1. Session 12:
Avian and
Snake
Nutrition

2. Feeding Pet
Birds

3. Types of Birds
Psittacine Breeds Passerine Breeds
Natural seed eaters Seasonal migratory birds
Parakeets
Budgies
Cockatoo
Macaw
Parrots
Lovebirds
Canaries
Wrens
Swallows
Warblers
Blackbirds
Crows

4. Digestive Physiology of Birds
Differences in beak
shape and size
reflect
adaptations to
dietary sources of
food

5. Stomach divided into
distinct sections to
compensate for lack of
teeth and smaller
amounts of saliva
 Crop – used for wetting
food and temporary
storage
Mouth
Crop
Gizzard
Intestine
Ceca
Cloaca
Cloacal aperture
Esophagus
Digestive Physiology of Birds
Proventriculus

6. Digestive Physiology of Birds
 Proventriculus (aka “true
stomach”) – where gastric
acids and enzymes begin
chemical digestion
 Gizzard (aka “ventriculus”)
– strong muscular organ
used to grind feed into
smaller particles
Mouth
Crop
Proventriculus
Gizzard
Intestine
Ceca
Cloaca
Cloacal aperture
Esophagus

7.  Intestine & Ceca – sites of
nutrient absorption. Cecum
is very small (or non-
existent in some) so high
fiber diets are out!
 Cloaca – where urinary and
digestive tract reunite.
Urinary and fecal matter are
mixed & excreted together
Mouth
Crop
Proventriculus
Gizzard
Intestine
Ceca
Cloaca
Cloacal aperture
Esophagus
Digestive Physiology of Birds

8. Digestive Transit Time
Definition: Time from the ingestion of food to
the time when the undigested food is excreted.
Birds must have a constant supply of food. Some
birds can be in a state of starvation within
three days!
Digestive Transit Times by Species
Dairy Cattle: 24-72 hours
Humans: 18-24 hours
Dogs and Cats: 12-18 hours
Caged Birds: <12 hours
Budgies & Finches: 3-6 hours

9. Of Special Note in Avian Digestion
Faster metabolism
Must have “animal” vitamin D3, cholcalciferol
Require Proline and Glysine
Need increased amounts of sulfur amino acids
Extremely low urine volume; concentrated urine
Most do not utilize fiber

10. Avian Nutrition
 Feed them based on their digestive tract
 Example
Owls
- Can’t drink based on the shape of their
beak
- Can’t handle glucose
Lorikeets
- can’t handle protein

11. Faunivores
 Carnivores and Piscivores
- Adaptated to eating high protein diet with
a certain amount of fat
- Cold water fish contain about 30% fat
- Carnivores don’t utilize all of the prey,
they eat the mouse, digest as much as
possible and then regurgitate the bones
and hair ( owl pellets)

12. Insectivores
 Can’t digest the entire insect
- Some utilize the exoskeleton and some
penetrate the exoskeleton and digest the
inside of the insect only
- When they eat the entire insect, they get
all nutrients except Ca, which must be
supplemented
- High protein requirement 50-75%
- Insects high in protein and fat, low in Ca

13. Composition of Insects
 Depends on species and stage of life cycle
 Adult insects high in protein ( 50-75%) and
lipid ( 5-35%) with low level of
carbohydrates
 Good source of vitamins, trace minerals
and phosphorus, low in Calcium
 Chitinous exoskeleton has a negative
effect on digestibility

14. Florivores, Omnivores,
Herbivores
Florivores
- nectovores, frugivores, garnivores
Omnivores
- Most of our pet birds
Herbivores
- Ratites
- Combination of enzymes and microbes
- Can be fore gut or hind gut fermenters

15. Precocial vs altricial birds
 Precocial
- Eat on own when hatched
- Chickens, geese, ducks
- Large yolk in egg with lots of nutients
• Altricial
- pigeon- crop milk
- Hatchling dependent on parent for food
- Eagles, owls, most of our pet birds

16. Seeding of the GI tract with
microbes in young chicks
 Precocial chicks ingest the feces of adult
birds and feeds
 Altricial receive the bacteria when fed by
the adult ( regurgitated feed)
 “Cloacal drinking” vent “sucks” bacteria in
from the environment
 Retrograde urine, especially in ratites

17. Precocial chicks
 Neonates have down, actively forage for
their own food
 Their digestive tract is immature when
they hatch and takes up to 3 weeks to
mature

