Abstract The objective of the study was to investigate the effects of zinc sulphate additive to semen extender on sperm parameters after cryopreservation. The spermatozoa of five Farahani rams breed (with a mean age of 3.05 years and weight of 60 ± 5 kg) were taken twice a week. The semen was collected from the rams by artificial vagina and then the samples were mixed to removing the individual effects of each ram. The sperm samples (in five replicates) were divided randomly to four groups (zero, 50, 100 and 150 micromoles of zinc sulfate), which each falcon was added to the desired diluent and mixed with Zn and tris and prepared for freezing steps. Sperm samples were evaluated after thawing for sperm morphology by Hancock test. Results showed that there was significant difference in the sperm morphology the level of 150 μl Zn sulfate indicated a significant decrease compared to the control group (P0.05). Therefore, the use of zinc sulfate in ram semen extender might be improving sperm morphology after the freezing-thawing.
