Resumen de Efecto de la edad del donante y de la aplicación de implantes de melatonina en la crioconservación espermática ovina
W. García, Abigail Tabarez Rojas, S. Osuagwuh, M.J. Palomo
The effect of age and melatonin implant on sperm cryosurvival of eight rams during two consecutive springs was studied. In the first spring, the rams (18 months old) were divided into two groups; group A with melatonin implants (Melovine®) inserted 60 days before semen collection, and group B without melatonin implants. Semen was collected via artificial vagina and according to the experimental design, fresh ejaculates were immediately mixed, centrifuged twice at 600g for 10min, re-suspended in a Tris-based extender containing 15% powdered egg yolk and 5% glycerol, and refrigerated for 4 hours at 5°C before freezing in liquid nitrogen vapour. The experiment was repeated with the same animals (30 months old) in the next spring. Sperm cryosurvival (mean±SEM, n=6) determined with eosin-nigrosin stain showed no significant difference after thawing between group A (35.73±6.37) and group B (40.96±6.14) in the first spring. When rams were 30 months old, post-thaw viability in group B (41.50±4.24) was higher than in group A (31.17±3.71), but not significantly (p>0.05). Total motility was significantly higher (P<0.001) in frozen sperm of older males irrespective of melatonin. Results from post-thawed sperm morphometry by computer-assisted system (ISAS®) showed no difference between the groups but varied significantly (P<0.001) with age.