18. Altricial chicks
 Usually naked and helpless
 Parents must bring food to the chick and
actively feed it
 Digestive tract is well developed at hatch
 Milk production ( pigeons fed crop milk for
2 weeks)
- Crop milk nutritionally balanced, protein
and fat
- Prolactin stimulates crop milk production

19. Nutritional Problems
 Obesity- many pet birds and birds
confined in zoos and sanctuaries
 Leg abnormalities
- confinement, improper diet, high growth
rates, vitamin D, Ca, P, Mn, Zn, niacin or
biotin deficiencies
• Pendulous crop
- Due to yeast overgrowth

20. Avian Feeding Management
 Birds tend to pick out certain seeds in mixes;
therefore don’t eat balanced diet
 Should leave entire amount of food there until
bird has eaten it all
 Grass seeds (corn, oats, barley, etc) are too low
in calcium; Sunflower, safflower seeds are too
high in fat.
 Best to feed a complete commercial feeding mix
or pellets

21. Essential Nutrients & Ingredients in
Avian Diets
Grit:
made from ground minerals and sand; key in helping bird
grind up foodstuffs; stays in the gizzard
Who needs grit?
Birds that ingest whole seeds – helps with shells
Birds that remove seeds don’t really need grit
How to feed grit:
1/8 to ½ teaspoon every 2 years. Over ingestion of
grit causes intestinal impaction

22.  Vitamin A:
 Promotes skin and mucous membrane health
 Feed high Vit A foods: carrot tops, broccoli, sweet
potatoes
 Vitamin D (Cholcalciferol)
 Important in bone development
 Feed high calcium foods – almonds, cereals, cheese,
yogurt, oyster shells
Essential Nutrients & Ingredients in
Avian Diets

23. What Budgies Eat
 Prone to renal disease if fed 100%
pelleted diet long term
 Feed percentage of pellets, millet,
sprouted seeds
 Safe “human” foods: cooked pasta,
brown rice, legumes, veggies, fruit,
bread
Source: Oklahoma State
University

24. What Cockatiels Eat
 Pellets
 Cereal & grain sources:
 Cheerios, Chex, Total
 Dry or cooked pasta, corn, oatmeal
 Popcorn, crackers
 Meaty, dark green, orange & yellow veggies
 High Vit A content: beets, broccoli, carrots.
 NO lettuce, green peppers, zucchini, spinach!
 Protein sources:
 legumes, tofu, small pieces of cooked lean meat

25. What Macaws Eat
(Blue & Gold)
 ½ cup pellets with ½ cup fresh
fruits and veggies (wash well!)
 Seeds can be offered as treats
(sunflower)
 Protein sources: cooked sweet
potato, yogurt
 Fresh water at all times

26. What Parrots Eat
 Commercial pellets for 60-80% of diet;
Seeds less than 12% of diet
 Table food:
 Mostly leafy green veggies, tomato, beets, peas,
carrots
 Unsweetened cereal; bread
 Small amounts of protein: cooked eggs, boiled
chicken, well done chicken bones
 Limit seeds; leave shells on for parrot’s activity

27. What Canaries Eat
 “Black and White” seed mix: 70%
canary seed & 30% seeds from the
rape seed plant; can use canary
pellets
 Very delicate, will dehydrate in short
time; fresh water always!
 Mineral grit and cuttlebone should be
added
 Sunflower seeds as a treat. Soak
them overnight to help bird break
them down
Source: University of Maryland

28. Chickens- layers that produce
eggs, primarily Leghorn
 Starter feed- nutritional deficiencies and
imbalances may impair growth and future egg
laying, contain antibiotics and coccidiostats
 Grower- 6 weeks to sexual maturity
approximately 21 weeks
 Developer- can be inserted between grower
and layer diet to increase production
 Layer diet is fed free choice with large
amounts of calcium for egg shell

29. Phase Feeding for Laying
Chickens
Layer phase 1
-Birds are still growing and increasing in
production, feed formulation is at maximum
density
-Onset of egg production until past the time
of maximum egg mass output

30. Phase 2
Layer phase 2
-High but declining egg production and
increasing egg weight
-Egg production declines to about 65 percent
of maximum

31. Phase 3
Layer phase 3
-Egg production continues to decline below
65 percent of maximum while egg weight
decreases only slightly
There is no evidence that nutrient
requirements of layers change during the
period of lay

