Effect of osmolarity and glycerol different levels in soybean lecithin-based extender on bovine sperm quality after cryopreservation

The effect of osmolarity and glycerol different levels in soybean lecithin-based extender on the bull sperm quality after cryopreservation was examined using six Holstein bulls in a 2 × 3 factorial trial based on completely randomized design, with three levels of osmolarity (250, 300 and 350 mOsml) and two levels of glycerol (5 and 7 %) .In general, semen samples were collected 36 times (from each bull, six times). After the initial evaluation of semen, samples were mixed together and assigned to each of treatments. After freezing and thawing process, parameters that were evaluated including; motion characteristics by CASA, viability, plasma membrane integrity and morphology. The results showed that frozen-thawed sperm in treatment of G7P300 had higher values than the other groups for total motility (69.50 %), progressive motility (48.89 %), lateral head displacement (3.69 µm/s), curvilinear velocity (168.80 µm/s) and straightness coefficient (61.89 %) (P≤0.05). In the treatments containing seven and five percent of glycerol and osmotic pressure of 350 mOsml, plasma membrane integrity (23.14 and 25.63 %, respectively) and sperm viability (58.70 and 64.60 %, respectively) were lower compared to other treatments (P≤0.05). But, in terms of morphology, G7P350 (92.34 %) and G5P350 (92.57 %) treatments were better than other treatments. The results of these experiment showed that the extender contained of seven percentage of glycerol with osmalarity of 300 or 250 mOsml was more efficient for cryopreservation of Holstein bull sperm.