Feed quality, quantity, and type certainly played a roll. Poultry on the family farm was emphasized more and more later. The availability of grain benefited the birds. In particular corn, where before they were often left to scratch for scraps that the more "important" livestock left behind. Scientific advancement's in livestock nutrition was evolving fast. Our birds eat better now than they ever have in history. The birds in the 1880s could only wish that their owners could debate the best feeds, and feed methods online as we do.