A method is disclosed which is useful for elevating blood thyroid hormone levels in avian species (especially poultry species such as chickens, turkeys, ducks, quail, etc.) by implantation, injection, or supplementation of feed or water with thyroid hormones or thyroid-active substances (e.g., L-thyroxine, triiodothyronine, defatted and dessicated thyroid) to induce molting in order to extend egg production.