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Double-yolk eggs occur when ovulation occurs too rapidly, or when one yolk becomes joined with another yolk. These eggs may be the result of a young hen's productive cycle not yet being synchronized or ovulation is triggered by the hen laying the egg and two yolks are released at the same time to travel down the oviduct together, being surrounded by one shell and giving us the double yolker. They're occasionally laid by a heavy-breed hen, often as an inherited trait.
Double-yolk eggs occur when ovulation occurs too rapidly, or when one yolk becomes joined with another yolk. These eggs may be the result of a young hen's productive cycle not yet being synchronized or ovulation is triggered by the hen laying the egg and two yolks are released at the same time to travel down the oviduct together, being surrounded by one shell and giving us the double yolker. They're occasionally laid by a heavy-breed hen, often as an inherited trait.