Effect of Age and Postmortem Time on Some White-Tailed Deer (Odocoileus virginianus texanus) Epididymal Sperm Characteristics and Response of Cryopreservation

Problem statement: Males rather than females of the White-Tailed deer (Odocoileus virginianus texanus) are more susceptible to hunting because their physical characteristics, therefore their elimination can increase a genetic degradation and a lower productivity because of the effect of gender. Thus, the aim of the current study was to evaluate the effect of age and postmortem time of White-Tailed deer on its epididymal-tail sperm motility and morphology and the response to sperm cryopreservation. Approach: Twenty two hunted deer were used and were classified into three age-groups: A = 1.5-3.5; B = 4.5-5.5 and C = 6.5-7.5 years old and four groups according to postmortem time: 1= 0-3; 2 = >3-5; 3 = >5-7 and 4 = > 7 h. Two samples per animal (one per each epididymal) were diluted and frozen with Triladyl® and Tris-Fructose. Thawing was done 72 h post freezing. Results: Age did not neither affect motility nor morphology (p>0.05). Postmortem time had a deleterious effect on motility (p<0.05), a significant drop in this trait was found after 5 h postmortem (58.1, 56.1, 37.5 and 38.3% motility in groups 1-4, respectively). However, did not affect morphology until 7 h postmortem and after 7 h an unexpected, significant (p<0.05) improvement was found (66.4, 74.9, 62.2 and 83.8% of normal sperm in groups 1-4. As regarding freezing ability, though without a statistical difference (p>0.05), the percentage of samples with acceptable motility after freezing and thawing was greater with Tris-Fructose than with Triladyl (36 Vs 18%). Conclusion: It was concluded that these results indicate that age as studied does not affect epididymal sperm quality in this species, while post-mortem time has a detrimental effect on motility and epididymal sperm can be successfully cryopreserved, for which Tris-Fructose would be better as an extender than Triladyl.