In-vitro evaluation of ram sperm, frozen in tris-EGG yolk extender supplemented with methionine, cysteine and bht

The aim of this research is to study the effects and comparison of the antioxidants [2,5mM, 5mM methionine, 1mM, 2mM cysteine, 1mM, 2mM butylhyroxytoluene (BHT)] for semen parameters on freeze-thawed ram sperm that diluted in TRIS-citric acid and egg yolk (%20) sperm extender. Sperm was collected from five Kivircik rams twice a week with electro-ejaculator in breeding season and pooled. After pooling the mean of the volume (ml), motility (%), sperm number (x109/ml), plasma membrane integrity (HOST, %), acrosomal, other morphologic and total morphologic defects (%) was found 3,92, 84,0, 1,96, 93,8, 5,60, 0,4 ve 6,0 respectively. The diluted sperm samples were cooled to 5ºC within an hour and equlibrated for another two hours after adding %6 of glycerol. 200x106 sperm cells were placed into 0,25ml french straws and freezed with a programmable freezing device (-120 oC) and plunged into liquid nitrogen tanks until spermatological analyses. After thawing of the sperm straws, the motility, HOST also acrosomal, other morphologic and total morphologic defects parameters were investigated. All antioxidant added study groups were statistically different (P<0,05) from antioxidant-free control group in terms of motility and HOST parameters and also were in a positive correlation between these parameters (r=0,880). In terms of acrosomal defects, there was a statistical difference among control group with the 2,5mM, 5mM methionine and 1mM, 2mM cysteine groups (P<0,05). Also there was a difference between the doses of methionine and cysteine groups (P<0,05). The difference between 1mM cysteine and 2mM BHT groups was statistically significant (P<0,05). The statistical difference for the total morphologic defects was found among control group and 2mM cysteine, 2,5mM and 5mM methionine groups (P<0,05). The study had reached the conclusion that the effects of antioxidants that added to ram sperm diluents with different doses had protective effects on spermatological parameters. Key words: Ram sperm, cryopreservation, methionine, cysteine, BHT