Spent Layers
‘Spent layers’ or old hens are egg-laying birds that are past their prime and whose output is increasingly irregular, rendering them economically inefficient. The cost of feed and inputs remains the same but their earning capacity is greatly reduced. In the intensive egg industry, which is all about efficiency and return, these hens are often given off for sale to a thriving old layer market in Nigeria.

The level of egg production, egg size, and shell quality decrease each year. Most commercial layers are kept for 2-3 years as their egg production decreases after this time.
Benefits of Purchasing Well-Fed Old Layers
These are:

They are sold at comparatively cheaper prices than other mature birds.
Healthy and strong old layers have been inspected and well scrutinized for deformities and infections.