Background:The conservation of Bali bulls, the Indonesian native breed of cattle, is crucial for cattle breeding in Indonesia. To guarantee the spread of Bali bulls through artificial insemination the quality of the frozen semen must be high. To this end, using an extender material in addition to semen increasing spermatozoa's survival during cryopreservation is important. Green tea extract (GTE) can be used as cryoprotectant because its high antioxidant activity can help avoid reactive oxygen species formation.Methods: Semen of five Bali bulls from the National Artificial Insemination Center at Singosari, Indonesia was collected routinely twice a week. First, fresh semen inspection was performed to determine the feasibility of using Bali bulls as animal samples. The extender used in this study was Tris-based egg yolk. The divided samples into four treatments: T0 (no GTE added to the extender), T1 (0.05 mg GTE plus 100 mL extender), T2 (0.10 mg GTE plus 100 mL extender), and T3 (0.15 mg GTE plus 100 mL extender). The semen freezing process was conducted according to standard procedures and sperm quality parameters, i.e., sperm motility, viability, abnormalities, and membrane integrity observed pre-freezing and postthawing.Results: There were significant differences in total motility, progressive motility, viability, and integrity membrane of Bali bull sperm at both pre-freezing and post-thawing after adding GTE into the extender. In contrast, there were no differences in abnormalities among treatments. Conclusion:Adding GTE at a 0.15 mg into 100 mL Tris-based egg yolk extender can improve the quality of cryopreserved Bali bull sperm.

This study aimed to determine the effect of adding 96% ethanol extract of green tea (Camellia sinensis) in egg yolk tris diluter on the quality of spermatozoa of Bali cattle (Bos sondaicus) after freezing. The samples were divided into four different treatment groups, which contained semen sample + 13% glycerol + each egg yolk tris diluter + green tea extract (P0) 0 mg/100 ml, (P1) 0,05 mg/100 ml, ( P2) 0,10 mg/100 ml, and (P3) 0,15 mg/100 ml. The variables observed included motility, viability, and spermatozoa abnormalities. Data were analyzed using OneWay ANOVA and continued with Duncan's test (p<0,05). The results showed that the P3 group had motility of 49,00 ± 2,15, viability of 61,92 ± 1,70, and abnormality of 4,24 ± 2,16 significantly compared to the other groups. In conclusion, the P3 group with the addition of 0,15 mg/100 ml of green tea could increase the motility, viability, and abnormal spermatozoa of Bali cattle.