Cryopreservation of Iberian red deer (Cervus elaphus hispanicus) epididymal spermatozoa: effects of egg yolk, glycerol and cooling rate.
Two experiments were conducted to determine the effects of egg yolk (EY), glycerol, and cooling rate on the cryosurvival of red deer epididymal spermatozoa. The aim of Experiment 1 was to examine the effects of two EY types (clarified EY, CE, prepared by centrifugation, and whole EY, WE), and four EY concentrations (0, 5, 10 and 20%) on cryosurvival of red deer epididymal spermatozoa. Sperm samples were diluted to a final sperm concentration of approximately 200 x 10(6)spermatozoa/ml with a Tris-citrate-fructose-EY extender (TCF) prior to freezing. Sperm cryosurvival was judged in vitro by microscopic assessments of individual sperm motility, viability and of plasma membrane (by means of the HOS test) and acrosome (NAR) integrities. Cryopreservation of red deer epididymal spermatozoa frozen in a clarified EY extender, and with a 20% EY resulted in more vigorous post-thaw and post-incubation motilities (P<0.0001). Moreover, our results showed that regardless of the egg yolk concentration tested, the best sperm quality was obtained with the use of CE. Therefore, the objective of Experiment 2 was to explore the post-thaw effects of four clarified egg yolk concentrations (0, 5, 10 and 20%), two final glycerol concentrations (3 and 6%), and two cooling rates from 22 to 5 degrees C (slow: 0.23 degrees C/min; rapid: 4.2 degrees C/min) on red deer epididymal spermatozoa. At thawing, the effects of CE and glycerol concentrations, and cooling rate, all independently affected post-thaw sperm quality, while there were no effects of interactions on post-thawing sperm quality. Therefore, we studied each variable separately. Differences (P<0.05) for most of the semen parameters evaluated were found between the two final glycerol concentrations tested, with the high values after thawing found with the use of 6% glycerol (58.8+/-1.4 versus 46.2+/-1.4, for sperm motility). Moreover, the cooling rate did not have an effect on the semen characteristics, except for NAR (P<0.05), with the high values after thawing found with the use of the rapid protocol (64.5+/-1.4 versus 59.9+/-1.4). In conclusion, the use of 20% CE and 6% glycerol in combination with a rapid cooling rate, significantly improved red deer epididymal spermatozoa freezability.
Fernández-Santos MR
，Esteso MC
，Montoro V
，Soler AJ
，Garde JJ
... -
《THERIOGENOLOGY》
A pilot study on post-thawing quality of Iberian red deer spermatozoa (epididymal and electroejaculated) depending on glycerol concentration and extender osmolality.
The optimization of cryopreservation extenders is a fundamental issue for adequately performing germplasm banking on wild species. We have tested two glycerol concentrations (4 and 8%), and three extender osmolalities (320, 380 and 430 mOsm/kg; before adding cryoprotectants), for cryopreservation of epididymal and ejaculated sperm samples from Iberian red deer. All the extenders were based on Tes-Tris and fructose (for osmolality adjustment), and complemented with 20% egg yolk. Epididymal and ejaculated sperm samples were obtained from the cauda epididymis (post-mortem) and using electroejaculation, respectively. Samples were diluted 1:1 with each extender and equilibrated for 2 h at 5 degrees C. Then, they were diluted down to 100x10(6) sperm/mL and frozen at -20 degrees C/min. Post-thawed samples were assessed for motility (CASA), HOS test, proportion of swollen (osmotically challenged) cells in the untreated sample, viability and acrosomal status. For epididymal samples, 8% glycerol rendered a slightly higher proportion of intact acrosomes on viable spermatozoa than 4%; regarding extender osmolality, 380 and 430 mOsm/kg rendered higher motility results, and the 430 mOsm/kg yielded the lowest proportion of swollen spermatozoa. For ejaculated samples, 4% glycerol yielded more viable spermatozoa than 8%; for extender osmolality, 320 mOsm/kg rendered the highest percentages of progressively motile and viable spermatozoa, although 380 mOsm/kg extender was not significantly different. These results show that sample source influences extender suitability, and that extenders should be isoosmotic or rather slightly hyperosmotic. Future studies should test multiple glycerol concentrations and extender osmolalities in order to adjust them to these kinds of sample.
Martínez-Pastor F
，Martínez F
，García-Macías V
，Esteso MC
，Anel E
，Fernández-Santos MR
，Soler AJ
，de Paz P
，Garde J
，Anel L
... -
《THERIOGENOLOGY》
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