The ISA brown is a breed of domestic hybrid chicken that is thought to have been developed by crossing Rhode Island Red and Rhode Island White chickens, although the modern type contains genes from many other breeds. It is not a true breed, but a hybrid that was developed by breeding unrelated dams and sires until the desired result was produced. The name “ISA” is an acronym that stands for Institut de Sélection Animale, which is the institute where the breed was initially developed in 1978.
The ISA brown was developed for egg laying purposes, but has recently become a popular pet due to its friendliness when young and its low maintenance nature. However, when placed with other breeds, it can become aggressive. Despite their popularity as egg layers, hens typically produce fewer eggs after their second or third seasons, which make them more suitable for backyard environments. This breed can be bred with other breeds, but these crosses do not produce actual ISA chickens. Despite this, they are often good layers and cocks tend to produce good meat.
Image Caption: Free range ISA Brown hens at CERES Community Environment Park. The hen in the foreground has no white in ruff or tail and may be a different breed. Credit: Pengo/Wikipedia (CC BY-SA 3.0)