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Insights on Psittacine Nutrition Through the Study of Free-Living Chicks

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  • Auckland Zoo

Abstract and Figures

The Psittacidae is one of the most endangered families of birds in the world. Knowledge of its nutrition is important for understanding their survival and productivity in the wild, as well as for their adequate husbandry in captivity. Hand-rearing is a common practice for this group. However, research on their requirements is limited. Analysis of the crop content of chicks can provide new insights into psittacine nutrition, but it is limited by the small sizes of samples which can be obtained. We sampled the crops from free-living chicks of scarlet macaws and red-and-green macaws from southeastern Peru, Cuban parrots from the Bahamas, lilac-crowned parrots from northwestern Mexico, and thick-billed parrots from northern Mexico. The predicted metabolizable energy, protein, fat, minerals, profile of essential amino acids and profile of fatty acids of the crop samples, as well as from 15 commercial hand-rearing formulas, were analyzed and contrasted. Near Infrared Spectroscopy was shown to be a valid technique for the nondestructive, low cost prediction of a variety of nutritional attributes of crop samples as small as 0.5 g dry weight, expanding the possibilities of wild animal nutrition research. The diets of the five studied species presented remarkable similarities and common patterns. The predicted dietary metabolizable energy and fat concentrations were particularly similar among species, the thick-billed parrot being the one with the most unique nutrient profile. The fatty acid profile of the crop contents differed markedly among genera, with the thick-billed parrot closer to the macaws than to the parrots. In comparison with the crop samples, the hand feeding formulas presented lower fat, Mg, arginine, and valine concentrations. The wide variation in nutrients suggests that there is not yet a consensus among manufacturers concerning the correct nutrition for growing psittacines. It is suggested that a single formulation could be used to hand-rear macaws and parrots from half its nesting time to fledging, and further research should focus on their nutrition during the first half. Our results suggest that manufacturers should evaluate if increasing the concentrations of crude fat, Mg, arginine, and valine in commercial formulas enhances psittacine chick growth and health.
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INSIGHTS ON PSITTACINE NUTRITION THROUGH THE STUDY OF
FREE-LIVING CHICKS
A Dissertation
by
JUAN CORNEJO
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
May 2012
Major Subject: Veterinary Microbiology
Insights on Psittacine Nutrition through the Study of
Free-living Chicks
Copyright 2012 Juan Cornejo
INSIGHTS ON PSITTACINE NUTRITION THROUGH THE STUDY OF
FREE-LIVING CHICKS
A Dissertation
by
JUAN CORNEJO
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
Approved by:
Co-Chairs of Committee, Donald J. Brightsmith
Christopher A. Bailey
Committee Members, Ian R. Tizard
Ellen S. Dierenfeld
Head of Department, Linda Logan
May 2012
Major Subject: Veterinary Microbiology
iii
ABSTRACT
Insights on Psittacine Nutrition through the Study of Free-living Chicks.
(May 2012)
Juan Cornejo, B.S., Universidad de Navarra
Co-Chairs of Committee: Dr. Donald J. Brightsmith
Dr. Christopher A. Bailey
The Psittacidae is one of the most endangered families of birds in the
world. Knowledge of its nutrition is important for understanding their survival and
productivity in the wild, as well as for their adequate husbandry in captivity.
Hand-rearing is a common practice for this group. However, research on their
requirements is limited. Analysis of the crop content of chicks can provide new
insights into psittacine nutrition, but it is limited by the small sizes of samples
which can be obtained. We sampled the crops from free-living chicks of scarlet
macaws and red-and-green macaws from southeastern Peru, Cuban parrots
from the Bahamas, lilac-crowned parrots from northwestern Mexico, and thick-
billed parrots from northern Mexico. The predicted metabolizable energy,
protein, fat, minerals, profile of essential amino acids and profile of fatty acids of
the crop samples, as well as from 15 commercial hand-rearing formulas, were
analyzed and contrasted. Near Infrared Spectroscopy was shown to be a valid
technique for the nondestructive, low cost prediction of a variety of nutritional
attributes of crop samples as small as 0.5 g dry weight, expanding the
possibilities of wild animal nutrition research. The diets of the five studied
species presented remarkable similarities and common patterns. The predicted
dietary metabolizable energy and fat concentrations were particularly similar
among species, the thick-billed parrot being the one with the most unique
nutrient profile. The fatty acid profile of the crop contents differed markedly
among genera, with the thick-billed parrot closer to the macaws than to the
iv
parrots. In comparison with the crop samples, the hand feeding formulas
presented lower fat, Mg, arginine, and valine concentrations. The wide variation
in nutrients suggests that there is not yet a consensus among manufacturers
concerning the correct nutrition for growing psittacines. It is suggested that a
single formulation could be used to hand-rear macaws and parrots from half its
nesting time to fledging, and further research should focus on their nutrition
during the first half. Our results suggest that manufacturers should evaluate if
increasing the concentrations of crude fat, Mg, arginine, and valine in
commercial formulas enhances psittacine chick growth and health.
v
DEDICATION
A mi madre, por haberme enseñado a observar y apreciar la naturaleza.
A mi padre, por ser el ejemplo a seguir.
vi
ACKNOWLEDGEMENTS
I am grateful to my committee co-chairs, Dr. Brightsmith and Dr. Bailey,
and the members of my committee, Dr. Dierenfeld and Dr. Tizard for their wise
guidance and support throughout the course of this research. Thanks to the staff
of the Veterinary Pathobiology Department, particularly to P. Vychopen and D.
Turner, from all their help during my time at Texas A&M University. This
research would have not being possible without the collaboration of Dr. Renton,
G. Ortiz Maciel, and C. Stahala, or without the hard work of L. Ortiz Cam, J.
Cruz Nieto, G. Vigo Trauco, and the staff of Tambopata Research Center, my
sincere gratitude to all of them. Early discussions with R. Jordan, X. Viader and
L. Koutsos helped shaping the direction of this research. The comments of
anonymous reviewers improved the content chapters II and III. Thanks also to
Dr. Clum for letting me dedicate time during the final writing phase. My gratitude
to the Morris Animals Foundation, the AZA Parrot TAG, the Association for
Parrot Conservation, and Zupreem, for funding my research. I am indebted to F.
Camacho and to D. Richardson, as their support allowed me to go through the
grad school years. I would not have been able to accomplish this work without
the help and encouragement of my family, especially Henar and Nico. Finally,
thanks to Rocio, for her love through these last few but long years.
vii
TABLE OF CONTENTS
Page
ABSTRACT ................................................................................................. iii
DEDICATION .............................................................................................. v
ACKNOWLEDGEMENTS ............................................................................ vi
TABLE OF CONTENTS ............................................................................... vii
LIST OF FIGURES ...................................................................................... x
LIST OF TABLES ........................................................................................ xiii
CHAPTER
I INTRODUCTION ...................................................................... 1
General background ........................................................... 1
Chick diet and hand feeding ................................................ 2
Diet texture .......................................................................... 4
Nutritional requirements for growth ...................................... 4
Study species and sites ....................................................... 9
Research objectives ............................................................ 10
II PREDICTION OF THE NUTRITIONAL COMPOSITION OF
THE CROP CONTENTS OF FREE-LIVING SCARLET
MACAW CHICKS BY NEAR-INFRARED REFLECTANCE
SPECTROSCOPY .................................................................... 12
Synopsis ............................................................................. 12
Introduction .......................................................................... 13
Methods ............................................................................... 14
Results ................................................................................ 16
Discussion ........................................................................... 17
viii
III PREDICTED METABOLIZABLE ENERGY DENSITY AND
AMINO ACID PROFILE OF THE CROP CONTENTS OF
FREE-LIVING SCARLET MACAW CHICKS (Ara macao) ....... 20
Synopsis ............................................................................. 20
Introduction .......................................................................... 21
Methods ............................................................................... 22
Results ................................................................................ 26
Discussion ........................................................................... 29
IV FATTY ACID PROFILES OF CROP CONTENTS OF FREE-
LIVING PSITTACINES AND IMPLICATIONS FOR HAND-
FEEDING ... .............................................................................. 33
Synopsis ............................................................................. 33
Introduction .......................................................................... 34
Methods ............................................................................... 35
Results ................................................................................ 38
Discussion ........................................................................... 49
V NUTRITIONAL AND PHYSICAL CHARACTERISTICS OF
COMMERCIAL HAND-FEEDING FORMULAS FOR
PARROTS ................................................................................ 55
Synopsis ............................................................................. 55
Introduction .......................................................................... 56
Methods ............................................................................... 57
Results ................................................................................ 60
Discussion ........................................................................... 69
VI NUTRITION OF FREE-LIVING NEOTROPICAL PARROTS
CHICKS, AND IMPLICATIONS FOR HAND-FEEDING
FORMULAS .............................................................................. 74
Synopsis ............................................................................. 74
ix
Introduction .......................................................................... 75
Methods ............................................................................... 76
Results ................................................................................ 81
Discussion ........................................................................... 94
VII CONCLUSIONS AND RECOMMENDATIONS ......................... 98
LITERATURE CITED ................................................................................... 102
VITA ............................................................................................................ 122
x
LIST OF FIGURES
FIGURE Page
1 Near infrared reflectance spectra of crop samples from free-ranging
scarlet macaws (Ara macao) in southeastern Peru. ......................... 17
2 Fatty acid profile of crop content samples of six psittacine species,
15 commercial hand-feeding formulas, 11 different commercially
available feeding oils, the palm fruits that constitute the main foods
of the hyacinth and Lear’s macaws, and the average of three
poultry feeds. .................................................................................... 44
3 Percentage of solids in suspension of 15 commercial parrot hand-
feeding formulas prepared according to the manufacturer’s
directions for 1 wk old bird. ............................................................... 60
4 Proximate analysis of 15 commercial parrot hand-feeding formulas,
compared with the average concentrations found in the crop
content of free-living scarlet macaw (Ara macao) chicks from
southeastern Peru ............................................................................. 62
5 Mineral concentrations of 15 commercial parrot hand-feeding
formulas compared with the average concentrations found in the
crop content of free-living scarlet macaw (Ara macao) chicks from
southeastern Peru, and the nutritional requirements for growing
leghorn chickens. .............................................................................. 65
xi
6 Mineral concentrations of 15 commercial parrot hand-feeding
formulas compared with the average concentrations found in the
crop content of free-living scarlet macaw (Ara macao) chicks from
southeastern Peru, and the nutritional requirements for growing
leghorn chickens.. ............................................................................. 66
7 Comparison of the essential amino acids profile of 15 commercial
parrot hand-feeding formulas, the crop content of free-living scarlet
macaw (Ara macao) chicks from southeastern Peru, and the
nutritional requirements for growing leghorn chickens ...................... 68
8 Predicted metabolizable energy in the crop samples from free-living
chicks of five different parrot species and commercial parrot hand-
feeding formulas... ............................................................................ 83
9 Crude protein in the crop samples from free-living chicks of five
different parrot species, commercial parrot hand-feeding formulas,
and the requirements of 6-12 wk leghorn chickens... ........................ 84
10 Crude fat in the crop samples from free-living chicks of five different
parrot species and commercial parrot hand-feeding formulas... ....... 85
11 Relative proportions of crude protein, fat and carbohydrates + ash
per unit of metabolic energy, in the crop samples from free-living
chicks of five different parrot species, and 15 commercial parrot
hand-feeding formulas.... .................................................................. 87
xii
12 Calcium concentration in the crop samples from free-living chick of
five different parrot species, commercial parrot hand-feeding
formulas, and the requirements of 6-12 wk leghorn chickens.. ......... 90
13 Calcium:Phosphorus ratio in the crop samples from free-living
chicks of five different parrot species, commercial parrot hand-
feeding formulas, and the requirements of 6-12 wk leghorn
chickens.. .......................................................................................... 91
14 Sodium concentration in the crop samples from free-living chicks of
five parrot species, commercial parrot hand-feeding formulas, and
the requirements of 6-12 wk leghorn chickens.... .............................. 92
xiii
LIST OF TABLES
TABLE Page
1 Nutritional values and calibration equation performance for crop
samples from free ranging scarlet macaw (Ara macao) chicks
collected in southeastern Peru .......................................................... 18
2 Crude protein and amino acid composition in g/MJ PME of crop
contents of free-living scarlet macaw chicks (Ara macao), crop
contents of kakapo (Strigops habroptila) chicks, and the nutritional
requirements of budgerigars (Melopsittacus undulatus), lovebirds
(Agapornis spp.), and leghorn chickens (Gallus gallus). ................... 27
3 Parrot crop samples used for this study. Scarlet macaw (Ara
macao), red-and-green macaw (Ara chloropterus), Cuban parrot
(Amazona leucocephala bahamensis), lilac-crowned parrot
(Amazona finschi), thick-billed parrot (Rhynchopsitta
pachyrhyncha), kakapo (Strigops habroptila). ................................... 37
4 Total fatty acid and crude fat content in crop contents from the five
studied free-living psittacine species, the kakapo, 15 commercial
hand-feeding formulas, and the preferred food of the free-ranging
hyacinth macaw. Values in % of dry matter and in g/MJ
metabolizable energy... ..................................................................... 39
5 Fatty acid profile, according to chain length, in crop contents from
the five studied free-living psittacine species, the kakapo, 15
xiv
commercial hand-feeding formulas, and the preferred food of the
free-ranging hyacinth macaw.... ........................................................ 42
6 Fatty acid profiles by degree of saturation of crop content samples
from five free-living psittacine species, the kakapo, and the average
of 15 commercial hand-feeding formulas.... ...................................... 43
7 Saturated fatty acid composition of crop content samples from the
five studied free-living psittacine species, the kakapo, the average
of 15 commercial hand-feeding formulas, and the preferred food of
the free-ranging hyacinth macaw.... .................................................. 45
8 Monounsaturated fatty acid composition of crop content samples
from the five studied free-living psittacine species, the kakapo, and
the average of 15 commercial hand-feeding formulas.... .................. 47
9 Polyunsaturated fatty acid composition of crop content samples
from the five studied free-living psittacine species, the kakapo, and
the average of 15 commercial hand-feeding formulas.... .................. 50
10 n6 and n3 families of polyunsaturated fatty acids and their ratio in
the crop content from the five studied free-living psittacine species,
the kakapo, and the average of 15 commercial hand-feeding
formulas... ......................................................................................... 52
11 Nutritional values and calibration equation performance for crop
samples from free ranging scarlet macaw (Ara macao) chicks
collected in southeastern Peru .......................................................... 58
xv
12 Macronutrients and mineral analysis of 15 commercial parrot hand-
feeding formulas and the crop of free-living scarlet macaw (Ara
macao) chicks from southeastern Peru, compared with the
nutritional requirements of growing leghorn chickens... .................... 63
13 Comparison of the true protein and essential amino acids profile in
ME basis of 15 commercial parrot hand-feeding formulas, the crop
content of 20 free-living scarlet macaw (Ara macao) chicks from
southeastern Peru, and the nutritional requirements of growing
leghorn chickens.. ............................................................................. 67
14 Average concentration of nutrients in the hand-feeding formula (wet
basis) to be offered to scarlet macaw (Ara macao) chicks at one (86
g) and six weeks (837 g) of age, when following the manufacture’s
preparation suggestions.. .................................................................. 69
