EFFECT OF ADDING GLUTAMIN AND METHIONINE TO SEMEN EXTENDER ON POST-CRYOPRESERVATION SEMEN QUALITY OF HOLSTEIN BULLS

This study was conducted at the Department of Artificial Insemination, Abu-Ghraib pertaining to the Department of Animal Resource Services/Ministry of Agriculture during the period from October 2012 to February 2013 to investigate the effect addition of glutamine and methionine to Holstein bull's semen extender on post freezing semen characteristics following different cryopreservation periods. Seven mature Holstein bulls of 2.5-3 years old were used in this study. Semen was collected by using an artificial vagina as one ejaculate / bull / week. The evaluations were performed for fresh semen, and thereafter, pooled, and subdivided to different experimental groups and diluted by using Tris-based extender. Glutamine (40 mM), methionine (2.5 mM) and control group to determine their effects on sperm individual motility, dead: alive sperm percentage, total sperm abnormalities percentage and normal acrosome percentage following different cryopreservation periods (cooling at 5 Celsius, 48 hours, one month, two months and three months post cryopreservation). Addition of Glutamine had positive significant (P<0.05) effect on sperm individual motility, 3 months post cryopreservation as compared with control and methionine groups. Addition of Glutamine increased (P<0.05) a live sperm percentage, 3 months post cryopreservation in comparison with the control and Methionine groups. On the other hand, addition of Glutamine decreased (P <0.05) total sperm abnormalities percentage as compared with control group throughout the whole period post cryopreservation. Glutamine and methionine were superior (P<0.05) than control group in high normal acrosome percentage during all preservation periods. In conclusion, addition of glutamine as primarily and methionine as secondarily to bulls semen extenders improved post cryopreservation semen characteristics through their pivotal role as antioxidant and cryoprotectant agents simultaneously. These will certainly increase sperm individual motility, a live sperm percentage, normal acrosome percentage and decrease total sperm abnormalities percentage, and may consequently enhance fertilization and pregnancy rates of inseminated cows.