I am only interested in egg production and wondered how someone knew which hatchery had the most productive line of barred rock hens. Does anyone know if any studies have been done on breeder stock of sex-linked birds? I would assume that many black sex link layers come from fairly productive barred rock hens and are crossed to a genetically positive traited RIR. But, I have never heard much about these parent stock. Is there a line of barred rock that say has Hendrix genetics or Hyline genes directly in line?