Within the past three decades, red meat and poultry scientists focused on developing strategies and technologies to manipulate muscle development during embryonic and fetal development. This area continues to be an area of focus because muscle fiber number is established during this time and determines the basis for all future growth. In poultry, numerous studies demonstrated in ovo feeding of growth factors, vitamins, or other nutrients improved chick embryonic muscle and intestinal development. Improving in ovo muscle development could benefit the poultry industry by possibly influencing meat yield, growth rate, or myopathy conditions. During the past five years, the Gonzalez Laboratory at the University of Georgia developed a nicotinamide riboside in ovo feeding methodology for broiler-chicken embryos, which altered muscle development. When injected into a developing embryo's yolk sac, nicotinamide riboside increased pectoralis major muscle weight and muscle fiber density at hatch. This protocol will demonstrate a methodology to accurately and reproducibly conduct in ovo feeding studies utilizing commercial standard- and high-yielding broiler embryos. These data and methods will allow other research groups to perform in ovo feeding studies with much success and reproducibility.