By "weaned," what do you mean? When the hen quits calling her chicks over for tasty bugs but pecks them away instead?
I didn't notice any of mine eating less when this happened. When the hen called it quits on mothering, I separated her from her chicks and the chicks just kept eating their little heads off as usual.
I did graph the growth of this year's hen raised chicks, but unfortunately I can't find my data from last year when I raised a batch artificially and indoors. I wrote the information on our calendar, and another family member threw that away last January (darn).
My impression is that the hen raised chicks grew faster and feathered out more quickly, though.