Improvement in quality and storage ability of rabbit semen by using black or thyme seed as dietary supplementation.

The quality of incubated or chilled rabbit semen is quickly lowered with time due to high-rate production of reactive oxygen species (ROS). Black seed (BS) and thyme (THY) are rich sources of natural antioxidants, which may be able to control ROS production and improve semen quality for use in artificial insemination. In this study, V-line rabbit bucks, seven months old, were fed diets supplemented with 50 or 100 g of BS or THY for 60 days. Semen was collected twice weekly. The quality of fresh sperm was measured, and diluted sperm was incubated for up to 12 h. Chilled, diluted sperm, stored at 4℃ for up to 3 days, was evaluated. The results indicated that BS and THY increased rabbit libido, decreased abnormal sperm and non-viable sperm percentages and significantly lowered total bacteria counts of diluted sperm. In conclusion, bucks fed a diet supplemented with BS or THY had enhanced semen quality and storage life, because of the antioxidant properties of BS and THY. The best incubation results were obtained with the THY100 treatment, whereas the best-chilled results were obtained with the BS100 group.