15 Characteristics of the parrot crop samples include in this study.
Scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus), Cuban parrot (Amazona leucocephala bahamensis),
lilac-crowned parrot (Amazona finschi), thick-billed parrot
(Rhynchopsitta pachyrhyncha). ......................................................... 77
16 Predicted metabolizable energy and proximate analysis of crop
contents from the five studied free-living psittacine species
compared with the analysis of 15 commercial hand-feeding
formulas, and the nutritional requirements of 6-12 wk leghorn
chicken (11.9 MJ/kg).. ....................................................................... 82
xvi
17 Macro and micro mineral analysis of crop contents from the five
studied free-living psittacine species, from 15 commercial hand-
feeding formulas, and the requirements of 6-12 wk leghorn
chickens (11.9 MJ/kg). ...................................................................... 88
18 Essential amino acid concentration, as % of true protein, of the crop
samples from free-living chick of five different parrot species
(scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus), Cuban parrot (Amazona leucocephala bahamensis),
lilac-crowned parrot (Amazona finschi), thick-billed parrot
(Rhynchopsitta pachyrhyncha), and comparison with the range
found in commercial parrot hand-feeding formulas .......................... 93
19 Sampled chick characteristics, predicted metabolizable energy
needs, food energy density, and calculated daily food intake from
scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus), Cuban parrot (Amazona leucocephala bahamensis),
lilac-crowned parrot (Amazona finschi), thick-billed parrot
(Rhynchopsitta pachyrhyncha) .......................................................... 95
1
CHAPTER I
INTRODUCTION
General background
Macaws and other members of the Psittacidae family have been bred in
captivity for more than 3000 years (1). In part due to their popularity as pets,
they have become the most endangered order of birds in the world (over 25% of
the species are listed as threatened and an additional 11% as near-threatened
(2). Knowledge of nutrition is important for the adequate husbandry of the birds
kept as pets, and for the efficient propagation of individuals kept in zoological
collections for their ex situ conservation (3-6). It is also needed for
understanding survival and productivity (6, 7), and it is therefore critical to
implement adequate conservation strategies (3, 8, 9). There is an increasing
volume of research on the nutritional requirements for growth and maintenance
of psittacines (4, 10-22), but malnutrition is still one of the main issues in the
care and propagation of this group (4, 5, 23-25) and providing nutritionally
adequate diets must be a primary concern
Most psittacines consume plant-based diets and are classified as
herbivores (26). Studies of the diet of free ranging Neotropical psittacines are
scarce (9, 27-34). While it is possible to identify the main food sources of adult
parrots through field observations (9, 35), field conditions usually make it very
difficult to determine the less common items in the diet (36). In addition, parrot’s
extensive food manipulation and processing makes it challenging to quantify the
exact proportion of each food type consumed (8, 15, 34). As a result it is not
possible to determine nutritional content of wild adult diets.
___________
This dissertation follows the style of The Journal of Nutrition.
2
Parrots feed their chicks an undigested regurgitate which the chicks hold
in their crop before passing to the stomach for digestion. Analysis of these chick
crop contents provides the opportunity to determine the composition of the chick
diets as fed, unaffected by differential digestion (36-39). A variety of techniques
exist to collect samples directly from the crops and stomachs of individual birds
(36, 37). Unfortunately, the small size of the individual samples greatly limits the
traditional wet lab analyses which can be done. Pooling samples of similar
characteristics is often necessary to achieve the minimum sample sizes needed
for analysis but this reduces statistical power needed to address ecological
hypotheses (40, 41). Through crop sampling is also possible to directly
determine each food type (32, 34, 35, 40) and the nutritional composition of the
diet as a whole (40, 41).
To date there are very few studies that have looked at the nutritional
composition of free ranging parrot chicks diet (9, 40, 41). Research into the
nutrition of parent-fed chicks has been published for only two species, the
scarlet macaw (Ara macao) from southeastern Peru (40, 42), and the kakapo
(Strigops habroptila) from New Zealand (41). Given the diversity of food habits
and ecology among parrot species it is impossible to generalize from these
scant observations to the nutritional requirements of the family.
The overall goal of this dissertation is to use information from five species
of free ranging (wild) psittacine chicks to provide novel information on psittacine
nutrition which can be used to improve the hand-rearing of psittacines.
Chick diet and hand feeding
Hand rearing is a common practice for the propagation of psittacines,
both for the pet market (43-45) and for conservation aviculture (46-50). Accurate
information on the nutritional requirements of growing animals is essential for the
formulation of captive rearing diets (51). However, research on the nutrition of
growing psittacines is limited and the nutritional requirements for the growth of
3
psittacine chicks are not well understood (12, 22, 52-56). As a result, nutritional
imbalances resulting in problems such as stunted development, rickets, and
vitamin deficiencies (5, 13, 57, 58) have been common, and still occur for some
species (4). Generally hand fed parrots grow slower than parent fed (56, 59, 60),
and present a delayed fractional grow rate (% increase in body weight per day)
(3, 61). In the absence of further research, or comprehensive data on the
nutrient composition of the diets of wild psittacines, nutritional prescriptions for
their maintenance and growth are generally extrapolated from dietary
recommendations for poultry (62) and modified based on experience rather than
on scientific study (4). However, psittacines are not closely related to poultry
which have been artificially selected for multiple generations and differ both
developmentally (63) and ecologically (64). Therefore, it is questionable if the
available poultry data adequately model the dietary requirements of psittacine
chicks.
Hand feeding diets for psittacines were traditionally home-made recipes
which required extensive preparation (3, 44, 45, 55, 58, 65) but now there is a
wide array of commercially available products that require minimal preparation
(4, 48). These products are intended to be used without supplementation and
fulfill the nutritional requirements of most species. In a nutritional analysis of 11
commercial hand feeding products Wolf and Kamphues (56) found great
differences in the nutritional content, with an average ME concentration of 15.2
MJ/kg DM (13.0-16.8), crude protein 14.4 g/MJ ME and crude fat 7.38 g/MJ ME.
When compared with the nutritional requirements of budgerigars (Melopsittacus
undulatus) and lovebirds (Agapornis sp.)(52), they found a number of formulas
with insufficient concentrations of the sulphur amino acids methionine and
cystine and others with apparently excessive calcium concentrations.
4
Diet texture
Parrots feed their chicks a regurgitated coarse mix of foods. Preliminary
data from 31 crop contents of scarlet macaws (Ara macao) chicks in Peru (40),
age 28-60 days, found that the largest food particles averaged 9.0 x 4.5 mm,
and there was little variation with chick age. Feeding whole grain to young
chickens has been associated with a more muscular gizzard and less
occurrence of proventricular hypertrophy (66, 67). Greater development of the
gastrointestinal tract suggests that feed may be retained in the upper digestive
tract for a longer period allowing for increased enzymatic digestion and digestive
efficiency (66, 68, 69). Captive psittacines are usually hand fed diets of very
small particle size (finely ground). When attempting to hand feed a coarse
texture similar to the regurgitate fed by their parents (40), the mortality of newly
hatched chicks increased and created problems with the food passage time in
older chicks (58). The capacity of a formula to maintain the solids in suspension
is another important factor because separation of ingredients at the mixing dish
will result in nutritional inconsistencies of the formula. If this situation occurs in
the chick’s crop, the solids will settle while the liquid is absorbed, making it more
difficult to pass, and leading to dehydration and crop stasis.
Nutritional requirements for growth
Nutrients in the diet supply energy to fuel metabolism and the precursors
for the synthesis of structural and functional macromolecules. The quantitative
and qualitative aspects of nutrient requirements are well understood for
commercial poultry species (62), but information about the requirements for wild
avian species is very limited (6, 26).
Energy
The metabolizable energy (ME) is the amount of food energy that
becomes available to the bird when nutrients such as amino acids,
5
carbohydrates and lipids, are oxidized during metabolism. Knowledge of energy
requirements is very important because birds usually eat the quantity of food
needed to satisfy their energy needs (4, 26). The amount of food required
depends upon the density of metabolizable energy in the diet and its digestibility
(26). Thus, when provided low energy density diets (e.g., high-fiber), animals
increase the amount consumed but decrease total intake when given high
energy diets (e.g., high-fat). Growing birds need energy for basal requirements,
thermoregulation, physical activity, and growth. Kamphues and Wolf (70)
measured the rate of protein and lipid gain in growing budgerigars (177 mg/d
and 160 mg/d, respectively) and lovebirds (153 mg/d and 153 mg/d,
respectively). Correcting these rates for the cost of deposition (52 kJ/g) gives the
additional energy needed for growth at 17.5 kJ/g for budgerigars and 15.9 kJ/g
for lovebirds. The relative amount of energy needed for growth is based upon
the fractional growth rate (26). In altricial nestlings, the proportion of energy
requirement partitioned to growth changes with age, being proportionally highest
at the beginning when percent weight gain is the highest and thermoregulation
and activity are minimal (26). Earle and Clarke (15) reported that the peak
energy provisioned to parent fed budgerigar chicks was maximal about a week
before fledging at 28 kJ/chick/day. Birds in the order Psittaciformes are among
the slowest growing of altricial species but they also develop endothermy at an
early age (71, 72). Thus, their energy requirements are likely to be more similar
to precocial species than to highly altricial species like Passeriformes, which
grow faster and thermoregulate later. The data suggest that this is the case, as
the content of crops of free ranging kakapo (Strigops habroptila) chicks
contained 7.7 MJ ME/kg (41), although optimal growth of chickens 0 to 12 weeks
of age is achieved when offering a diet with 11.9 MJ ME/kg (62). However,
according to Wolf and Kamphues (56) the energy density of hand rearing
formulas for parrots varies widely (13.0-16.8 MJ ME/kg) and consistently
exceeds estimated needs.
