Chick Development: Step-by-Step Incubation Guide

🐣 Chicken Embryo Development Timeline (21 Days)

🥚 Day 1 (0–24 hours)

• Cell division begins soon after incubation temperature is reached.

• Primitive streak forms (this becomes the backbone).

• Head and eye areas start forming.

Candling: Nothing visible yet.

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🥚 Day 2

• Heart begins to form and starts beating (~42 hours).

• First blood vessels appear.

• Brain begins developing.

Candling: Still usually too early to see clearly.

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🥚 Day 3

• Blood vessel network expands.

• Eye becomes visible as a dark spot.

• Wing and leg buds begin forming.

Candling: Faint spider-like veins may be visible in strong light.

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🥚 Day 4

• Heart is beating strongly.

• Limb buds grow longer.

• Embryo begins slight movement.

• Tongue starts forming.

Candling: Clear veins visible; small dark embryo spot.

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🥚 Day 5

• Elbows and knees develop.

• Reproductive organs begin forming.

• Beak begins developing.

Candling: Larger dark center with more defined veins.

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🥚 Day 6

• Beak hardens slightly.

• Voluntary movement begins.

• Comb tissue starts forming.

Candling: Noticeable movement possible.

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🥚 Day 7

• Toes begin forming.

• Eyelids start developing.

• Comb more visible.

Candling Checkpoint:

Healthy egg shows:

• Strong vein network

• Distinct embryo mass

Clear egg = likely infertile.

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🥚 Day 8

• Feather follicles begin forming.

• Ear openings visible.

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🥚 Day 9

• Claws begin forming.

• Embryo looks more bird-like.

Candling: Large dark mass, active movement.

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🥚 Day 10

• Beak hardens.

• Toenails visible.

• Rapid growth stage.

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🥚 Day 11

• Tail feathers begin forming.

• Body feathers start emerging.

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🥚 Day 12

• Toes fully formed.

• Scales begin forming on legs.

• Down feathers developing.

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🥚 Day 13

• Skeleton begins hardening.

• Body covered in fine down.

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🥚 Day 14

• Embryo turns head toward blunt (air cell) end.

• Rapid size increase.

Candling Checkpoint:

Egg mostly dark; clear air cell visible.

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🥚 Day 15

• Gut drawn into body cavity.

• Feathers continue maturing.

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🥚 Day 16

• Scales and claws well developed.

• Chick occupies most of egg space.

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🥚 Day 17

• Beak turns toward air cell.

• Yolk sac shrinking as it’s absorbed.

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🥚 Day 18 (Lockdown Day)

• Stop turning eggs.

• Chick positions for hatch.

• Yolk sac mostly absorbed.

• Head tucked under right wing.

Candling: Almost completely dark except large air cell.

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🥚 Day 19

• Chick draws oxygen from air cell.

• Internal pip may occur (pierces air cell membrane).

You may hear faint peeping.

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🥚 Day 20

• External pip (small crack in shell).

• Chick rests between efforts.

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🐥 Day 21 – Hatch Day

• Chick “zips” around shell.

• Pushes top off and emerges.

• Wet and tired at first.

• Fluffs up within hours.

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❗ Important Notes

• Hatch may occur between Day 20–22.

• Do not assist unless absolutely necessary.

• Avoid opening incubator during Days 18–21 (humidity drop can shrink-wrap chicks).