nutrition in psittaciformes scientific background and practical application

1

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

N. Slooten

NUTRITION IN PSITTACIFORMES: SCIENTIFIC BACKGROUND

AND PRACTICAL APPLICATION

2

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

N. Slooten



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 psittacine

birds 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

N. Slooten



4

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

N. Slooten



5

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 contain

precursors 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

BW0.75

/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

N. Slooten



6

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



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

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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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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 for

parrots 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.

References National Research Council Nutrient

Requirements of Poultry. 8th rev ed.

Washington, DC: National Academy Press;

1982.

Bavelaar F.J., Beynen A.C. (2003).

Beoordeling van commerciele

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