This document provides an overview of the 4-H embryology program. It discusses how fertile eggs are incubated to hatch chicks, the various parts of an egg and their functions, the incubator process over 21 days including candling and turning eggs, and caring for hatched chicks in a brooder with food and water. The goal is to teach participants about reproduction and chick development through hands-on incubation and hatching.

1. 4-H Embryology
An Overview
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2. Let’s begin with eggs.
EACH YEAR IN THE U.S. COMMERCIAL
LAYING HENS PRODUCE BILLIONS OF
TABLE EGGS FOR US TO EAT
BECAUSE THEY ARE VERY NUTRITIOUS
…HOWEVER…
IN NATURE
THE EGG IS NOT FOR EATING
IT IS FOR REPRODUCTION
AND
ONLY FERTILE EGGS WILL HATCH

3. • Fertile eggs come from special farms called
breeder farms where roosters and hens live together
and these eggs are incubated to produce chicks.
•The eggs you buy at the grocery store are grown at
“hen only” farms and they are not fertile so they will
not hatch when they are incubated.
Let’s begin with eggs.

4. How does an egg work?
THE EGG HAS MANY PARTS AND
EACH PART HAS AN IMPORTANT FUNCTION
DURING CHICK DEVELOPMENT
…FOR INSTANCE…
THE SHELL PROVIDES
PROTECTION
GASEOUS EXCHANGE
(O2 ENTERS AND CO2 LEAVES)
CALCIUM FOR BONES
THE YOLK PROVIDES
PROTEIN
FAT (FOR ENERGY)
VITAMINS AND MINERALS
YOLK
THE ALBUMEN PROVIDES
PROTEIN
VITAMINS AND MINERALS
THE CHALAZA
KEEPS THE YOLK IN
THE CENTER OF THE EGG
THE GERMINAL DISC
IS WHERE FERTILIZATION
OCCURS AND THE
CHICK BEGINS DEVELOPING

5. • CLEAN FERTILE EGGS
WILL BE PLACED IN
THE INCUBATOR
Startup day!
• MAKE SURE THE INCUBATOR
IS FUNCTIONING PROPERLY
AND READY FOR THE EGGS

6. • provides and maintains a favorable environment
for hatching fertile eggs.
• replaces the hen.
• must function properly and should be checked
daily.
An incubator…..

7. Important factors to successful
incubation are:
• Temperature
– Between 98-103º F
• Ventilation
– Clean fresh air must flow through the incubator
• Turning the eggs
– Eggs must be turned carefully 3 times each day.
Some incubators have an automatic egg turner.
• Humidity (water)
– There must be moisture to keep the chick
developing normally and prevent dehydration.

8. • Candling is the process of looking inside of an egg
without cracking it to see if the chick is developing. A
bright light is used to “candle” the egg.
Candling eggs

9. • Notice the blood vessels. This is the embryo
growing and eventually it will be developing very
quickly and fill up the entire inside of the egg.
Candling Day 3

10. Notice that the entire embryo is growing bigger
and is developing all of its body systems.
Candling Day 7

11. • Most chicks hatch on day 21, but sometimes hatching
begins a day or two earlier or later depending on the
conditions during incubation such as temperature,
humidity, etc.
• Be patient when hatching begins because it may take
several hours for a chick to exit the shell.
• It is best not to help the chicks hatch
•The struggle to hatch is necessary
for survival.
Hatching time!

12. Hatching start to finish.

13. Chicks hatching and
drying in the
incubator.
Hatching

14. • Chicks stay in the incubator until they are dry and
fluffy.
• It may take several hours for the chicks to dry.
• Once they are dry, place them in the brooder.
• Teach them to drink water by placing each chick’s beak
in the water source and then place them next to the feed
source so they will find it quickly.
The chicks have hatched,
now what ???

15. • A pen for chicks that provides protection, heat, feed
and water and space to move around.
• Absorbent bedding material is required so the
chicks can walk on it and scratch in it. Wood shavings,
paper towels, shredded newspaper work great!
• A heat lamp provides the chicks light and warmth.
What is a brooder?

16. • A pre-mixed commercial chick starter. This may be
purchased at a local feed store. Pet stores usually do not
sell this type of feed. Grit is not necessary at this age.
• DO NOT feed “scratch feed” or ground corn because
the chicks require more protein, vitamins and minerals
than are in these feeds.
What should the chicks be fed ?

17. • Change out daily
–Bedding
–Water
–Food
Keep your brooder CLEAN!!

18. Happy Hatching!

19. Connelly, R., Mores, C. & Simonne, A. (2009). What are the risks
of contracting diseases associated with chickens? (EDIS ENY-
724). Gainesville. University of Florida: Entomology and
Nematology Dept.
DeCubellis, C. (2007). Care of baby chicks (EDIS AN-170).
Gainesville. University of Florida: Animal Science Dept.
National 4-H Curriculum (2008). Hatching Classroom Projects:
Helper’s guide beginner grades 2-5 (BU-07595). Washington, DC:
National 4-H Council.
National 4-H Curriculum (2001). Experiments in poultry science:
Helper’s guide advanced grades 6-8 (BU-07596). Washington, DC:
National 4-H Council.
References

20. 4-H Embryology Working Group Team Members
Andy Toelle, Extension Agent Duval County
Lori Wiggins, 4-H Agent Taylor County
Chris DeCubellis, 4-H Agent Gilchrest County
Dr Sandra Tenbroeck, Associate Professor, Animal Science
Dr Richard Miles, Professor, Animal Science
This program was made possible by a
University of Florida Enhancement Grant