Depreciation. More capital expense spread over fewer dozens with the same equipment useful life.
Labor. Same labor to care for fewer birds
Return on invested capital. I spend x to get return y. Now I get fewer dozens on the same x and my profit per dozen must increase to get the same y.
Do you run any EC facility? Does the market appear to be accepting the cost?
What does it break down to per dozen? Sorry, you probably already put that in somewhere here... getting old.