How does the longevity of Industrial strain Leghorns often compare to heritage strain Leghorns?

Industrial strains often have a shorter average lifespan due to intensive breeding for production

The expected lifespan of a Leghorn, often cited between five and seven years, is heavily influenced by the specific strain of bird acquired. Industrial strains have been selectively bred almost exclusively for maximizing rapid and high-volume egg output, a focus that often compromises overall systemic hardiness. This intensive push for production can predispose these birds to various internal health problems, including conditions like organ failure and reproductive cancers, which consequently shortens their average lifespan below the general estimate. In contrast, heritage strains are bred closer to the original ancestral stock, emphasizing sustainability and longevity. While heritage birds might lay slightly fewer eggs, their robust constitution allows them to maintain good production well into their fourth or fifth year, offering a longer-lived flock.