Effect of Monochromatic Red, Blue, and White Light on Reproductive Hormones of Male Donkeys During the Non-Breeding Season

Red light suppresses melatonin and helps in improving reproductive efficiency in donkeys during the non-breeding season (November–February). In this study, the effects of red, blue, and white LED light were assessed. For this purpose, 40 adult Dezhou donkeys were divided into 4 groups, each receiving equal treatment for 40 days. All groups received 8 h of natural light. Additionally, the red group received 6 h of 50 lux of red LED light (468 nm) directed at a single eye. The blue group received 6 h of 50 lux of blue LED light (468 nm). The white group received 6 h of 50 lux of white LED light (468 nm), and the control group received only 8 h of natural sunlight. Blood samples were collected on the 21st, 28th, 34th, and 40th day of the experiment to analyze plasma hormone concentrations of progesterone (P4), Inhibin B (INH-B), Testosterone (T), Activin-A, Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), Antimullerian Hormone (AMH), and Melatonin. In conclusion, red LED light directed at one eye showed the most promising results, elevating plasma hormone concentrations of testosterone (T), Activin A, LH, FSH, AMH, and melatonin.