Poultry color perception of artificial light-emitting diode (LED) lighting mediates bird physiology and behavior; however, very limited research has focused on how changes in LED light color affect these same parameters in Pekin ducks. Therefore, the objective of this investigation was to determine how four LED bulbs emitting various portions of the visible light spectrum - monochromatic blue (BLUE), monochromatic green (GREEN), monochromatic red (RED), and white (WHITE) - impact the stress, fear responses, eye development, and growth of 768 straight run Pekin ducks. Elevated plasma corticosterone concentration and heterophil to lymphocyte ratio was observed in BLUE and RED ducks compared to WHITE and GREEN ducks (P=0.005 and P=0.001, respectively), and asymmetry scores were highest in BLUE ducks (P < 0.001), indicating BLUE and RED lighting increase the stress susceptibility of Pekin ducks. Eye weight was lowest in BLUE and RED ducks compared to GREEN and WHITE ducks (P < 0.01). No differences were observed in d 35 body weight, FCR, gait score, or fear response parameters (P > 0.05). These results indicate BLUE and RED lighting may not be adequate for Pekin duck growout, and Pekin ducks may require artificial light sources containing a broad range of wavelengths, as seen with WHITE and GREEN lights, rather than lights containing more concentrated ranges such as in RED and BLUE lights, but further investigation is needed to understand how eye weight affects duck light perception and welfare. The current findings emphasize that although Pekin ducks and chickens are both sensitive to light color, species-specific nuances in light perception may cause distinct differences in Pekin duck versus broiler physiological responses and must be considered when selecting artificial light color in Pekin duck growout facilities.
