I've heard a lot about the need for "young bees" to feed brood. It is known
that older bees can reverse the changes to their physiology and once again
produce brood food. 
     I was once doing 2 things in a small outyard. I was moving one hive and
requeening another. I kept the old queen in case of emergency. Many foragers
were returning to the site of the moved hive. I set a deep on a bottom-board
and gave them a few combs. Then I said, "what the heck " and gave them the
spare queen. They got along well and produced brood. They made a fine nuc
with 100% forager bees.

Dick Marron

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