Methods for increasing breast muscle weight in poultry are disclosed herein. These methods can include delivery of compositions via in ovo administration. The methods disclosed herein also encompass the delivery of proteins such as delivery of Fibroblast Growth Factor-2 (FGF-2) or Insulin-like Growth Factor-1 (IGF-1). The methods disclosed herein are effective for increasing breast muscle weight in poultry, both in the embryo, and at slaughter age.
