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

## TL;DR

This study shows that red LED light improves reproductive hormone levels in donkeys during the non-breeding season.

## Contribution

The novel finding is that red light exposure increases key reproductive hormones in donkeys.

## Key findings

- Red LED light elevated testosterone, Activin A, LH, FSH, and AMH levels in donkeys.
- Red light also increased melatonin concentrations during the non-breeding season.
- Red light exposure was more effective than blue or white light in improving hormone profiles.

## Abstract

The donkey industry is one of the most vibrant animal farming industries in China. A lot of research is being conducted to improve various aspects, including reproduction. As a seasonal breeder, seasonality in breeding is a hurdle to achieving optimized production, including higher pregnancy rates and foal production. In recent years, researchers adopted various techniques to improve conception rates in Jennies, including estrus synchronization and inhibin immunization. The current study aimed to investigate the impact of various monochromatic light sources, i.e., red, blue, and white light on plasma hormones of Dezhou jennies during the non-breeding season (November–February). Our results showed that red light improves reproductive efficiency in jennies.

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.