LICG owners are 
recommended to buy their extruded pellets 
in pet shops and veterinary clinics. In the 
little market research which is done, half of 
those shops do not have any extruded pellets 
in assortment. This makes it extremely hard 
for the parrot owner to get the right food for 
their pet bird. (source: LICG) 
 
In the explorative market research it is 
concluded that the knowledge of pet shop 
employees differs extremely. In this little 
research ten different pet shop employees in 
Amsterdam en Utrecht were asked for the 
best nutrition to feed a parrot. Fifty percent 
of the investigated pet shop employees tell 
about the existence of pellets when asked 
about the best feeding for parrots. The 
remarkable fact is that these same shops do 
not sell these recommended pellets, but only 
the seed mixtures. Other pet shop employees 
recommend their own brand of seed 
mixtures, while in those cases the extruded 
pellets were available in the shop. Only one 
pet shop could tell exactly the benefits of the 
extruded pellets, but also how difficult it is 
to change the feed behavior when a parrot is 
used to eat seeds. With a lot of information 
about slowly changing the diet this pet shop 
was a favorable exception. It is possible that 
pet shops are afraid of unhappy customers 
when selling the extruded pellets, because of 
these difficulties in changing feed behavior. 
 
 
 
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NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND 
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9 
 
Conclusion 
 
The nutritional value of seed mixtures is 
extremely low compared to that of extruded 
pellets. It is seen that when the dehulled 
seeds are analyzed the energy and protein 
content meets the energy requirement and 
protein needs of psittaciformes. Still the 
dehulled seeds show low contents of 
calcium and vitamins. Extruded pellets meet 
the nutrient requirements of psittaciformes 
in most ways. Human food can have low 
contents of energy, protein or minerals 
related to the volume. This means, when 
given next to a seed diet or pellet diet, it can 
lower the energy, protein and mineral 
content of the nutritional intake. This is, 
because parrots in captivity eat limited by 
volume. 
When a parrot owner gets the 
recommendation of a pet shop employee to 
buy a seed mixture, it explains why the 
parrot owner does not know enough about 
the nutritional requirement of their parrot. 
Fifty percent of the pet shops have the 
appropriate knowledge of nutritional 
requirement of psittacine birds, but the 
products like extruded pellets are in half of 
the tested pet shops absent. Confronted with 
this situation it is extremely difficult for the 
parrot owner to buy the right food based on 
the right knowledge. 
 
Discussion 
 
In many studies the authors assume that 
psittaciformes eat to meet their energy 
requirements and can control their energy 
intake very carefully. They base this on a 
study from 1954, a study of the energy 
requirement of chickens. (Hill et al., 1954) 
They automatically make a comparison to 
parrots. But parrots in captivity are not the same 
as parrots in the wild. 
 
Bavelaar et al. came to the conclusion that three 
of the seven analyzed pellets had a too low 
protein content. They used a protein need forparrots which has to be more than 9.7 g/MJ. This 
recommended protein need is adapted from the 
protein need of poultry. Westfahl however, after 
a research to the protein needs of amazons, 
concluded to a much lower need of protein, 
namely 4.83-5.64 g/MJ. Considering that the 
study of Westfahl is much more accurate we can 
conclude that the protein content of all the 
pellets is sufficient. 
 
This shows very clearly that more research 
is needed among psittaciformes to determine 
the nutrient needs in a more exact way. 
Research results from the field of poultry 
should be regarded with reluctance. 
 
In the study of Hess human food was one 
category and this was not specified. This 
means that they did not make any difference 
between French fries with mayonnaise for 
example and a salad. The fries contain a lot 
of energy in contrary to the salad. 
 
It is very urgent that the producers of certain 
seed mixtures should be obliged to do a 
nutrient analyse and show it clearly on the 
package. This should apply not only for the 
seed mixture, but also for the dehulled 
fraction. Also a warning should be added on 
the package, that when the parrot eats 
selectively, the product (in this case the seed 
mixture) is not well used and may cause 
malnutrition. 
 
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