In terms of sexing day old chicks broiler breeding companies would traditionally sell a feather sexable female parent product so that the broilers could be sexed at hatch by feather typing. Many processors no longer raise their broilers sex separately, but it is still a common practice in Asia and South America.
The existing broiler breeders continue to sell slow-feathering female parents suitable for feather sexing at hatch, but Cobb’s main product is a fast-feathering female parent because there are production advantages for growers that do not sex their broilers. It is more economical to grow the sexes separately and process the females at a younger age than the males. Slow-feathering is a sex-linked trait and can be used to sex chicks at hatch by feather type. The C line was the slow-feathering line that usually had more broiler characteristics and the D line was usually fast-feathering and was better for egg production. Slow-feathering is dominant and sex-linked so that the female parent product was slow-feathering and needed to be vent sexed to differentiate the by-product males from the female product. The A and B sire lines are fast-feathering, and when the slow-feathering CxD hybrid female was crossed to the fast-feathering male, fast-feathering female and slow-feathering male broilers were produced. The broiler industry calls this trait slow-feathering, but in the literature it is usually referred to as late-feathering and early-feathering.