6
Protein and amino acids
Proteins are the primary constituents of animal tissues and are also
important as enzymes, hormones, and membrane components (6). While crude
protein is commonly reported in nutritional studies, its interpretation without
considering the amino acid (AA) profile can be misleading, as birds don’t have a
crude protein requirement per se (62). An essential level of protein must be
included in the diet to meet nitrogen requirements of the animal, but the
requirements depend on protein digestibility and the relative concentrations of
the AA.
In growing birds the main fate of the dietary protein is for tissue accretion
and, in smaller proportion, for maintenance (26). The relative requirements for
growth are highest at hatch and decrease over time, as the chicks’ fractional
growth rate slows. The suggested requirements of crude protein for 0-12 weeks
leghorn chickens in a corn-soybean meal diet (11.9 MJ ME/kg) is 16-18% DM
(62). However, because of the higher fractional growth rate of psittacine birds
(due to their altricial mode of development), an increase in the total amino acid
requirements might be expected. A study of the crop content of free ranging
kakapo chicks found 8.4% DM protein in crop samples (7.7 MJ ME/kg)(41) while
scarlet macaws chicks in Peru had 23.5% DM protein in their crop contents (40).
Traditionally the AA can be divided into essential amino acids (EAA),
whose carbon skeletons cannot be synthesized at all by the body or are
synthesized in insufficient quantities to meet cellular requirements, and non-
essential amino acids (NEAA) which can be synthesized de novo. Although all
20 protein-forming α-amino acids are physiologically essential and should be
considered when formulating diets (73-75), only 12 amino acids (arginine,
isoleucine, leucine, lysine, methionine, phenylalanine, valine, tryptophan,
threonine, glycine, histidine, and proline) are considered essential for birds (62,
74, 76, 77). Amino acid requirements have been studied extensively in
commercial fowl (62, 77, 78). However, psittacine AA requirements have
7
received limited attention, with most of the studies focused on adult maintenance
requirements (15, 17, 19, 79). The AA dietary requirements depend on the
concentrations of the EAAs relative to an animal's needs (80), and will be driven
by the concentration of the limiting EAA. The AA balance needed for growth is a
close reflection of the profile of AA incorporated into tissue protein (26). The
amino acid composition of the tissues of budgerigars is very similar to that of
chickens (81), so the balance of AA required may be similar among a broad
range of avian taxa (4). Differences in the concentration and balance of AA
among species would be driven by the different developmental patterns and
fractional growth rates (26). Experiments with captive cockatiels have shown
that optimum growth is achieved feeding a diet with 20% DM crude protein
(1.0% methionine + cysteine, 1.5% lysine, 14.6 MJ ME/kg) (53). A diet with
13.2% protein (0.65% lysine, 0.78% methionine + cysteine, 13.4 MJ ME/kg)
supported maximal growth in growing budgerigar chicks (82).
Fat and fatty acids
Dietary lipids supply energy, essential fatty acids (FA), vitamin
transportation, and pigments. Fatty acids have remarkably varied roles in animal
physiology. Fatty acids can be saturated (SFA) if all the carbons of the tail are
saturated with hydrogen atoms, or unsaturated if they contain one or more
double bonds. Depending on the number of double bonds, FA can be
monounsaturated (MUFAs), or polyunsaturated (PUFAs). Linoleic acid (C18:2
n6) and α-linolenic acid (C18:3 n3) are considered essential nutrients because
they have double bonds beyond carbon 9 and birds lack the desaturases
needed to produce them. These two FA and their derivatives are referred to as
the n-6 and n-3 families of FA. Arachidonic (C20:4 n6) and docosahexaonic acid
(C22:6 n3) cannot be synthesized by carnivorous mammals or fish from linoleic
and linolenic precursors, and it is unknown if birds have the capacity to
synthesize them. (83).
8
Linoleic acid is the only essential FA for which dietary requirements have
been demonstrated in poultry (1% DM [11.93 MJ ME/kg] for 0-12 weeks leghorn
chickens) (62). The diet of the Hyacinth macaw (Anodorhynchus hyacinthinus)
and the Lear’s macaw (A. leari) in Brazil contains predominantly SFA (3). A
study of the crop content of free ranging kakapo (Strigops habroptila) chicks
found 7.8% DM FA (41).
Macro and micro minerals
At least 13 minerals are required for the optimal health and productivity of
birds (26). Minerals that serve structural or osmotic functions are required in
relatively large amounts in the diet and are referred as the macrominerals: Ca,
P, Na, K, Cl and Mg. Minerals that are required at relatively low dietary
concentrations are referred as trace minerals: Cu, I, Fe, Mn, S, Se and Zn.
Beyond calcium, the requirement of psittacine birds for other minerals is
unknown (4). Calcium is a vital component of bone and body fluid, and is
important for chick growth (13). The requirement of calcium for growth has been
determined empirically for poultry; it decreases from 1.0% to 0.8% between 0
and 8 weeks showing that the requirement is higher early in life when the growth
rate is highest, and decreases in the adult bird. Previous research on scarlet
macaws chicks crop content found 1.4% Ca DM (40). Phosphorus is an
important constituent of bone, proteins, carbohydrates and lipid complexes (13).
Evaluation of the Ca:P ratio in the diet is important as excess P can inhibit the
uptake of calcium and result in bone growth abnormalities especially in growing
animals (6, 62, 84). To a lesser extent surplus Ca reduces P uptake (6, 85). In
leghorn chickens, the Ca to non-phytate P ratio increases from 2.2 to 2.7
between 0 and 8 weeks (62), while in the scarlet macaw crops was found to be
2.9 (40). The rate of skeletal growth of altricial hatchings is considerably faster
than that of precocial birds, but the requirement for Ca has not been
investigated. Presumably the combination of a faster growth rate and lower
9
calcification of the skeleton at hatching cause altricial species to have greater
requirements than precocial species (26).
Study species and sites
Five different Neotropical parrot species of three genera and from three
countries were used in this study.
Cuban parrot (Amazona leucocephala bahamensis)
This subspecies breeds in the Caribbean pine forests of Abaco island
[annual rainfall of 1,544 mm, monthly temperature means 21 27°C (86, 87)]. It
is known to feed on 24 plant species (9, 88). During the breeding season their
diet is predominately composed of Caribbean pine seeds and cones (Pinus
caribaea), poisonwood fruits (Metopium toxiferum) and wild guava (Tetrazygia
bicolor). According to extrapolations from observations of the feeding habits
during the nesting season, the Cuban parrots feed their chicks a diet containing
22.4% DM protein, 21.3% DM fat, and 10.1% DM ash (9).
Thick-billed parrot (Rhynchopsitta pachyrhyncha)
This species nests in the conifer forest of Sierra Madre Occidental of
western Mexico above 2,000 m elevation [annual rainfall 400 to 1,100 mm (89)].
This species nests during the peak in production of pine-seeds (90). The
quantitative analysis of 102 crops of 64 Thick-billed parrot nestlings in 35 nests
(27) showed that the chicks were fed pine seeds (86% by weight), bark (9%),
acorns (4%), insects (< 1%) and pine needles (< 1%).
Lilac-crowned parrot (Amazona finschi)
This species is endemic to the tropical dry deciduous and semi-deciduous
forest of the Pacific coast of Mexico (91) [average annual precipitation 748 mm
(92)]. This species feeds on more than 33 different plants during the year (7).
10
They exhibit high flexibility in their diet, being able to adjust for temporary
variations in the food resources (93). Their diet is composed of 82% seed, 9%
fruits, 7% insect larva, and 3% bromeliad stems (7).
Scarlet macaw
This species was studied at the Tambopata Research Center (TRC). TRC
is located in the lowland forests of south-eastern Peru. The center lies at the
boundary between tropical moist and subtropical wet forest at an elevation of
250 m, and receives 3,200 mm of rain per year. This species feeds on 73 food
species in the Amazonian rainforest of Peru (35, 94), 43 food species in tropical
forest of Costa Rica (95) and 15 plant species during the breeding season in
Belize (34). Crop samples from this species have been studied for nutritional
content in Peru (40), and species composition in Belize (34). The samples
contained a mixture of seeds, fruit, flowers, tree bark, insects, and in the case of
Peru, soil from river edge “clay licks” (96, 97).
Red-and-green macaw (Ara chloropterus): This species was studied at
the Tambopata Research Center (TRC). TRC is located in the lowland forests of
south-eastern Peru. In the Amazonian rainforest of Peru it is reported to feed on
> 56 food species (35, 94) and use clay licks .
Research objectives
To provide novel information on psittacine nutrition and generate
suggestions that help improve the hand rearing of this group.
Specific objectives:
Assess the feasibility of NIRS as a technique for the non-destructive, low
cost prediction of nutritional composition of very small samples of parrot
crop contents.
11
Document and compare the concentrations of predicted metabolizable
energy, crude protein, amino acid profiles, crude fat, FA profiles, fiber,
and minerals of the crop samples of chicks from five free-ranging
Neotropical parrot species.
Document the nutritional content and physical characteristics of the main
commercial parrot hand feeding products available in the U.S., and
compare them with the crop samples of five free-ranging Neotropical
parrot species.
12
CHAPTER II
PREDICTION OF THE NUTRITIONAL COMPOSITION OF THE CROP
CONTENTS OF FREE-LIVING SCARLET MACAW CHICKS BY NEAR-
INFRARED REFLECTANCE SPECTROSCOPY*
Synopsis
It is difficult to determine with accuracy the nutrition of bird diets through
observation and analysis of dietary items. Collection of the ingested material
from the birds provides an alternative but it is often limited by the small sizes of
samples which can be obtained. We tested the efficacy of near infrared
reflectance spectroscopy (NIRS) to assess the nutritional composition of very
small samples of growing parrot crop content. We used 30 samples of the crop
content of free-living scarlet macaw (Ara macao) chicks. Samples were scanned
with a Near-infrared Reflectance Analyzer, and later analyzed by traditional wet
lab methods for Crude Protein/N, Fat, Ash, Neutral Detergent Fiber, P, K, Ca,
Mg, Cu, Zn, and S. A calibration model was developed using principal
components analysis. Coefficients of determination in the calibration (R2) and
standard errors of cross-validation (SECV) for most of the nutrients showed a
good performance (average R2 of 0.91 ± 0.11 SD, n = 10) when excluding Zn
(R2 of 0.15, SECV = 25.37). These results establish NIRS as a valid technique
for the nondestructive, low cost prediction of a variety of nutritional attributes of
avian crop contents as small as 0.5 g dry weight. The use of NIRS expands the
possibilities of wild animal nutrition research.
____________
*Reprinted with permission from “Prediction of the nutritional composition of the
crop contents of free-living scarlet macaw chicks by Near-infrared Reflectance
Spectroscopy” by Cornejo, J., Taylor, R., Sliffe, T., Bailey C. A., and Brightsmith,
D. J. Wildlife Research, In press;39(3). Copyright 2012 by CSIRO PUBLISHING.
http://www.publish.csiro.au/nid/144.htm
13
Introduction
Knowledge of avian nutrition, as a component of both their ecology and
management, is central to understanding the survival and productivity of the wild
populations (6), and has a direct applications in ex situ husbandry (98). Through
foraging observations it is often possible to identify species’ main food sources,
but it is difficult to determine the less common items in the diet and quantify the
exact proportion of each food type consumed (8, 36). As a result, it is usually
impossible to determine the nutritional content of diets through just observation
and analysis of dietary items. However, a variety of techniques exist to collect
samples directly from the crops and stomachs of individual birds (36, 37).