32. Molting
 Layers are sometimes molted to extend
the production period
 Feed and light are restricted during the
molt
 Can also encourage a molt by nutrient
excess or deficiency
 Molt can last 3-6 weeks
 After molt laying resumes

33. Broilers
 Eggs hatch in 21 days
 Starter diet is similar to layer diet but
more energy dense as broilers grow faster
 At 3 weeks, broilers are switched to a
lower nutrient density for the next 3-6
weeks
 At 7 weeks the finisher diet begins. This
diet is lower in nutrients and fed until
market weight is reached

34. Reptiles

35. Nutrition of Boas and Pythons
 General Nutrition
 Snakes consume whole prey, which makes a balanced
diet easy
 Balanced Diet
 Pet snakes usually fed “pinkies”
 In the wild, snakes eat mammals
birds, other reptiles, fish, worms
amphibians and bugs

36. Nutrition of Boas and Pythons
 Graduate from pinkies to mice to rats
to some rabbits
 Try not to feed the snake food that
is bigger than its midsection
 Don’t handle snake after it’s eaten –
it may regurgitate
 Careful when snake is shedding – it
can be aggressive

37. Nutrition of Boas and Pythons
 Never feed live prey – can result in
bite wounds
 Teaching a snake to eat dead rodents:
 1. Jiggle it by the tail and a hungry
snake will eat
 2. Don’t use your fingers to dangle
the prey – snakebites hurt

38. Nutrition of Boas and Pythons
 Feeding Frequency:
 Juveniles: feed appropriately sized prey every
6-7 days
 Adults: Feed every 7-14 days
 Keep log of eating and defecation to monitor
snake’s needs and potential illnesses

39. Nutrition of Boas and Pythons
 Ball Pythons
 Shy feeders who do best with a hide box for
shelter
 If reluctant to eat, try feeding at night since
they’re nocturnal
 Imported Ball Pythons may not recognize
classic white mouse as prey, so use brown
mouse, gerbil or hamster

40. Nutrition of Boas and Pythons
 Water
 Fresh water available at all times
 Provide a bowl or tub for them to submerge
themselves in for soaking
 Temperature is important
 80-95°F degrees for ball pythons

41. Iguanas
 Cold blooded
- Increase body temperature for optimum
digestion
- Sunbathe for 4 hours
- Forage for food after 4 hours of
warming/digestion
- High protein requirement
- Feeding dog food or cat food can lead to
gout due to uric acid accumulation

42. Iguana ( cont)
 High fiber diets prevent many digestive
problems
 Vitamin deficiency can lead to pathologic
fractures when iguanas are fed diets
deficient in Ca and P
 Utilize vitamin D3 like birds

43. Anole Nutrition
 Insectivores so diet should consist mostly
of insects
 Feeder insects should be fed a high quality
diet prior to being fed to the anole, this is
called “gut loading” of insects ( there are
many of these foods on the market)
 Crickets, meal worms, houseflies, fruit
flies, and silkworm

44. Anole ( con’t)
 Also benefit from fruit nectar
 Dietary supplements including vitamins D-3
and mineral calcium will also be a benefit
 Watering can be difficult as anoles in the
wild drink dew and rainwater droplets so
they will not utilize a bowl of water
 It is recommend to mist the terrarium
daily to provide the anole with drinking
water

45. Turtles and Tortoises
 All in the group of chelonians
 All posses a shell
 Tortoise are generally terrestrial
( however we refer to box turtles and
wood turtles)
 Turtle generally refers to water turtles
 Correctly feeding them begins with
identifying what type of chelonian you have

46. Land Tortoises
 African Spur-thighed, Leopard, Star, Red-
footed and Yellow-footed are examples
 Should be placed outside in warm weather
to graze, exercise and bask
 ( they like to dig, so bury an 8 inch barrier
to prevent escape)
 Provide sun and shade in enclosure
 Remove any toxic plants and foreign
material

47. Sunshine
 Vital for turtles and tortoises for
synthesis of vitamin D
 If unable to provide an outdoor enclosure,
provide a full spectrum flourescent light
12 inches or less above the turtle or
tortoise
 They are unable to absorb Vit D through a
window

48. Tortoise Diet
 95% vegetables
 Majority of vegetables should be dark,
green, leafy like collard, mustard, radish,
turnip, kale, cabbage, dandelions, bok choy,
broccoli leaves, clover, legumes, cut grass
and weeds from yard ( no pesticides)
 Small amounts of spinach, swiss chard,
beet greens, frozen veggies

