A power control device for automatically and proportionately metering power to a heating device used to create a warm microenvironment conducive to the health and growth of an animal during a predetermined incubation period is herein disclosed. The power control device transmits proportionally more power to a heating device where an ambient temperature measured outside of the microenvironment is nearer a predetermined lower limit, and proportionately less power when the ambient room temperature measured outside of the microenvironment is nearer a predetermined upper limit.