Unfortunately, the small size of the individual samples greatly limits the
traditional wet lab analyses which can be done. Pooling samples of similar
characteristics is often necessary to achieve the minimum sample sizes needed
for analysis but this reduces statistical power needed to address ecological
hypotheses (40, 41).
Despite the high percentage of psittacine taxa threatened (99) there is a
dearth of studies regarding the nutrition of free ranging psittacines (4). This is in
part because the bird’s extensive food manipulation and processing makes it
very difficult to gather quantitative food intake data. Parrots feed their chicks
undigested regurgitate, so tube sampling the crop provides the opportunity to
determine the composition of the diet as fed and unaffected by differential
digestion (37, 40). However, individual crop samples are usually less than 1.5
grams dry weight while analyses such as proximal and mineral composition
commonly require 2.5 grams of sample each.
Near Infrared Reflectance Spectroscopy (NIRS) is an indirect method that
estimates chemical composition by comparing spectra of samples with known
composition to spectra of samples with unknown composition (100, 101). Near-
infrared radiation (750 - 2500 nm) is absorbed mainly by organic bonds (102).
The frequencies which match the vibrational waves of these bonds are
14
absorbed, whereas other frequencies are reflected or transmitted resulting in
NIR spectra which contain detail on the chemical composition of the material
(100). The advantages of NIRS are that it is nondestructive, has high precision,
produces no wastes, requires no costly reagents, needs minimal sample
preparation and a requires very small sample size (103).
NIRS is widely accepted for compositional and functional analyses in
agriculture and manufacturing (104, 105). It is widely used to predict a variety of
nutrients in leaves, grasses and grains (106, 107), including amino acids (108),
tannins and alkaloids (109), and mineral elements (110, 111). It has been
applied in the study of the foraging ecology and nutrition of several wild and
domestic herbivorous mammals through the analysis of their diets, excreta and
esophageal extrusa (112-114). In avian nutritional studies it only has been used
to predict the nutritional composition of feeds and excreta (115-118). In this
study we evaluated NIRS as a tool to assess the nutritional composition of small
dietary samples collected from wild avian species using crop content samples
from wild scarlet macaw chicks.
Methods
Sample description
This study analyzed the crop contents samples from free-living scarlet
macaw (Ara macao) chicks previously collected in Brightsmith, McDonald et al.
(40). Samples were collected during the 2005 breeding season at the
Tambopata Research Center in the lowland forests of southeastern Peru (13º
07 S, 69º 36 W; 250 masl). Crop contents were sampled following Enkerlin-
Hoeflich et al. (37). In this technique, the bird is hand restrained, the crop is
massaged, a flexible and lubricated plastic tube is inserted in to the crop through
the esophagus, the crop contents pushed up in to the tube, and the tube
removed. A total of 48 individual samples were obtained from 10 chicks found in
seven nests (average dry weight per sample 1.5 ± 0.9 g). Due to the small
15
samples 13 of the samples were analyzed as independent samples, while the
remaining 35 were grouped in 17 composite samples for analysis (average dry
weight 2.5 ± 1.6 g). Composite samples were created by combining samples
from chicks in the same nest collected on the same day or from chicks of similar
age. During preprocess examination of the crop samples it was determined that
they contained seeds, wood/bark, fruit pulp, insect larvae, and 19 % of them
contained clay (40). All samples were placed in refrigeration at 4°C within 30
minutes of collection. The samples were dried to a constant weight in an oven at
approximately 55°C (105), ground to a fine powder (< 1 mm particle size), and
stored in airtight containers until analysis.
Standard nutritional analysis
Proximate laboratory analyses were performed at the Palmer Research
Center at the University of Alaska. Crude protein was calculated using the
Dumas method (105) in a LECO CHN-1000 analyzer for carbon, hydrogen and
nitrogen. Crude fat was calculated using the ether extraction method (119).
Concentrations of Ca, K, P, Mg, Zn, Cu, and S, were determined by mass
spectroscopy (102) after wet ashing (120). Neutral detergent fiber (NDF) was
calculated by Van Soest’s detergent analysis system (121). Ash was calculated
by heating the sample to 550 oC for 12 hrs. All results are presented on a dry
matter basis (105).
Collection of spectral data
Each sample was scanned once with a Perten DA 7200 IR spectrometer
(Perten Instruments AB, Sweden). A mirror module was used to accommodate
the small sample. The window is made of sapphire, with a surface area of 25
cm2, with a 256 pixel Indium-Gallium-Arsenide (InGaAs) detector operating in
the wavelength range 900-1700 nm. The spectra were stored in optical
16
sensitivity units log (1/R), where R represents the percent of energy reflected
(Figure1).
Calibration set and model development
The multi-variant chemometrics package ‘Unscrambler’ (CAMO Software
Inc., Woodbridge, USA) was used to process the spectral data from the
samples. An independent calibration model for each nutritional attribute was
developed through Principal Component Analysis (PCA) (122, 123). To evaluate
the predictive power of the chosen model we determined the coefficients of
determination (R2) for each nutritional attribute, as a measure of the proportion
of variability explained by the regression model.
Validation set
Due to the reduced sample size, for validation of the calibration accuracy
we used the cross-validation method with samples from the initial data set (101),
avoiding the need to set aside samples for a validation set. The pooled residuals
of each prediction (standard error of cross-validation, SECV) were calculated to
evaluate the precision of the chosen equations for each nutritional attribute.
Results
The NIRS equations for all nutrients except Zn showed strong predictive
power. The R2 between the NIRS predictions and laboratory analyses were
above 0.85 for all nutritional variables tested, except Cu (R2 = 0.63) and Zn (R2 =
0.15) (Table 1).
17
Wavelength (nm)
950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650
Absorvance (Log (1/R))
-3
-2
-1
0
1
2
3
Fig. 1. Near infrared reflectance spectra (950 - 1650 nm) of crop samples from free-
ranging scarlet macaws (Ara macao) in southeastern Peru.
Discussion
Our study found that NIRS accurately predicted the nutrient contents of
the crop contents of scarlet macaw nestlings for 10 of 11 nutrients tested. These
results mirror those achieved with commercial plant species such as rice (124)
and oats (125), as well as wild plants consumed by mountain gorillas (Gorilla
beringei) (113), African ungulates (126), and wombats (Lasiorhinus krefftii)
(112).
Minerals are usually not well predicted by NIRS, unless they are part of
organic complexes or chelates, or if concentrations are correlated with other
18
constituents of the sample (109, 111). However, 6 of 7 minerals in our study
showed good correlations, and only Zn showed less than 0.60 R2 suggesting
that most of the minerals are bound organically.
Table 1. Nutritional values and calibration equation performance for crop samples from
free ranging scarlet macaw (Ara macao) chicks collected in southeastern Peru. NDF =
Neutral detergent fiber.
NDF
%
Ash
%
Fat
%
Prot.
%
K
%
Ca
%
Mg
%
Cu
ppm
Zn
ppm
S
%
Average
42.8
7.15
19.0
17.3
0.92
0.88
0.29
14.4
39.8
0.31
SD
26.46
5.71
13.4
11.8
0.50
1.06
0.28
4.99
10.7
0.45
R2
0.86
1.00
0.92
0.93
0.91
0.98
0.99
0.63
0.15
0.99
SECV
10.5
0.35
3.99
3.28
0.15
0.13
0.02
3.81
25.4
0.03
N
30
19
24
31
24
22
28
21
27
19
Our results show NIRS is a valid technique for the nondestructive, low
cost prediction of the nutritional composition of avian crop contents. NIRS can
be used with samples as small as 0.5 g dry weight, expanding the possibilities of
research in the nutrition of parrots and other animals where only small samples
are available. In our research we are using NIRS to increase the amount of
ecologically relevant information from our samples by 1) scanning individual
small samples with NIRS (as small as 0.5 g), 2) combining samples with similar
spectra into composite samples large enough for traditional laboratory analysis,
3) scanning these composite samples with NIRS, and 4) conducting laboratory
analyses on these composite samples. We can then use the lab analyses on the
composite samples to create the NIRS calibration curves and predict the
nutritional content of the individual small samples. In this way we can look at the
19
samples in individual scales, and test for nutritional differences among nest
mates, habitats, times of day collected, chick age, etc. with much finer resolution
than possible without the NIRS. Further studies should explore the possibilities
of using NIRS to identify the actual ingredients consumed by the birds (114).
Determining the key food resources on which avian species depend will help in
understanding their ecology and developing better management and
conservation strategies.
20
CHAPTER III
PREDICTED METABOLIZABLE ENERGY DENSITY AND AMINO ACID
PROFILE OF THE CROP CONTENTS OF FREE-LIVING SCARLET MACAW
CHICKS (Ara macao)*
Synopsis
Hand-rearing of neonates is a common practice for the propagation of
psittacines. However, nutritional requirements for their growth and development
are not well understood and malnutrition is common. We analyzed the amino
acid (AA) profile of the crop contents of 19 free-living scarlet macaw (Ara
macao) chicks, 19 to 59 days old. Predicted metabolizable energy (PME) density
was 16.9 MJ/kg DM, and true protein (total AA protein) 8.3 g/MJ PME. Crude
protein (CP) was 10 g/MJ PME, lower than the requirements of 0 to 12 wk old
leghorn chicks. The mean concentrations of leucine, isoleucine, threonine,
lysine, and methionine on a PME basis were below the minimum requirements
of 0 to 12 wk leghorn-type chicks. The calculated PME density of the samples
did not vary with age. However there was a significant negative correlation
between the average age of the chicks and the lysine concentration. We
conclude that the lower CP and amino acid densities in parrot chick crop
contents, compared with poultry, could result from a combination of: 1)
differences in the essential amino acid composition of the body tissues, 2)
adaptations which allow the birds to grow on low protein food sources, and 3)
suboptimal nutrition of these free ranging chicks.
____________
*Reprinted with permission from “Predicted metabolizable energy density and
amino acid profile of the crop contents of free-living scarlet macaw chicks (Ara
macao) by Cornejo, J., Dierenfeld, E. S., Bailey, C. A., and Brightsmith D. J.
Journal of Animal Physiology and Animal Nutrition. In press. Copyright 2011 by
John Wiley & Sons, Inc.
21
Introduction
Despite the increasing volume of research on the nutritional requirements
of psittacines (4, 17, 54), malnutrition is still a major concerns for the care and
propagation of this group (4, 24). Studies of the diet and nutrition of free ranging
psittacines are scarce (8, 9, 34, 41, 127-130), in part because the bird’s
extensive food manipulation and processing make it very difficult to gather
quantitative food intake data.
Hand rearing of neonates is a common practice for the propagation of
psittacines, both for the pet industry (44) and for conservation aviculture (46, 48,
50). However the nutritional requirements for the growth and development of
neonates are not yet well understood (4, 54, 56, 79), and imbalances are still
common (4). Only a few studies have looked at the nutritional content of diets
consumed by parent-fed psittacines chicks (40, 41), and the diversity of food
habits and ecology among psittacines makes it tenuous to extrapolate from
these limited studies to requirements for the Family as a whole.
In growing birds dietary protein is used for tissue accretion and
maintenance. The amino acid (AA) balance needed for growth closely mirrors
the AA composition in tissues (26). The tissue AA composition of different
species is relatively similar, so the difference in AA requirements is mainly driven
by the different fractional growth rates (26). Amino acid requirements have been
studied extensively in commercial fowl (62, 77, 78). However, psittacines have
received limited attention with most studies focused on adult maintenance
requirements (15, 17, 19, 79) and only a few data available on growth
requirements (4, 54, 56, 79). In the absence of controlled studies of
requirements or comprehensive data on the diets of wild birds, nutritional
prescriptions for psittacine growth and maintenance are generally extrapolated
from dietary recommendations for poultry (4). However, psittacines are not
closely related to poultry and differ both developmentally (63) and ecologically
22
(64), so it is questionable if the available data adequately model their dietary
requirements.