49. Tortoise diet ( cont)
 Hibiscus flowers and leaves, grape leaves,
carnations, roses, and squash flowers are
favorites
 Alfalfa pellets can be soaked and offered
 Fruits are well accepted but mineral poor
and incorrect Ca/P ratio
 Fruits can form 5% of diet melons, grapes,
apples, oranges, peaches, strawberries,
raspberries, bananas with peel etc

50. Tortoise diet ( cont)
 Red and yellow footed can eat more fruit,
up to 20 %
 Commercial tortoise diets can be soaked an
used as a small portion of the diet
 Chop entire daily diet of veggies, fruits
and commercial diet together to avoid
picking and choosing
 If you don’t use turtle chow, add Ca
supplement daily, vit. Supplement weekly

51. Offering food/water
 Hatchling turtles and tortoises should be
fed daily
 Adults can be fed every other day or
three times a week
 Fresh clean water to drink in and soak in
 First year of life is very important since
they are growing rapidly, it is vital they
receive a balanced diet to prevent bone
and shell problems

52. Box Turtles
 Fed a diet very different from tortoises
 Young box turtles will eat primarily animal
material such as earthworms, slugs, snails,
beetles, millipedes, spiders, crayfish and
grasshoppers
 Chopped up pinky mice can also be used for
juveniles
 Commercial turtle chow can be offered in
limited amounts

53. Box Turtle adults
 Will eat plant material including
mushrooms, tomatoes, strawberries,
raspberries, and other fruits
 Should eat about 50% animal protein and
50% plants ( 75% veggies and 25% fruit)
 Utilized the fruits and veggies list for
tortoises

54. Finicky Box Turtles
 Build the diet around a commercially
prepared box turtle chow and add animal
and plant material
 They need lots of beta carotene ( a
precursor of Vit A) in the diet to prevent
medical problems

55. Aquatic Turtles
 Red eared sliders, painted turtles, mud and
musk turtles, soft shell turtles, snapping
turtles
 All require clean warm water for swimming
 Eat most of their meals in the water ( try
to have a separate water dish for eating to
prevent fouling of swimming water)
 Allow an area where turtle can exit the
water to bask

56. Aquatic Turtle diets
 Feed a variety of foods
 Commercial floating food sticks as a
portion of the diet
 Small turtles should be offered chopped
earthworms, snails, slugs, shrimp in the
shells, chopped up whole fish ( from frozen
to kill parasites), chopped mice and gut-
loaded insects
 Raw chicken, lean beef, liver and gizzards
limited

57. Aquatic turtles ( cont)
 As water turtles get older, they will
usually consume dark green leafy
vegetables, ( see tortoise list)
 Older turtles may also consume duckweed,
anarchis, algae and some fruits, also offer
floating food sticks

58. Diets too high in protein and
other nutrients
 Shell abnormalities will result
 Fed exclusively primate chow, dog food or
cat food will usually develop grossly
deformed shells, especially the top shell
( the carapace)
 Shell may also become domed and
misshapen
 Obese animals have fat bulging from
armpits and groin impeding locomotion

59. Temperature requirements for
turtles and tortoises
 Correct temperature range for efficient
digestion
 In addition to poor digestion, they are
prone to many diseases
 Hibernation is recommended for turtles
and tortoises that hibernate in the wild
who are in good physical condition ( consult
a vet familiar with hibernating these
species)

60. Iguana Nutrition
 Vegetarians specifically foliovores
 Foliovores consume primarily leaves in
their natural environment
 Hindgut fermenters which require
microbes to assist in their digestion ( like
cows)
 Requires a high body temperature which is
why iguanas will bask for about 4 hours in
the morning before foraging for food

61. Iguanas in the wild
 Eat leaves, fruit, flowers of selected
herbs, shrubs, trees and vines
 Dietary diversity does not occur on a daily
basis
 They tend to consume less common plants
and seasonally available foods

62. Iguanas ( cont)
 Young iguanas are foliovores just like the
adults
 All iguanas can develop a taste for
inappropriate food items: popcorn, cheese,
dog food
 Monkey biscuits contain too much D3 which
can cause mineralization of internal organs
which will cause death
 Dog food can lead to gout in iguanas

