Egg-laying chicken breeds tend to fall into two categories: heritage and hybrid. Heritage-breed chickens have been around since your grandparents’ time and often have multipurpose qualities, while hybrid chickens are commercially developed for a specific purpose. Some layers have both a heritage strain and a variety that has been commercially bred for production — not necessarily hybrid, but commercialized — so be sure to ask your source which you’re getting if this distinction matters to you.
Heritage Chickens
“[Heritage] breeds were carefully selected and bred over time to develop traits that made them well-adapted to the local environment, and they thrived under farming practices and cultural conditions that are very different from those found in modern agriculture”, according to The Livestock Conservancy, a nonprofit that works to protect livestock and poultry breeds from extinction. The organization defines heritage chickens as those that are American Poultry Association standard breeds, meaning their parent and grandparent stock breeds were recognized by the APA prior to the mid-20th century and meet the APA Standard of Perfection guidelines; are naturally mating; have long, productive outdoor lifespans — breeding hens should be productive for five to seven years and roosters for three to five years; and have a slow growth rate, reaching appropriate market weight for the breed in no less than 16 weeks.