The metabolizable energy (ME) densities of diets are the primary factor
which determines the amount of food an animal will consume (26). Expressing
nutrient concentrations on a per energy basis allows for more meaningful
comparison among diets even when the ingested amounts are not known (26).
Brightsmith et al. (40) studied the nutritional content of 30 crop samples of
scarlet macaw chicks 28 to 60 days post hatch at the same study site. Crude
protein, crude fat and mineral concentrations were reported, but neither the AA
profile or the ME were described.
The present study provides the first estimates of the ME density and AA
profile of free ranging Neotropical parrot chicks. The objectives are (1) to
characterize the AA profile and ME concentration of the crop content of wild
scarlet macaw (Ara macao) chicks, and (2) to compare the AA and ME levels of
the crop contents with nutritional information from other psittacines and the
domestic chicken.
Methods
Crop samples
We collected crop contents from free-living scarlet macaw chicks 19 to 59
days post hatch from Tambopata Research Center in the lowland forests of
south-eastern Peru (13º 07 S, 69º 36 W; 250 m elevation). In this region,
parrots and macaws consume a diverse mixture of seeds, fruit, flowers, tree
bark and soil from river edge “clay licks” (96). Once every 7 to 10 days, crop
contents were collected from chicks in nests of wild macaws following the
procedures in Enkerlin-Hoeflich et al. (37). Samples were placed in refrigeration
at 4°C within 30 minutes of collection. In the 2006 breeding season a total of 38
samples were collected from 10 chicks (mean dry weight per sample 2.4 ± 2.3
g). During the 2008 breeding season a total of 18 samples were obtained from 9
23
chicks (mean dry weight per sample 1.2 ± 1.1 g). All sampled chicks appeared in
good health and fledged at appropriate ages for the species (61). Due to the
small quantity of each sample, we pooled samples for analysis. For 2006 a total
of 15 composite samples were created by combining samples from chicks in the
same nest collected on the same day or from chicks of similar age. The 2008
samples were scanned with a near infrared reflectance spectroscope (Perten DA
7200 IR, Perten Instruments AB, Sweden, for more details see Cornejo et al.
(131), and pooling was done according to the similarity of their spectra.
Chemical analysis
Samples were freeze-dried and ground. The crude nutrients were
analyzed at the Palmer Research Center at the University of Alaska. N was
determined by the Kjeldahl method, crude fat was calculated using the ether
extraction method (119), NDF was calculated by Van Soest’s detergent analysis
system (121), and ash by high temperature ashing (105). True protein was
determined as the total AA concentration (132), and crude protein by multiplying
total N by a 6.25 factor (133). Soluble carbohydrates were calculated by
difference following the formula: % soluble carbohydrates = 100 % crude
protein % crude fat % ash % NDF. True protein, crude protein (CP), and
AA concentration are presented as g/MJ predicted metabolizable energy (PME)
for comparison among diets and species. PME values of the crop contents of the
scarlet macaws and the kakapos, as well as the diet of leghorn chickens,
budgerigars (Melopsittacus undulatus) and lovebirds (Agapornis spp.) were
calculated using the formula PME (kJ/100 g DM) = (18.4 x CP) + (36.4 x crude
fat) + (16.7 x soluble carbohydrates) (21, 62). Average true and crude protein
level are also presented as % DM.
Macaws at the study site feed soil to their chicks (40) but the amount of
soil varied among samples (40) and the soil may have led to inflated NDF values
due to filtration issues (121). In order to calculate PME using the equation
24
above, we corrected the NDF values for each sample by subtracting the
estimated amount of soil ash from the original NDF value. The percent soil ash
in each sample was estimated as the total ash minus the average ash content
from samples known to contain no soil (6.2 ± 1.4 %, N = 8). We took into
consideration that the average ash content of 6.2% is similar to the average ash
for natural foods consumed by scarlet macaws in Peru (5.7 ± 3.4 %, N = 17,
Brightsmith, unpublished data).
Complete AA analysis was performed in the Amino Acid Laboratory of the
Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis.
The majority of the essential AAs were analyzed using the Association of Official
Analytical Chemists (AOAC) modified method 994.12 (105). Protein hydrolysate
was prepared by treating 10-mg finely grinded sample with 2.0 ml of 6 N HCl in a
10 ml evacuated ampule (Wheaton Prescored Gold-Brand, Fisher Scientific Cat
No. 12-009-38) for 24 h at 110°C. After flash evaporation using nitrogen gas, the
dried residue was dissolved in Biocrom loading buffer. Aliquots were analyzed
by ion-exchange chromatography using an LKB Biochrom 30 automatic amino
acid analyzer. Methionine (Met) and cystine (Cys) were analyzed separately
(AOAC Method 994.12). After performing acid oxidation and subsequent
hydrolysis with 6 N HCl, Cys and Met were determined by measuring cysteic
acid and methionine sulfone using a Biochrom 30 amino acid analyzer.
Tryptophan (Trp) was determined by AOAC method 988.15. After alkali (LiOH)
hydrolysis, the quantification was performed using the Biochrom amino acid
analyzer. As part of the QA/QC procedure, 1000 nmol/ml of norleucine was
included in 6 N HCl as internal standard and casein powder of known AA value
was used as reference sample to evaluate the hydrolysis and the
chromatography procedures. To determine the reproducibility of the assay, four
replicates were assayed using a casein control sample. On average, 99.2% of
the sample was recovered, and the CV of the means was below 5% for most of
25
the AAs, except for serine (Ser) and Proline (Pro) (6%), Glycine (Gly) (8%),
aspartic acid (Asp) (9%) and Cys (15%).
Published requirements and crop content of other species
For comparison with our results we compiled the published CP and AA
requirements for optimal growth of leghorn chickens age 0 to 6 and 6 to 12
weeks (62), broiler chicks 0 to 3 wk old (134, 135) and 3 to 8 wk old (136), and
budgerigars and lovebirds estimated using the factorial method (56). We
compared our average protein and AA concentrations from crop samples with
the pooled crop contents of 15 free ranging kakapo (Strigops habroptila) chicks
from 10 nests (age 10 to 43 days). The kakapos are phylogenetically far from
the macaws (64) and very specialized herbivores, who feed their chicks almost
exclusively rimu fruits (Dacrydium cupressinum), but it is the only other species
of psittacine in which AA profile of the crop contents of parent-reared chicks
have been published (41).
Statistical analysis
Mann-Whitney U tests were used to compare the levels of total protein
and AAs in the scarlet macaw crop samples between years, and to compare the
concentration of ash with the findings of a previous study. One-sample t-test was
used to compare the crop nutrient levels with the published requirements for
poultry and other psittacine species, and with the average levels found in the
kakapo crop contents (41, 54, 56, 62). Linear correlation was used to determine
the relation between the average age of the chicks in each sample with the
concentration of PME, protein and AAs. Linear correlation was also used to look
at the relation between the concentration of protein and of each AA. Statistical
tests were conducted by using JMP software (version 8.02; SAS Institute Inc.,
Cary, NC) with α = 0.05. Data are presented as mean ± standard deviation
(minimum maximum).
26
Results
Predicted metabolizable energy
The scarlet macaw chick crop contents contained, on average, 16.3 ±
4.3% DM (10.4-23.8) crude protein, 22.0± 5.6% DM crude fat, and 37.7± 17.3%
DM soluble carbohydrates. The PME density was 16.9 ± 2.6 MJ/kg DM (10.2-
19.7). Energy density was not significantly different from commercial diets
offered to leghorn chicks (p > 0.05) (62), nor the average of 11 parrot hand
feeding formulas (16.2 MJ PME/kg, t = 2.60, df = 14, p < 0.05) (56), but was
significantly higher than the 7.7 MJ PME/kg received by kakapo chicks (t = 5.56,
df = 14, p < 0.001) (41).
Crude and true protein
The mean true protein content, calculated as the sum of the AAs (105),
was 13.6 ± 3.9% DM (7.5-20.6), and 8.3 ± 2.9 g/MJ PME (4.1-13.7, N = 15
pooled samples) (Table 2), with no significant differences between years (U =
10.0, p > 0.05). The CP content was 10.0 ± 3.5 g/MJ PME (5.8-16.9, N = 15
pooled samples). The mean CP content, on a PME basis, was lower than the
requirements of 0 to 6 wk old leghorn chicks (16.6 g/MJ PME; t = 7.33, df = 14, p
< 0.001), and 6 to 12 wk old leghorn chicks (14.7 g/MJ PME; t = 5.23, df = 14, p
< 0.001) (62). It was not different than the requirements of budgerigars (10.2
g/MJ ME; t = 0.24, df = 14, p > 0.05) and lovebirds (9.5 g/MJ ME; t = 0.54, df =
14, p > 0.05) (56), nor the concentration found in the crop of wild kakapo chicks
(10.9 g/MJ PME, t = 1.01, df = 14, p > 0.05) (41).
Amino acid profile
The concentrations of the AAs in the crop contents of the scarlet macaws
did not differ significantly between years except for Cys, which was 0.25 g/MJ
PME in 2006 and 0.05 g/MJ PME in 2008 (U = 0.00, P < 0.01). As a result,
27
Table 2. Crude protein and amino acid composition in g/MJ PME of crop contents of free-living scarlet macaw chicks (Ara
macao), crop contents of kakapo (Strigops habroptilus) chicks, and the nutritional requirements of budgerigars (Melopsittacus
undulatus), lovebirds (Agapornis spp.), and leghorn chickens, (Gallus gallus).
Scarlet macaw 1
Kakapo 2
Budgerigar3
Lovebird 3
Leghorn chickens4
Item
0-6 wk
6-12 wk
g/MJ
PME
SD
range
g/MJ PME
g/MJ ME
g/MJ ME
g/MJ
PME
g/MJ
PME
Crude protein
9.99
3.49
5.81-16.9
10.9
10.2
9.48
16.6*
14.7*
Arginine
0.88
0.32
0.43-1.49
1.30*
0.52#
0.46#
0.92
0.77
Leucine
0.60
0.22
0.31-1.01
0.82*
1.01*
0.78*
Valine
0.53
0.21
0.22-0.90
0.63*
0.57
0.48
Phenylalanine
0.41
0.15
0.18-0.63
0.50*
0.54*
0.41
Phe + Tyr
0.69
0.24
0.34-1.08
0.83
0.92
0.77
Isoleucine
0.36
0.14
0.18-0.61
0.51*
0.55*
0.46*
Threonine
0.36
0.14
0.17-0.61
0.38
0.63*
0.53*
Lysine
0.36
0.15
0.20-0.72
0.61*
0.33
0.32
0.78*
0.55*
Methionine
0.17
0.06
0.10-0.31
0.24*
0.28*
0.23*
Met + Cys
0.396
0.14
0.21-0.72
0.51
0.50
0.37
0.57
0.48
Tryptophan
0.08
0.04
0.03-0.14
Proline
0.42
0.15
0.18-0.68
0.54*
0.16#
0.13#5
Glycine
0.40
0.15
0.19-0.67
0.55*
Histidine
0.23
0.08
0.12-0.36
0.38*
0.24
0.20
Glutamic acid
1.32
0.48
0.65-2.24
1.81
28
Table 2. Continued
Scarlet macaws 1
Kakapo 2
Budgerigar3
Lovebird 3
Leghorn chickens4
Item
0-6 wk
6-12 wk
g/MJ
PME
SD
range
g/MJ
PME
g/MJ ME
g/MJ ME
g/MJ
PME
g/MJ
PME
Aspartic acid
0.73
0.35
0.39-1.33
1.23
Alanine
0.47
0.17
0.24-0.82
0.58
Serine
0.43
0.16
0.22-0.67
0.54
Gly + Ser
0.83
0.30
0.41-1.34
1.09
0.65
0.53
Tyrosine
0.28
0.09
0.16-0.48
0.33
Cystine
0.216
0.11
0.04-0.42
0.26
Hydroxyproline
0.02
0.03
0.00-0.10
Citruline
0.02
0.02
0.00-0.07
1 Chick crop contents, n = 15, 3-8 wk old, 16.87 ± 2.62 MJ PME/kg, total AA protein = 8.29 g/MJ PME
2 (41) mean chick crop contents. 7.67 MJ PME/kg
3 (56) minimum growing requirements. 16.22 MJ ME/kg
4 (62) 11.93 MJ PME/kg
5 (137)
6 Significant differences between years (U = 0.00, p < 0.001). Cys average 2006 = 0.25 g/MJ PME, 2008 = 0.05 g/MJ PME
*Values significantly higher than the scarlet macaw crops (p < 0.05)
# Values significantly lower than the scarlet macaw crops (p < 0.05)
29
values for all AAs are combined across years for the remaining analyses. The
AAs present in the highest concentrations were glutaminc acid (Glu 1.32 g per
MJ ME), arginine (Arg 0.88 g), aspartic (Asp 0.73 g), and leucine (Leu 0.60 g)
(Table 2). There was a strong positive correlation (p < 0.001) between the
concentration of each essential amino acid (EAA) and the total protein content
(as g per MJ PME). The mean concentrations of five EAAs were below the
minimum requirements established for leghorn-type chicks aged 6 to 12 wk: Leu
(76% of recommended), isoleucine (Ile 79%), threonine (Thr 69%), Lys (65%)
and Met (75%). In addition phenylalanine was also below the minimum
requirement for leghorn-type chickens 0 to 6 wk old (75%) (62) (Table 2). None
of the EAAs were found in concentrations below the minimum requirements of
budgerigars and lovebirds (56). The kakapo chick crops had higher
concentrations of all the EAAs except for Thr (41).
