THE EFFECT OF OXYTOCIN, PROSTAGLANDIN Fac OR GNRH INJECTION ON FRESH AND FROZEN-THAWED SEMEN CHARACTERISTICS OF RAMS

摘要

The present study aimed to maximize the semen output from rams using oxytocin, prostaglandin p2a (PG p2a) or gondatrophin releasing hormone (GnRH) as well as to study the effects of these treatments on quality, freezability and antioxidant activity ofram semen. In the present work, 4 groups (each containing 3 Barki rams) were used as; control (group 1) injected with normal saline intramuscularly (i.m.) 30 min. prior to semen collection, group 2 injected with 10 i.u. oxytocin intravenously (i.v.) 10min. prior to semen collection, group3 injected with 250 ng of cloprostenol i.m. 30 min. before semen collection and group 4 injected with 50 |ig of gonadorelin i.v. 60 minutes before semen collection. Two ejaculates were collected from rams of all groups once weekly for 10 successive weeks. At the lst, 5th and l0th week semen samples were processesed for cryopreservation and testosterone and antioxidant enzymes were measured in the separated seminal plasma. Results indicated that both PG p2a and oxytocin resulted in significant (P < 0.05) increase in semen volume and total number of spermatozoa per ejaculates allover the experimental period without altering the quality of the fresh ejaculated or the frozen-thawed semen. Also, PG Fza and oxytocin had no undesirable effect on testosterone level and the values of total antioxidants, superoxide dismutase and glutathione peroxidase in seminal plasma. On the other hand, GnRH elevated the level of testosterone but did not increase the sperm output in rams.Conclusively, repeated injection of PGF2a and oxytocin prior to semen collection was found to be useliil when collecting ram semen for use in artificial insemination as they increase tlie sperm output without altering the quality of fresh or frozen-thawed semen as well as they have no deleterious effects on the antioxidant activities of seminal plasma and testosterone level in rams.