Green Tea Extract in the Extender Improved the Post-Thawed Semen Quality and Decreased Amino Acid Mutation of Kacang Buck Sperm

SIMPLE SUMMARY: The Kacang goat (Capra hircus) is a livestock species native to Indonesia, and its genetic resources must be protected and preserved to prevent extinction. Frozen semen is the appropriate choice for artificial insemination in Kacang goats. Post-thawed semen can be used more than 20 years after semen collection and can cover a large area of acceptors. However, frozen semen of the Kacang buck is currently unavailable. This was the first study involving the mutation of the amino acids as a quality parameter of post-thawed Kacang buck semen. The results showed that post-thawed Kacang buck semen that was frozen in a 0.10 mg green tea extract per 100 mL skim milk–egg yolk extender and that was equilibrated for one hour resulted in the highest semen quality and lowest amino acids mutation. Glycine, valine, leucine, serine, and asparagine strongly correlate to post-thawed sperm motility. It can be concluded that antioxidants helped improve the quality of post-thawed Kacang buck semen. This finding can be used by the Artificial Insemination Center in Indonesia to produce Kacang buck frozen semen for artificial insemination, which can then be massively applied in the field to increase the population and genetic quality of Kacang goats in time to prevent risk of extinction. ABSTRACT: This study was the first to combine the addition of antioxidants to a skim milk–egg yolk (SM–EY) extender and different equilibration periods to obtain higher quality post-thawed Kacang buck semen. This study aimed to determine the effects of green tea extract (GTE) on the quality of frozen Kacang goat sperm equilibrated for one and two hours. The pool of Kacang buck ejaculate was equally divided into four portions and was diluted in an SM–EY extender that contained four doses of 0, 0.05, 0.10, and 0.15 mg of GTE/100 mL for T0, T1, T2, and T3 groups, respectively. The aliquots were treated for an equilibration period of 1–2 h before further processing as frozen semen. Post-thawed semen quality was evaluated for sperm quality. The Sanger method was used for DNA sequencing, and the amino acid sequence was read using MEGA v.7.0. The post-thawed semen of the T2 group that was equilibrated for one hour had the highest semen quality. Pre-freezing motility had the highest determination coefficient compared to post-thawed sperm motility. This study is the first to report amino acid mutation due to freeze–thawing. The frequency of amino acid mutations revealed that T2 was the least mutated amino acid. Glycine, valine, leucine, serine, and asparagine strongly correlated to post-thawed sperm motility. It can be concluded that a combination of 0.1 mg GTE/100 mL extender as an antioxidant and one-hour equilibration period resulted in the best post-thawed Kacang buck semen quality.