Age variations
There was no significant correlation between the age of the chicks and
the PME of the samples, the total protein content as percent DM or the protein in
g/MJ PME (R < 0.24, p > 0.05, N = 12). However, a significant negative
correlation was found between the age of the chicks and the concentration of
Lys (R = 0.56, p = 0.005, N = 12) and Met (R = 0.34, p = 0.044, N = 12).
Discussion
The PME density of the regurgitate fed to the scarlet macaw chicks was
equivalent to a starter poultry feed (62), and higher than the low quality food
used by the kakapo to feed their chicks (41). The daily energy requirements of
growing birds change as a function of weight gain rate and body composition
(26, 138).As anticipated, the PME density of the diet fed to the scarlet macaw
chicks did not change with age(139).
30
Our samples contained 16.3% CP on a DM basis. A previous study of
scarlet macaw chick crop samples from the 2005 breeding season in the same
study site found 23.5 ± 5.6% CP (DM basis) (40). We suspect that the difference
was not due to annual variations in the composition of available food items, as
the weather patterns did not differ greatly between years (Brightsmith,
unpublished data). One possible explanation is that the samples from 2005 had
lower clay content, which increased the relative concentration of CP on a DM
basis. This is supported by the lower ash concentration (DM basis) of the 2005
samples vs. 2006 and 2008 samples (11.7 ± 8.7%, Brightsmith, unpublished
data, vs. 26.3 ± 18.9%, U = 5.84, p < 0.05, respectively). It was not possible to
calculate PME of the diet in that original study however, so we can’t determine if
there is also a difference on an energy density basis.
The CP values found in the scarlet macaw crop samples were lower than
expected based on the estimated requirements of leghorn chickens (62), but in
line with the requirements estimated for cockatiels and lovebirds (56) and the
concentrations found in kakapo chicks (41). We expected that macaw chick
dietary protein levels would be higher than those of poultry due to their altricial
development and higher growth rate (4). However, birds don’t have a CP
requirement per se; instead the requirements depend on protein quality, i.e. the
concentrations of EAAs and protein digestibility (26, 80). The complexity of the
AAs interrelationships makes it difficult to define a protein requirement for any
species, and the evaluations should be limited to comparing typical protein
intake values among species (25).
The wild diet seems to contain a moderate level of non-protein nitrogen,
as indicated by the difference between the crude protein (10.0 g/MJ ME) and the
total AA concentration (8.3 g/MJ ME). The CP estimation obtained by multiplying
N by the widely used value of 6.25 (133) is 20% higher than the total AA
concentration. If summed AA are an accurate reflection of CP, this suggests that
31
the appropriate N:protein conversion factor for true protein would be closer to
5.20, in the range of the 5.18 to 5.46 as proposed for nuts and seeds (140).
The concentrations of half of the EAA found didn’t fulfill the requirements
of growing 6 week old leghorn chicks. Normally, the profile of EAAs required by
birds corresponds to that found in the body tissues (141). The lower densities in
the diet of the scarlet macaw compared with the requirements of poultry could
be driven by differences in the EAAs composition of the body tissues compared
with precocial birds (142, 143). However, the bodies of adult budgerigars and
chickens have similar AA profiles (81), and there is no reason to believe that
body of scarlet macaws should have a significantly different composition.
Deviations from a one-to-one relationship between body and required dietary
EAAs can be caused by (a) different turnover rates of individual tissue proteins
(77), (b) different digestibilities and efficiencies of reutilization of the EAAs (144),
or (c) alternative metabolic fates of different EAAs (145, 146). More studies of
the AA metabolism of the scarlet macaw are needed to better understand the
apparently low concentrations of EAAs in the diets found here.
We found a 38% decrease in Lys from age 19 through 59 days post
hatch. As the chick grows, protein gain as a percentage of total body weight gain
decreases, as do the requirements for muscle accretion (62, 77, 136). Around
the fourth week post hatch, when the chick starts to grow the flight feathers
(147), the AA composition of the body protein changes, decreasing the relative
concentration of total Lys and increasing Cys (138, 148). If this relationship
holds for scarlet macaws as well, this mechanism could help explain the
decrease in Lys found here.
In summary, our research suggests that young scarlet macaws at our site
are being fed a diet with a PME protein and EAA concentration similar to the
requirements estimated for other psittacines, but lower than the requirements for
poultry. Here we discuss two possible explanations for this finding. One
possibility is that the birds evolved to raise chicks on low protein food sources.
32
Adaptations to low protein food sources include low endogenous protein losses
and low protein maintenance requirements. In psittacines, these mechanism
have been found in strict frugivores including Pesquet’s parrots (Psittrichas
fulgidus) (17), rainbow lorikeets (Trichoglossus haematodus) (149), and
kakapos. Adult kakapos are known to subsist during the nonbreeding period on
a diet of 3.7% DM CP (150). They feed their chicks a diet almost exclusively of
Dacrydium cupressinum fruit, which is relatively high in indigestible matter and
low in CP (10.9 g/MJ PME, 8.4% DM) and other essential nutrients (Table 2)
(41). Future research may look at the nitrogen balance of the scarlet macaws, to
determine if their physiology is adapted to a low protein diet.
A second possible explanation for the low protein and EAAs
concentrations is that the chick diets we studied are not sufficient to promote
optimal growth. Experiments with cockatiels have shown that optimum growth is
achieved at 20% DM CP and 0.8% DM Lys. However it was not until diets were
below 10% DM CP that permanent damage or mortality occurred (54). The
macaw chicks at our site fledge successfully and the populations are apparently
not decreasing (Brightsmith, unpublished data). However, chick growth rate
does not reach the maximum possible for the species as evidenced by the
higher growth rates found in other wild populations (93) and hand-raised birds
(3, 61, 151). Previous work in this population suggested that the concentration of
Na in the chicks’ diet may be deficient (40). Our current study suggests that
several EAA may also be acting as growth-limiting factors, as has been
proposed for other free-ranging parrots (71, 93, 152). As a result, the amino acid
profiles presented here should be used with caution when formulating hand-
rearing diets for macaws and other psittacines.
33
CHAPTER IV
FATTY ACID PROFILES OF CROP CONTENTS OF FREE-LIVING
PSITTACINES AND IMPLICATIONS FOR HAND-FEEDING
Synopsis
Research on psittacine nutrition is limited and the chicks requirements
are poorly understood. Although crude fat is recognized as an important energy
component in the formulation of parrot hand-rearing products, fatty acid (FA)
profiles have received little attention. To better understand the natural nutrition of
psittacines chicks, we analyzed the FA profiles of the crop contents of free-living
scarlet macaws (Ara macao), red-and-green macaws (A. chloropterus),Cuban
parrots (Amazona leucocephala bahamensis), lilac-crowned parrots (A. finschi),
and thick-billed parrots (Rhynchopsitta pachyrhyncha). We also analyzed 15
commercially available hand-feeding formulas for parrots. The total FA
concentration of the crop samples ranged from 12 to 21% dry matter (DM), and
in all cases, values were higher than the average in the hand-feeding formulas.
The profiles of all crop samples and formulas were dominated by long-chain FA.
For both crop samples and formulas the saturated fatty acids (SFA) were
dominated by palmitic and stearic acid, the monounsaturated fatty acids (MUFA)
by oleic acid, and the polyunsaturated fatty acids (PUFA) by linoleic acid. PUFA
were largely dominated by the n6 family, both in the crop samples (7-108:1), and
the formulas (15:1). Manufacturers should evaluate if the following profiles
improves the performance of their formulas: at least 12% DM long-chain FA and
~20-30% SFA for all species, with the diets for Ara spp. and Rynchopsitta sp.
containing 10-25% MUFA and 55-70% PUFA, and the diets for Amazona spp.
containing 25-40% MUFA, and ~40% PUFA.
34
Introduction
The hand-rearing of psittacine chicks is commonly undertaken in the pet-
trade (65) and for conservation (46, 48). However, the nutritional requirements of
psittacine chicks are poorly understood (4). Nutritional imbalances have been
common, and stunted development, rickets, and vitamin deficiencies still occur
for some species (4, 5). Hand-feeding diets have generally been extrapolated
from dietary recommendations for poultry (62) and modified based on trial and
error rather than on scientific study (4).
In recent years there has been a considerable increase in research on the
nutritional requirements of psittacines (4, 17, 54); however, the difficulty of
gathering quantitative food intake data has prevented more studies of the
nutrition of free ranging-psittacines, and most have focused on Austral-Asian
species (8, 9, 34, 41, 127-130), The nutritional composition of the diets
consumed by parent-fed scarlet macaws (Ara macao) from southeastern Peru
has been the focus of previous studies (40, 42), but fatty acid (FA) profiles have
not been reported. To our knowledge, only one previous study has detailed the
FA profile of the diet consumed by a parent-fed psittacines chicks, the kakapo
(Strigops habroptila) from New Zealand (41).
Crude fat is recognized as an important energy component in the
formulation of parrot hand-rearing products, yet FA profiles have received little
study. FA are central constituents of dietary lipids as providers of energy,
regulators of cell membrane integrity, and precursors of signaling molecules
(153), however the individual FA requirements and the ideal FA profile are
unknown not only for psittacines but for nearly all birds (4). In poultry nutrition,
linoleic and α-linolenic acids are recognized as metabolically essential FA (EFA),
serving as precursors of other (n-6) and (n-3) PUFA respectively (154).
Deficiency of EFA in chicks causes retarded growth and reduces resistance to
diseases (155). Some PUFA derived from the EFA are transformed into
eicosanoids that play key roles in the development and immunological
35
responses of growing chicks (154). A diet high in (n-3) PUFA results in the
reduction of the anti-oxidative status of broiler chickens (156). The intake ratio of
(n-6) to (n-3) PUFA influences the types and amounts of eicosanoids produced
in mammalian inflammatory and immune cells (157). A balanced intake of (n-6)
and (n-3) PUFA is recommended for poultry in order to maintain the full
spectrum of ecoisanoid effects in the body (62). Poultry growth requirements for
linoleic acid are satisfied by feeding 1% dry matter (DM) (62), and excessive
amounts may result in nutritional encephalomalacia (158). There is no known
specific avian dietary requirement for α-linolenic acid (155), although high
dietary intake has been suggested as a protective measure against the
development of nutritional encephalomalacia in chickens (158) and
atherosclerosis in parrots (159).
