Effect of nano-hydroxyapatite on freezing ram spermatozoa

This experiment was designed to evaluate the protective effect of nano-hydroxyapatite against freezing damages on spermatozoa using five rams. Ejaculates (N=30) were collected with three-day intervals between sessions for six times. Ejaculates were pooled and split into 12 parts at each session. The amount of 0.01, 0.02, 0.05 or 0.1% nano-hydroxyapatite and 3, 5 or 7% glycerol were added. Samples were frozen and stored for two weeks. After that two straws from each treatment for each replication (totally 144 straws) were thawed and incubated at 37 ° C for 6 h. Sperm motility, viability, membrane integrity and acrosome integrity were evaluated at 0, 3 and 6 h after thawing. Results showed that there was no interaction between nano-hydroxyapatite, glycerol and incubation time (P>0.05). Sperm viability and acrosome integrity were not affected by different levels of nano-hydroxyapatite particles (P>0.05). There was no difference between the level of 0.01 and 0.1% nano-hydroxyapatite particles on the total (21.8 and 21.5%, respectively) and progressive sperm motility (17.8 and 17.7 %, respectively; P>0.05). Total and progressive sperm motility was the highest (24.8 and 21.0%, respectively) in the level of 0.02% nano-hydroxyapatite particles (P<0.05). Membrane integrity was higher in the level of 0.02% nano-hydroxyapatite particles (52.7%) than other levels (P<0.05). Therefore, the addition of 0.02% nano-hydroxyapatite particles to the ram semen extender improved the quality of frozen spermatozoa.