Incubation and Embryology of the Chicken Flashcards
What does the nucleus look like?
A small, white or light-colored speck.
How big is the nucleus?
About the size of a pin head (2-3 mm diameter).
Where is the nucleus located?
Top side of the yolk.
What does the male sperm cell find before fertilization?
The lodgment.
What is a fertilized egg characterized by?
A white ring on the yolk surface.
How large is the ring on a fertilized egg?
3-4 mm in size.
What temperature should fertile eggs be stored at?
54-59 F.
*Should maintain a constant weight.
What do temperatures above 77 F cause?
Cellular replication of the germ cell on the yolk of the fertile egg, increasing embryonic mortality and reducing hatchability.
What do temperatures below 50 F cause?
Inactivation of the germ cell.
What humidity should fertile eggs be stored at?
75%.
When storing fertile eggs, which side should be facing downward?
The small end.
When is optimal hatchability achieved in eggs?
When they are less than 10 days old.
When is reasonable hatchability obtainable in eggs?
Up to 14 days of age.
What are the 4 principles of artificial incubation of fertile eggs?
- Correct and even temperature controlled by a thermometer or thermocouple.
- Correct humidity controlled by ventilation rate and water application.
- Turning of the fertile egg approximately 90 degrees several times per day (manual or automatic).
- Correct O2 and CO2 concentrations controlled by ventilation.
What temperature is required for incubation?
99-102 F w/ a +/- 2 variation before significant embryonic mortality.
At what 2 stages are embryos most susceptible to temperature variation?
- Early phase.
- Late phase.
What is placed on the eggs to aid in maintaining humidity?
Water via water sprayers.
What is the humidity range that embryos can survive in?
40%-90%, below or above this range is when negative consequences occur.
What humidity is good hatchability achieved at?
50-65%.
*Three days before hatching, this increases to 70-90% humidity.
Why is egg rotation/turning done?
- To ensure that the developing embryo on the yolk does not adhere to the shell membrane.
- To allow the embryo to slide in the inner white and access additional nutrients for embryonic development.
When does adherence to the shell membrane occur?
- During fertile egg storage.
- During early incubation (first week).
Why is it better to rotate/turn the egg an uneven number of times?
So that the egg is not in the same position for an extended period of time.
What concentration of CO2 is optimal for chick growth?
0.4%.
Above what concentration is CO2 detrimental to chick growth?
1%.
What are the concentrations of O2 and CO2 in a normal atmosphere?
- 21%.
- 0.04%.
When is ventilation rate and CO2 concentration most critical for chicks?
Late phase of incubation.
*Implied by hatched chicks being susceptible to O2 deviation.
When is the earliest eggs can be candled?
5-8 days of incubation.
*At 18 days to see line between embryo and air cell.
Why are eggs candled?
To examine the embryo for blood vessel development and a dark spot.
What does an infertile egg look like when candled?
It is clear and there is no evidence of blood.
What does early embryonic death look like when the egg is candled?
A blood ring surrounding the yolk.