The improvement of post thawing quality of Bull Semen is a most current subject, Today. The presence of unsaturated fatty acids in the sperm membrane increases membrane fluidity and its resistance to ice crystals. In this study several levels of the oil containing combination o f polyunsaturated fatty acids omega- 3,6,9 was added to Bull semen diluents and about the fertility parameters ( Motility, Viability, Normal Morphology and …) were measured. In addition for the emulsification of oil in extender polyethylene glycol (PEG) was added as a more suitable solvent and was sonicated by ultrasonic system. Experimental groups included control and treatments A, B, C and D (sham and levels 1, 2.5 and 5% of omega- 3,6,9 fatty acids). In treatment A PEG was added alone to the diluents and in treatments B, C, D different concentration of omega-3,6,9 fatty acids in combination with PEG were added to extender based Tris- citrate buffer, egg yolk and glycerol. In this experiment 5 bulls used to semen ejaculation randomly. Semen collected by artificial vagina and its characteristics (Concentration, Motility, Viability and abnormality) were recorded. After dilution of semen samples were packed into 0.5 ml straws and then cooling and freezing process was performed. Samples were measured in term of Motility, Viability and normal morphology after 1 month. The results were evaluated by repeated measure ANOVA using SPSS and p<0.05 was considered significant. Motility and other dynamics parameters were analyzed by computer aided sperm analyzer (CASA) and Viability and normal morphology were measured by phase contrast microscope. Motility, Viability and normal morphology were 32.24, 10.38, 11.83, 9.71 and 8.02 %, 65.5, 17.5, 21.25, 15 and 15.67 %, 87, 77.75, 80, 78.25 and 78.67% for control, treatment A, B, C and D respectively. Our results showed that PEG has detrimental effects on Motility and Viability. In addition we found that combination of omega-3,6,9 fatty acids cannot be improve sperm motility and viability (p<0.05 ) after freezing and thawing. In conclusion this compound because of omega-6 and omega-9 fatty acids that have low double bond in their structure cannot be improve sperm membrane fluidity. In addition the use of lower percentage of PEG so that as the percentage of glycerol is replaced and also decreasing of levels of theses fatty acids can decrease detrimental effects were observed in this study.

Keywords