1. The Avian Egg Structure, Production, Function

2. Topics Anatomy of the Egg Anatomy of Avian Female Reproductive Tract
Process of Egg Formation
Aspects of Incubation and Hatching
Dystocias

3. Egg Types Eight Basic Shapes
Egg sizes range from 10 mm to 145 mm in length

4. Egg Colors
Multitude of colors, but all formed from two pigments derived from porphyrins
Color and mottling serves to camouflage the eggs in the nest
Cavity nesting birds have colorless eggs
Colors are added in the uterus during shell formation (below)

5. Anatomy of the Egg Seven Components
Yolk
Albumin
Membranes
Chelazia
Chorioallantoic Membrane
Air Cell
Shell

6. Anatomy of the Egg Seven Components
Yolk
Albumin
Membranes
Chelazia
Chorioallantoic Membrane
Air Cell
Shell

7. Yolk Formed in the liver, transported to ovarian follicle 33% lipid
19% protein
48% water
Layed in concentric layers

8. Albumin Four distinct layers Chalaziferous - inner thick
Inner thin layer
Outer thick layer
Outer thin layer
Protects yolk from invasion by microorganisms and provides water, protein and minerals to the embryo

9. Cross-section of Egg Shell
Membranes
Pores
Gas Exchange
Oxygen
Carbon Dioxide
15% weight loss during incubation
Related to incubation time (see tables)

10. Female Reproductive Tract
Ovary Most female birds have one functionally ovary (on the left)
Infundibulum - site of fertilization
Magnum - albumin addition
Isthmus - membranes
Uterus - shell gland
Vagina - transport to exterior
Sperm storage occurs at various sites in tract in some species

11. Cloacal Structure
Oviduct

12. Incubation Issues Temperature Humidity: regulates water loss Turning
Regulates rate of development
Tolerance for lowered temperature decreases as embryo grows
The incubation period (from laying to hatching) for budgie and cockatiel eggs is 18 to 21 days, respectively, whereas for the African grey parrots, Amazon parrots, and macaws it is app. 26 days
Humidity: regulates water loss
Determined by internal egg temp (humidity is 100%) and ambient humidity and gradient between the two
Turning

13. Incubation Times

14. Incubation Issues Turning Most critical from day 3 to day 7
Required for:
Proper incorporation of albumin into amnion
Failure to incorporate leads to water loss from albumin, increased viscosity and setttling between chorioallantoic membrane and inner shell membrane
This results in decreased oxygen diffusion
Ideal turning rate:
Minimum of 3x/d
More than 24x/d is not necessary

15. Managing Water Loss by the 14 -16 % Principle
Weigh egg at time of lay
Calculate projected weight at hatch by subtracting 15-18% of weight
Plot laid weight on day 1; and pip weight at appropriate point for incubation time (e.g. 21 days)
Connect with a straight line
Weigh eggs periodically during incubation

16. Altering Weight Loss Too much loss: Too little loss:
Place in incubator with higher humidity
Cover part of the egg with white glue
Too little loss:
Place in incubator with lower humidity
Thin part of the egg-shell by sandpapering

17. Appearance of Fertile Egg at Lay and during Early Development

18. Stages of Embryonic Development

19. Stages of Embryonic Development

20. Assessing Eggs during Incubation: Candling
Blood Vessels of Chorioallantoic layer
Embryonic Position

21. Assessing Eggs during Incubation: Candling
Blood Vessels of Chorioallantoic layer
Embryonic Position and Condition

22. Assessing Eggs during Incubation: Radiology
Embryonic Position and Condition
Note head down position

23. Hatching Process Membrane Drawdown - due to water-loss
Air Cell Formation - initiation of air-breathing by developing chick
Pipping
Rotation - counterclock-wise
Assisted Hatching - do not initiate until chorioallantoic blood vessels shut down.

24. Appearance of Healthy Chick at Hatch
Color
Hydration Status

25. Malpositions and Hatching Problems
Head at small end of egg is most common (mp2) - reduced hatchability
Head under left wing (mp 3) - lethal
Oversize Embryos
Unretracted Yolk Sacs

26. Malpositions and Hatching Problems
Unretracted Yolk Sacs
Idiopathic

27. Malpositions and Hatching Problems
Head at small end of egg is most common (mp2) - reduced hatchability
Head under left wing (mp 3) - lethal

28. Malpositions and Hatching Problems
Oversized Embryos

29. Dystocias (Egg-Binding) and Other Problems
Internal Laying