Increasing the size of poultry

Hello everyone,

A few months ago I purchased a trio of Silver Grey Dorkings. Now all the poultry books mention them as a massive bird but as the Australian gene pool is closed, size is suffering and my birds are about average weight for a heavy breed although colour and most other traits seem to be correct. Egg weight is only average too.

How does one breed size without introducing new blood from another breed? Will selective breeding help here? I only intend to incubate and breed from 60gm+ eggs but am unsure if this is wise/necessary/useful.

Ginny
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