To gain a better understanding of parrot chick nutrition, we determined
the FA compositions of the crop contents from chicks of five free-living
Neotropical psittacine species. We also determined the FA composition of 15
commercial hand-feeding formulas. We compared FA concentrations for free-
living psittacines and hand-feeding formulas with regard to general profiles,
chain length, degree of saturation, and balance between (n-6) and (n-3) FA.
Methods
Crop samples
We collected crop contents from five species of free-living parrots: scarlet
macaw (Ara macao) and red-and-green macaw (A. chloropterus) from the
Tambopata Research Center in the lowland forests of southeastern Peru,Cuban
parrot (Amazona leucocephala bahamensis) from the Abaco National Park on
the Abaco Island of the Bahamas, lilac-crowned parrot (A. finschi) from the
Chamela-Cuixmala Biosphere Reserve in northwest Mexico, and the thick-billed
parrot (Rhynchopsitta pachyrhyncha) from the north of Mexico (Table 3). The
scarlet macaw and the red-and-green macaw are reported to feed on 55 and 51
36
plant species respectively in the Amazonian rainforest of Peru (160), while the
diet of the lilac-crowned parrot comprises 33 plant species in the tropical dry
forest of Mexico (27). The breeding diet of both the Cuban parrot (J. Cornejo
pers. obs.) and the thick-billed parrot (27) consists of 9 plant species.
Samples were collected following the procedures in Enkerlin-Hoeflich et
al. (37) and placed in refrigeration at 4°C within 30 minutes of collection, and
frozen at -4°C until analysis. All sampled chicks appeared in good health and
fledged at appropriate ages for the species (61, 93). Because of the small size of
each sample, we pooled samples for analysis (Table 3). Composite samples
were created by combining samples collected from chicks in the same nest on
the same day or from chicks of the same species in the same season.
Sample preparation and analysis
Samples were freeze-dried and ground with a mortar and pestle to a fine
powder. FA profiles were determined at the Comparative Animal Research
Laboratory, College of Veterinary Medicine and Biomedical Sciences, Texas
A&M University. The dried samples were extracted using a modification of the
Folch method (105) and total lipid concentration determined gravimetrically
(161). Total lipid FA methyl esters were prepared and then fractionated by thin-
layer chromatography on Silica Gel-G coated glass plates according to Bauer et
al. (162). Samples were recovered using a 50:50 (v/v) mixture of hexane:dietyl
37
Table 3. Parrot crop samples used for this study. Scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus),Cuban parrot (Amazona leucocephala bahamensis), lilac-crowned parrot (Amazona finschi), thick-billed parrot
(Rhynchopsitta pachyrhyncha), kakapo (Strigops habroptila).
Species
Source
Breeding
season
#
chicks
Average
age in days
(range)
#
nests
#
original
samples
Original
samples mean
dry weight in g
(SD)
#
pooled
samples
Scarlet macaw
Southeastern Peru
2006
9
42 (26-59)
6
20
4.08 (2.10)
12
2008
9
63 (20-86)
6
26
1.01 (0.76)
3
Red-and-green macaw
Southeastern Peru
2009
1
64 (32-96)
1
10
1.76 (1.20)
3
2011
4
46 (27-74)
2
14
1.63 (1.84)
4
Cuban parrot
Abaco Island,
Bahamas
2010
27
23 (14-37)
17
35
0.73 (0.45)
5
Lilac-crowned parrot
Western Mexico
2010
15
41 (27-60)
7
44
0.82 (0.46)
6
Thick-billed parrot
Northern Mexico
2010
13
55 (52-58)
8
13
0.70 (0.34)
2
38
38
ether, and FA profiles were determined using an OmegawaxTM 320 fused silica
capillary as described previously (161).
FA content is presented on a DM basis as well as on a metabolizable
energy (ME) basis. Predicted metabolizable energy (PME) values of the crop
contents were calculated using the formula PME (kJ/100 g DM) = (18.4 x crude
protein) + (36.4 x crude fat) + (16.7 x soluble carbohydrates) (21, 62). The crude
nutrients were analyzed at the Palmer Research Center at the University of
Alaska. N was determined by the Kjeldahl method, crude fat was calculated
using the ether extraction method (119), neutral detergent fiber (NDF) was
calculated by Van Soest’s detergent analysis (121), and ash by high
temperature incineration (105). Crude protein was determined by multiplying
total N by a 6.25 factor (133). Soluble carbohydrates were calculated by
difference following the formula: % soluble carbohydrates = 100 % crude
protein % crude fat % ash % NDF. Total FA are presented as g/MJ
predicted metabolizable energy for comparison among species.
We compared the results with the FA profiles of 15 commercial parrot
hand-feeding formulas from 10 different manufacturers (for more details on
these formulas, see Chapter V of this dissertation), the previously reported
composition of the crop of free-living kakapos chicks (41), the most common
food items in the diet of the hyacinth macaw (Anodrorhynchus hyacinthinus) and
the Lear’s macaw (Anodrorhynchus leari) (130), the commercial poultry food
(163-165), and the most common oils used in animal food industry (166).
Results
Fatty acid profiles
The mean percent FA of the crop contents ranged from 15 to 32% DM (9
to 15 g/MJ ME). In all cases, mean total FA of the five free-living Neotropical
psittacines were higher that determined in the kakapo chicks’ diet (41), and in
the average for hand-feeding formulas (Table 4). Highest concentrations of total
39
Table 4. Total fatty acid (FA) and crude fat content in crop contents from the five studied free-living psittacine species, the
kakapo (41), 15 commercial hand-feeding formulas (Chapter V), and the preferred food of the free-ranging hyacinth macaw
(130). Data expressed as average ± SD (range). Values in % of dry matter and in g/MJ metabolizable energy. Scarlet macaw
(Ara macao), red-and-green macaw (Ara chloropterus),Cuban parrot (Amazona leucocephala bahamensis), lilac-crowned
parrot (Amazona finschi), thick-billed parrot (Rhynchopsitta pachyrhyncha), kakapo (Strigops habroptila).
Scarlet
macaw
(n = 14)
Red-and-green
macaw (n = 5)
Cuban
parrot (n = 5)
Lilac-crowned
amazon (n = 6)
Thick-billed
parrot (n = 2)
Kakapo
(n = 2)
Commercial
formulas
(n = 15)
Acuri and
Bocaiuva
Crude fat (%DM)
21.6 ± 6.42
(9.53-29.42)
37.7 ± 10.4
(24.1-36.8)
30.5 ± 1.46
(29.2-32.5)
33.8 ± 8.9
(22.5-47.5)
41.4 ± 1.56
(40.3-42.5)
-
11.6 ± 4.61
(7.34-23.6)
Crude fat (g/MJ ME)
12.4 ± 3.10
(6.34-17.7)
18.6 ± 4.06
(13.0-23.8)
15.9 ± 0.57
(15.2-16.5)
15.3 ± 2.86
(11.5-19.4)
18.6 ± 4.06
(13.0-23.8)
-
6.73 ± 2.10
(4.55-11.5)
Total FA (% DM)
15.0 ± 5.17
(7.30-24.7)
30.9 ± 5.51
(25.4-36.8)
19.0 ± 2.74
(16.0-21.0)
24.8 ± 4.22
(19.1-29.9)
31.8 ± 0.56
(31.2-32.3)
7.81 ± 0.11
(7.73-7.89)
10.4 ± 4.05
(5.90-22.0)
(60.7-
66.4)
Total FA (g/MJ ME)
8.72 ± 3.07
(5.87-15.8)
15.3 ± 1.81
(13.3-17.5)
9.91 ± 1.40
(8.29-11.3)
11.3 ± 1.21
(9.78-12.7)
14.2 ± 0.24
(14.1-14.4)
10.2 ± 0.32
(9.96-10.4)
6.05 ± 1.92
(3.62-10.7)
40
40
FA were presented by the thick-billed parrot, the lilac-crowned parrot, and the
red-and-green macaw exceeding even the high-end of the range of total FA for
the 15 formulas (Table 4). All but one formula were below the mean total FA
concentrations found in the scarlet macaw and in the Cuban parrot. By
comparison, the main food plants of the hyacinth macaw had total FA
concentrations of 61-66% DM (130), far higher than that presented by the five
free-ranging Neotropical psittacines analyzed or the hand-rearing formulas
(Table 4).
The profile of all crop samples was dominated by long-chain FA (14-22
carbons, Table 5), with average long-chain FA values ranging from 96% total FA
in the Cuban parrot to 99.9% in the red-and-green macaw. No short-chain FA
(less than 6 carbons) were found in any of the crop samples. Medium-chain FA
(6-12 carbons) and very-long-chain (> 22 carbons) FA were also largely absent
from the crop samples (Table 5), the only exception being the Cuban parrot with
4% very-long-chain of total FA in samples (Table 5). The hand-feeding formulas
were also dominated by long-chain FA (> 81% FA, Table 5), did not contain
short-chain FA, had very small amounts of very-long-chain FA (< 0.8%), and
only three products contained mediumchain FA (10-18%). As for the other
psittacine species analyzed, the main food plants of the hyacinth macaw (16)
were predominantly long-chain FA (58-70%), though medium-chain FA occurred
in a greater proportion (30-42%) than that found in the other free-living
psittacines or in formulas (Table 5).
Parrot crop samples differed in saturation profiles by species. Crop
contents of the thick-billed parrot, red-and-green macaw, and scarlet macaw
were dominated by PUFA with mean values of 58-68% PUFA (Table 6). By
comparison, saturation profiles of crop contents of the lilac-crowned parrot were
more equivalent, and in the Cuban parrot MUFA and PUFA were found in similar
proportions of around 40% each (Table 6). Saturated FA SFA and MUFA were
found in similar proportions within the crop samples of each psittacine species,
41
41
except in the red-and-green macaw where concentration of SFA was double
MUFA, and in the Cuban parrot where SFA was half the concentration of MUFA
(Table 6). By comparison, crop contents of the kakapo had higher mean and
range values of SFA and MUFA concentrations, with far lower concentrations of
PUFA (12) compared to the five Neotropical psittacines (Table 6).
Crop samples fatty acid profiles of the scarlet macaw, the Cuban parrot
and the lilac-crowned parrot were within the range of values for hand-rearing
formulas (Figure 2). Hand-feeding formulas differed widely in saturation profiles,
but none of the products analyzed displayed a profile as low in MUFA as that of
the thick-billed parrot and the green-wing macaw (Figure 2). Compared with the
five Neotropical psittacine species analyzed, the diet of kakapo chicks (41)
presented a FA profile lower in PUFA and higher in SFA (Figure 2). The mean
concentration of PUFA for the kakapo (41) was also much lower than that in any
of the hand-feeding formulas (Figure 2). In general, most of the oils used in the
food industry (166) had FA profiles much lower in PUFA than that for free-living
psittacines or in hand-feeding formulas (Figure 2). Of these, only soy, corn and
cotton seed presented profiles within the range of that for free-living psittacines
and formulas (Figure 2). The main food plant species for the lear’s and hyacinth
macaw (130) also had FA profiles with far lower concentrations of PUFA and
higher concentrations of SFA than that for the other free-living psittacines and
the formulas (Figure 2).
Saturated fatty acids
Palmitic (C16:0) and stearic acid (C18:0) dominated the SFA from all
parrot species and from the hand-feeding formulas (Table 7). Palmitic acid was
the most common SFA in scarlet macaws (52% SFA), red-and-green macaws
(33%),Cuban parrot (52%), and in all the commercial formulas (41-79%) except
one (29%; Table 7). Stearic acid dominated the SFA from lilac-crowned parrots
(52%) and thick-billed parrot (69%; Table 7).
42
Table 5. Fatty acid (FA) profile, according to chain length, in crop contents from the five free-living psittacine species, the
kakapo (41), 15 commercial hand-feeding formulas (Chapter V), and the preferred food of adult free-ranging hyacinth
macaws (130). Profile data are presented as percentage of total fatty acid, mean ± standard deviation (minimum maximum).
