EFFECTS OF SEMEN EXTENDER SUPPLEMENTED WITH L-METHIONINE AND PACKAGING METHODS (STRAWS AND PELLETS) ON POST-THAW GOLDFISH (Carassius auratus) SPERM QUALITY AND DNA DAMAGE

BACKGROUND: Amino acids protect spermatozoa against cell damage during cryopreservation due to have antioxidant property and found in seminal plasma at high concentration. OBJECTIVE: The aim of the present work was to analyse the effect of extender supplementation with L-methionine on post-thawed sperm motility, duration and DNA damage and also it was tested the feasibility of using straws and pellets method for the cryopreservation of goldfish (Carassius auratus) sperm. MATERIALS AND METHODS: Extenders were supplemented with different L-methionine concentrations of 1 mM; 1.5 mM; 3 mM; 6 mM. Semen samples diluted at the ratio of 1:9 by the extenders were subjected to cryopreservation. After dilution the semen was aspirated into 0.25 ml straws and 0.1 ml pellets, the straws and pellets were placed on the tray, frozen in nitrogen vapor and plunged into liquid nitrogen. DNA damage was determined with comet assay after cryopreservation.. RESULTS: Our results indicated that an increase in the concentration of L-methionine caused a significant increase in the motility rate and duration of sperm in goldfish (C. auratus) (p<0.05). In addition, duration and percentage of motility in pellets were higher than in straws. Comparing all concentrations of L-methionine, the best concentration of L-methionine was 1.5 mM. Highest post-thaw motility (45.00 +/- 7.07%) and duration of motility (17.00 +/- 0.71s) were obtained with the extender at concentration 1.5 mM in pellets. Addition of the extender with L-methionine was reduced DNA damage compared to control group. CONCLUSION: Consequently, pellets could be use for goldfish sperm cryopreservation and the tested amino acid affected the motility parameters, and semen extenders could be supplement with L-methionine.