Blood Ring on Candling — What It Indicates

Correct Answer: Early embryonic death

A blood ring seen during candling is a ring of blood visible just inside the shell, indicating that the embryo started developing (blood vessels formed) but then died early. This is pathognomonic of early embryonic death.

What Causes Early Embryonic Death?

• Extreme temperatures in the incubator (too high or too low).
• Nutritional deficiencies in the breeder hen (especially Vit. A, B₂, E, Mn).
• Disease or infection in the breeder flock.

Candling Appearances Summary

• Infertile egg: Clear, transparent — no blood vessels, only yolk shadow.
• Blood ring: Ring of collapsed blood vessels → early embryonic death ✔
• Fertile, live egg (day 7): Spider-web of vessels; dark embryo spot.
• Dead-in-shell (day 18): Dark, opaque mass; no movement; embryo died late.
• Piped egg: Air cell has been broken by chick's beak; visible crack from inside.

Why Other Options Are Wrong

• Infertile egg → appears clear, not as a blood ring.
• Piped egg → is a late-stage event (day 21) visible externally; not seen as blood ring.
• Dead-in-shell → appears as dark opaque mass, not a ring of blood.