Apparatus and associated methods involve a hangable LED light assembly constructed to provide a selected color output illumination as a function of excitation intensity. In an illustrative example, the color output may be selected to promote biological development throughout livestock development stages (e.g., incubation, growth, and reproduction). The light intensity may controllable, for example, in response to a light dimmer arranged to modulate AC excitation applied to the LED downlight. As the light intensity is decreased in response to a simple dimmer control, the spectral output of the LED downlight may shift its output wavelengths. Accordingly, some exemplary installations may provide controlled combinations of intensity and color to substantially optimize lighting conditions for livestock.