Before the development of modern commercial meat breeds, broilers were mostly young male chickens culled from farm flocks. Pedigree breeding began around 1916.
Magazines for the poultry industry existed at this time. A hybrid variety of chicken was produced from a cross of a male of a naturally double-breasted Cornish strain and a female of a tall, large-boned strain of white Plymouth Rocks. This first attempt at a hybrid meat breed was introduced in the 1930s and became dominant in the 1960s. The original hybrid was plagued by problems of low fertility, slow growth and disease susceptibility.
Modern broilers have become very different from the Cornish/Rock hybrid. As an example, Donald Shaver (originally a breeder of egg-production-breeds) began gathering breeding stock for a broiler program in 1950. Besides the breeds normally favoured, Cornish Game, Plymouth Rock, New Hampshire, Langshans, Jersey Black Giant and Brahmas were included. A white feathered female line was purchased from Cobb. A full scale breeding program was commenced in 1958, with commercial shipments in Canada and the US in 1959 and in Europe in 1963.
As a second example, colour sexing broilers was proposed by Shaver in 1973. The genetics were based on the company’s breeding plan for egg-layers which had been developed in the mid-1960s. A difficulty facing the breeders of the colour-sexed broiler is that the chicken must be white-feathered by slaughter age. After 12 years, accurate colour sexing without compromising economic traits was achieved.