Scarlet macaw (Ara macao), red-and-green macaw (Ara chloropterus), Abaco parrot (Amazona leucocephala bahamensis),
lilac-crowned parrot (Amazona finschi), thick-billed parrot (Rhynchopsitta pachyrhyncha), kakapo (Strigops habroptila). No
short-chain FA were found in any of the crop samples.
Scarlet
macaw
(n = 15)
Red-and-green
macaw
(n = 7)
Cuban parrot
(n = 5)
Lilac-crowned
amazon
(n = 6)
Thick-billed
parrot
(n = 2)
Kakapo
(n = 2)
Commercial
formulas
(n = 15)
Acuri and
Bocaiuva
Medium-
chain FA
1.37 ± 2.00
(0.00-5.64)
0.00 ± 0.00
0.13 ± 0.18
(0.00-0.39)
0.16 ± 0.15
(0.00-0.39)
0.00 ± 0.00
5.76 ± 1.90
(4.42-7.11)
2.68 ± 5.78
(0.00-18.3)
(29.6-
42.4)
Long-chain
FA
98.6 ± 1.99
(94.4-100)
99.9 ± 0.17
(99.6-100)
95.6 ± 1.60
(93.6-97.6)
99.6 ± 0.20
(99.4-99.9)
99.8 ± 0.27
(99.5-100)
94.2 ± 1.86
(92.9-95.5)
97.0 ± 5.71
(81.8-100)
(57.6-
70.4)
Very -long-
chain FA
0.08 ± 0.08
(0.00-0.23)
0.08 ± 0.14
(0.00-0.40)
4.28 ± 1.69
(2.12-5.95)
0.21 ± 0.08
(0.10-0.29)
0.02 ± 0.04
(0.00-0.07)
0.03 ± 0.04
(0.00-0.05)
0.32 ± 01.8
(0.00-0.81)
(0.00-
0.00)
43
Table 6. Fatty acid profiles by degree of saturation of crop content samples from five free-living psittacine species, the kakapo
(41), and the average of 15 commercial hand-feeding formulas (Chapter V). Data presented as percentage of total fatty acid,
mean ± standard deviation (minimum maximum). Scarlet macaw (Ara macao), red-and-green macaw (Ara chloropterus),
Cuban parrot (Amazona leucocephala bahamensis), lilac-crowned parrot (Amazona finschi), thick-billed parrot (Rhynchopsitta
pachyrhyncha), kakapo (Strigops habroptila).
Scarlet
macaw
(n = 15)
Red-and-
green macaw
(n = 7)
Cuban
parrot
(n = 5)
Lilac-crowned
amazon (n = 6)
Thick-billed
parrot (n = 2)
Kakapo
(n = 2)
Commercial
formulas
(n = 15)
SFA
21.1 ± 8.10
(11.6-35.0)
26.0 ± 7.03
(13.3-36.5)
20.2 ± 3.03
(16.8-23.2)
32.1 ± 9.22
(21.6-43.5)
17.8 ± 3.53
(15.7-21.8)
41.8 ± 1.10
(41.1-42.6)
21.5 ± 9.03
(10.4-41.2)
MUFA
20.6 ± 3.35
(14.2-27.3)
15.2 ± 10.8
(6.10-35.3)
39.9 ± 5.88
(30.4-45.9)
27.3 ± 10.4
(15.1-39.4)
13.8 ± 2.58
(11.0-16.1)
35.3 ± 0.56
(34.9-35.7)
28.2 ± 9.22
(19.9-50.8)
PUFA
58.3 ± 8.46
(42.9-71.0)
58.7 ± 13.3
(28.2-68.3)
38.6 ± 8.37
(29.8-50.7)
40.7 ± 9.22
(22.6-49.3)
68.3 ± 1.64
(66.7-70.0)
22.9 ± 0.54
(22.5-23.3)
45.6 ± 10.7
(31.6-68.9)
44
% MUFA
010 20 30 40 50 60 70 80 90 100
% PUFA
0
10
20
30
40
50
60
70
80
90
100
% SFA
0
10
20
30
40
50
60
70
80
90
100
1
2
3
4
5
6
7
8
9
10
11
Canola
1Soybean
2Palm
3Corn
4Cottonseed
5Sunflower
6Peanut
7Coconut
8Cod liver
9Olive
10 Safflower
11 Acuri palm seed
Bocaiuva palm seed
Licuri palm seed
Formulas
Scarlet macaw
Red-and-green macaw
Abaco parrot
Lilac-crown parrot
Thick-billed parrot
Kakapo
Fig. 2. Fatty acid profile of crop content samples of six psittacine species [this study and (41)], 15 commercial hand-feeding formulas, 11 different
commercially available oils (166), the palm fruits that constitute the main foods of the hyacinth and Lear’s macaws (130), and the average of three
maintenance poultry feeds (163-165). Data presented as percentage of total fatty acids. Scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus), Cuban parrot (Amazona leucocephala bahamensis), lilac-crowned parrot (Amazona finschi), thick-billed parrot (Rhynchopsitta
pachyrhyncha), kakapo (Strigops habroptila).
45
Table 7. Saturated fatty acid composition of crop content samples from the five studied free-living psittacine species, the
kakapo (41), the average of 15 commercial hand-feeding formulas (Chapter V), and the preferred food of the free-ranging
hyacinth macaw (130). Data presented as percentage of total fatty acid, mean ± standard deviation (minimum - maximum).
Scarlet macaw (Ara macao), red-and-green macaw (Ara chloropterus), Cuban parrot (Amazona leucocephala bahamensis),
lilac-crowned parrot (Amazona finschi), thick-billed parrot (Rhynchopsitta pachyrhyncha), kakapo (Strigops habroptila).
Scarlet macaw
(n =15)
Red-and-green
macaw (n = 7)
Cuban parrot
(n = 5)
Lilac-crowned
amazon (n = 6)
Thick-billed
parrot
(n = 2)
Kakapo
(n = 2)
Commercial
formulas
(n = 15)
C8:0
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
2.93 ± 0.05
(2.89-2.96)
0.00 ± 0.00
(0.00-0.00)
C10:0
0.02 ± 0.03
(0.00-0.10)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.01 ± 0.01
(0.00-0.04)
0.00 ± 0.00
(0.00-0.00)
0.90 ± 0.41
(0.61-1.19)
0.07 ± 0.27
(0.00-1.05)
C12:0
1.35 ± 1.99
(0.00-5.64)
0.00 ± 0.00
(0.00-0.00)
0.12 ± 0.18
(0.00-0.38)
0.16 ± 0.16
(0.00-0.39)
0.00 ± 0.00
(0.00-0.00)
1.94 ± 1.53
(0.86-3.02)
2.59 ± 5.63
(0.00-18.15)
C14:0
4.16 ± 5.13
(0.35-14.07)
0.76 ± 0.50
(0.00-1.45)
0.88 ± 0.11
(0.70-0.98)
0.25 ± 0.14
(0.13-0.52)
0.02 ± 0.03
(0.00-0.05)
0.87 ± 0.01
(0.86-0.88)
1.37 ± 2.42
(0.00-7.77)
C15:0
0.07 ± 0.17
(0.00-0.56)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.04 ± 0.9
(0.00-0.31)
46
Table 7. Continued.
Scarlet macaw
(n =15)
Red-and-green
macaw (n = 7)
Cuban parrot
(n = 5)
Lilac-crowned
amazon (n = 6)
Thick-billed
parrot (n = 2)
Kakapo
(n = 2)
Commercial
formulas
(n = 15)
C16:0
11.1 ± 4.26
(6.79-23.7)
11.1 ± 8.84
(5.42-32.2)
10.4 ± 0.96
(8.86-11.4)
12.1 ± 1.31
(9.92-13.8)
3.98 ± 0.51
(3.41-4.39)
29.8 ± 0.43
(29.5-30.1)
12.8 ± 3.23
(6.78-19.4)
C17:0
0.06 ± 0.04
(0.00-0.09)
0.04 ± 0.05
(0.00-0.12)
0.08 ± 0.09
(0.00-0.21)
0.10 ± 0.04
(0.04-0.16)
0.10 ± 0.09
(0.00-0.18)
0.38 ± 0.02
(0.36-0.39)
0.10 ± 0.18
(0.00-0.65)
C18:0
2.58 ± 1.05
(0.76-4.67)
6.50 ± 3.90
(1.63-13.25)
5.23 ± 2.10
(3.00-7.55)
16.8 ± 10.1
(4.63-30.6)
11.6 ± 3.38
(9.10-15.5)
4.27 ± 0.18
(4.14-4.40)
3.90 ± 1.72
(2.19-9.03)
C20:0
1.50 ± 1.21
(0.37-4.00)
7.31 ± 6.19
(0.38-18.14)
0.67 ± 0.29
(0.36-1.08)
2.03 ± 1.5
(0.58-4.37)
1.93 ± 0.23
(1.72-2.18)
0.51 ± 0.03
(0.49-0.53)
0.31 ± 0.09
(0.18-0.50)
C22:0
0.22 ± 0.20
(0.00-0.63)
0.25 ± 0.17
(0.00-0.44)
2.37 ± 1.13
(0.88-3.99)
0.48 ± 0.38
(0.14-1.19)
0.10 ± 0.08
(0.00-0.15)
0.21 ± 0.15
(0.10-0.31)
0.12 ± 0.21
(0.00-0.65)
C24:0
0.06 ± 0.07
(0.00-0.23)
0.06 ± 0.14
(0.00-0.40)
0.45 ± 0.19
(0.23-0.70)
0.21 ± 0.08
(0.10-0.29)
0.02 ± 0.04
(0.00-0.07)
0.03 ± 0.04
(0.00-0.05)
0.15 ± 0.20
(0.00-0.80)
47
Table 8. Monounsaturated fatty acid composition of crop content samples from the five studied free-living psittacine species,
the kakapo (41), and the average of 15 commercial hand-feeding formulas (Chapter V). Data presented as percentage of total
fatty acid, mean ± standard deviation (minimum maximum). Scarlet macaw (Ara macao), red-and-green macaw (Ara
chloropterus), Cuban parrot (Amazona leucocephala bahamensis), lilac-crowned parrot (Amazona finschi), thick-billed parrot
(Rhynchopsitta pachyrhyncha), kakapo (Strigops habroptila).
Scarlet
macaw
(n =15)
Red-and-
green macaw
(n = 7)
Cuban parrot
(n = 5)
Lilac-crowned
amazon (n =
6)
Thick-billed
parrot (n = 2)
Kakapo
(n = 2)
Commercial
formulas (n = 15)
C14:1n5
0.01 ± 0.03
(0.00-0.10)
0.00 ± 0.00
(0.00-0.00)
0.09 ± 0.13
(0.00-0.31)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.03 ± 0.10
(0.00-0.39)
C16:1
0.26 ± 0.16
(0.06-0.66)
0.25 ± 0.30
(0.09-0.98)
0.69 ± 0.20
(0.47-0.87)
0.46 ± 0.21
(0.26-0.83)
3.98 ± 0.51
(3.41-4.39)
0.33 ± 0.01
(0.32-0.34)
0.55 ± 0.55
(0.00-1.94)
C17:1
0.01 ± 0.02
(0.00-0.06)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
C18:1n9
13.0 ± 5.23
(6.09-25.8)
9.74 ± 9.26
(2.64-31.0)
24.7 ± 2.23
(23.0-28.5)
19.1 ± 9.79
(10.7-32.8)
8.25 ± 1.31
(7.07-9.67)
34.7 ± 0.56
(34.3-35.1)
30.0 ± 9.09
(19.2-49.7)
C18:1n7
1.84 ± 2.42
(0.00-9.68)
1.36 ±1.12
(0.54-3.80)
8.37 ± 3.76
(3.93-11.54)
7.20 ± 7.06
(1.13-20.63)
1.17 ± 0.58
(0.53-1.66)
0.00 ± 0.00
(0.00-0.00)
0.00 ± 0.00
(0.00-0.00)
48
Table 8. Continued.
Scarlet
macaw
(n =15)
Red-and-
green macaw
(n = 7) <