Effects of Ultraviolet Light Supplementation on Pekin Duck Production, Behavior, and Welfare

SIMPLE SUMMARY: Ducks, like other poultry species, have the ability to see in the ultraviolet (UV) portion of the light spectrum; however, very little research has explored how UV lighting affects Pekin duck welfare. Therefore, the objective of this study was to determine how providing supplementary UV light in a UV-deficient environment could affect production parameters and behavior. Pekin ducks were reared under either light-emitting diode (LED) bulbs with supplemental UV light (UV) or just LED bulbs (control). The results from this study indicate that Pekin ducks reared under UV light have both lower acute and chronic stress susceptibility and lower fear responses. It was also found that eye morphology can be manipulated with UV light exposure. There were no treatment differences in production parameters such as growth, feed efficiency, tibial mineral composition, visual gait score, or stride length. The results of this study demonstrate the necessity of UV light exposure in duck growout settings and emphasize the need for correct artificial lighting in the poultry industry. ABSTRACT: Ducks, like other domestic poultry species, can visualize the ultraviolet (UV) portion of the light spectrum; however, the importance of UV light radiation in artificially lit duck growout facilities remains unknown. The objective of this study was to determine the effects of UV light supplementation on Pekin duck production parameters, eye development, stress, and fear. Pekin ducks were reared with light-emitting diode (LED) lights supplemented with UV light or just LED lights (control). There were no differences in body weight (p = 0.32), feed conversion ratio (p = 0.38), or gait score (p = 0.89). Differences in eye morphology were observed, with ducks reared under UV light having narrower (12.3 ± 0.06632 mm; p = 0.010) and lighter (1.46 ± 0.01826 g; p = 0.025) eyes than the control (12.5 ± 0.05583 mm; 1.53 ± 0.02386 g). Ducks reared in UV environments had lower acute and chronic stress susceptibility with lower plasma corticosterone (6317 ± 593.79 pg/mL; p = 0.024), heterophil to lymphocyte ratios (0.43 ± 0.02889; p = 0.035), and composite asymmetry (0.58 ± 0.0298; p = 0.002) than control ducks (9242 ± 1120.7 pg/mL; 0.54 ± 0.04212; 0.76 ± 0.03726 mm, respectively). Ultraviolet ducks had a faster latency for the first head movement during tonic immobility (61.28 ± 9.4863 s, p = 0.026) and required more attempts to induce tonic immobility (1.71 ± 0.07333, p = 0.018) than control ducks (100.7 ± 14.846 s and 1.48 ± 0.06478, respectively). There were no differences in inversion testing (p = 0.91). These results indicate that UV lighting can lower stress and fear responses in Pekin ducks and can therefore increase welfare. Additionally, this study emphasizes the importance of choosing correct artificial lighting for all poultry species.