63. Appropriate diet size iguanas
 Hatchlings up to 14 inches finely chopped
food twice a day
 Older iguanas up to 3 feet in length can be
fed medium chopped food once daily
 Adults over 2 ½ years of age or over 3 ft
in length fed coarsely chopped food every
other day
 All foods thoroughly washed, chopped and
mixed

64. Composition of the Iguana
 Baby iguanas are growing rapidly, incorrect
diets can lead to deformed, ill animals
 A high percentage of the diet dark-green
leafy vegetables
 80-90% of the diet should consist of two
from this list: collard greens, turnip
greens, mustard greens, bok choy, swiss
chard, clover, red or green cabbage, water
cress, savoy, dandelions, parsley, alfalfa
pellets

65. Composition ( cont)
 Beet greens an spinach contain oxalates
that may bind dietary calcium should only
be offered occassionally
 Kale, brussels sprout, broccoli, cabbage,
and cauliflower can bind iodine leading to
goiter so they should also be limited
 The darker outside leaves are more
nutritious

66. Composition ( cont)
 10-15 % of diet from frozen mixed
veggies, squash, sprouts, carrots, cooked
sweet potato, cucumber, okra, parsnips,
asparagus, mushrooms, green and red
peppers, peas, beans, corn and green beans
 Backyard weeds and grasses as forage
 Fruits can make up the rest of the diet,
they are mineral poor so they are used for
flavor

67. Acceptable fruits for Iguanas
 Papaya, mango, apple, peach, pear, plum,
strawberry, banana with the skin,
raspberry, melon, tomato, grape, raisins,
star fruit, kiwi, blueberry and guava
 Figs are high in calcium
 Show grain breads or bran cereals can be
offered sparingly or prepared iguana food
can be fed
 Light green lettuce can be offered as a
treat

68. Treats
 Hibiscus leaves and flowers, rose petals,
geranium flowers, carnations and
dandelions
 Live food is not necessary but some enjoy
crickets, meal worms and pinky mice. These
should be fed sparingly because they are
poor dietary items for this species

69. Feeding continued
 Avoid food preferences by providing 10
different food items in the daily diet and
mix them thoroughly to prevent selection
of preferred ingredients
 Food items should have a positive calcium
to phosphorus ratio
 Most water is obtained from the diet so
feed juicy, moist food

70. Feeding cont
 Offer a large pan of water for soaking
 Most iguanas relieve themselves in the
water so this will also help keep the
enclosure clean
 Provide a well balanced diet and only
supplement if recommended by your
veterinarian. Oversupplementation can be
detrimental to the iguana.

71. Bearded dragons
 Omnivores, eating a mixture of
invertebrates, vertebrates ( insects and
small animals) and plant material
 In captivity: feed a combination of insects
( mostly crickets) greens and vegetables

72. Insects for Bearded dragons
 Bearded dragons are prone to impactions
of their digestive tract and the chitinous
exoskeletons of insect can cause problems
 Mealworms can cause impactions so feed
them in very limited quantities and avoid
them in juveniles
 Feed insects that have recently molted so
the exoskeleton is soft

73. Insects ( cont)
 Crickets should be no larger than the
space between the dragons eyes
 Adult dragons can be fed waxworms,
silkworms, butterworms, red worms,
earthworms, and newly molted mealworms
and superworms as treats. Crickets should
provide the bulk of the diet. You can
occassionally offer a pinky mouse.

74. Juvenile Bearded Dragons
 Should be fed insects more often than
adults
 Feed at least twice a day, the amount they
will eat in 10 minutes
 Heat is necessary for digestion so make
sure it is appropriate
 Greens and vegetables can be available at
all times

75. Insects for Bearded dragons
 All insects should be gut loaded ( fed
nutritious food that is then passed to the
lizard) and lightly dusted with a calcium
and Vit D supplement
 Dust with a complete multivitamin no more
than once a week
 Do not feed fireflies or boxelder bugs as
they are believed to be toxic to bearded
dragons

76. Greens and Vegetables should
make up 20-30% of diet
 Mixture of green leafy vegetables ex
dandelion greens, collard greens, chickory
greens, mustard greens, turnip greens, and
parsley
 Other vegetables; squash, carrots, green
beans, peas, bell peppers
 Some fruits: berries, apples, grapes,
cantaloupes, papaya, mango, blueberries
and bananas

77. Commercial Diets
 Should only be used as a supplement or
mixed in with the diet
 Long term effects of commercial diets
have not been determined