Abstract
The current study aimed to evaluate the impact of different antioxidants on the sperm quality-related parameters of frozen-thawed Brown Swiss bulls. Semen samples were collected from each bull once per week using an artificial vagina. The semen samples were pooled and divided into aliquots. One of them was diluted with a tris-based extender without any antioxidants and served as a control group. Other aliquots were diluted with a tris-based extender supplemented with 0.75% green tea extract, 0.25% strawberry extract, 1.5 mM of vitamin E, 2 mM of vitamin C, and 0.5 mM of caffeine at 37°C. The semen was evaluated for motility, viability, abnormality, plasma membrane integrity, and acrosome integrity immediately following the addition of diluent for the control group and again after one week of storage in liquid nitrogen at -196°C and re-thawing for all groups. The results revealed that green tea extract had the most beneficial impact on improving sperm parameters (motility, viability, abnormality, plasma membrane integrity, and acrosome integrity) followed by strawberry extract and vitamin E then vitamin C and caffeine as compared to the post-thawing control group. So, according to the results obtained, it was concluded that addition of green tea extract in the semen extender can enhance the quality of frozen-thawed bull sperm. However, given the price and availability of strawberry, we recommend using strawberry extract to boost seminal quality.

Key words: Antioxidants, Brown Swiss, Semen Cryopreservation, sperm parameters, semen quality, vitamins