Effect of temperature and cell concentration on dolphin (Tursiops truncatus) spermatozoa quality evaluated at different days of refrigeration

Characterization of Bottlenose Dolphin (Tursiops truncatus) Sperm Based on Morphometric Traits

“…Our results showed that the principal piece length was greater at 5 °C than at 15 °C. This suggests that sperm velocity would be better at 5 °C, as suggested by previous studies that found that higher sperm motility resulted from lower temperatures [ 60 , 72 ]. Therefore, refrigeration could be an interesting alternative to cryopreservation in order to avoid morphometric alterations and to maintain high levels of motility and viability, and to ensure the good morphology of bottlenose dolphin sperm [ 72 ].…”

“…In bottlenose dolphin, differences in testosterone levels depending on the season have been reported [ 71 ]. The high quality of ejaculated dolphin sperm [ 16 , 72 ], together with the existence of sperm subpopulations (based on morphometry and variations according to the testosterone levels) may be adaptations for sperm competition and linked to the mating system of this species. However, the potential links between testosterone and sperm traits, including morphometry, are not clear, although a relationship between testosterone levels and normal spermatozoa has been observed in other species [ 73 ].…”

“…This is consistent with previous studies in several species, in which a long-term conservation process, such as cryopreservation, decreased the dimension of the spermatozoa head [ 50 , 85 , 86 ]. Likewise, it is known that the sperm cooling process, including cryopreservation, affects acrosome membranes [ 87 , 88 ], which could explain the reductions observed in head dimensions; however, the acrosome integrity in chilled dolphin sperm is well conserved during the storage period [ 72 ]. Therefore, another plausible hypothesis could be the association of sperm morphometry with DNA integrity.…”

“…As mentioned above, the midpiece is characterized by the presence of mitochondria, which provide energy to spermatozoa, improving their swimming velocity [ 16 , 70 ] and increasing longevity [ 92 ]. A previous study described a decrease in dolphin sperm motility with time [ 72 ]. Thus, since midpiece length is associated with sperm motility, a decrease in this morphometric parameter is to be expected.…”

Status of Sperm Functionality Assessment in Wildlife Species: From Fish to Primates

“…Ruiz-Diaz cooled dolphin sperm to 5 °C instead of freezing it, and the sperm still showed a high degree of viability and swimming capacity when maintained in Beltsville Thawing Solution and measured by CASA. Maintaining sperm at 5 °C (refrigeration) instead of freezing provides an alternative storage method, on the condition that the sperm are used within 5 to 7 days [ 59 ], an approach similar to that used in the boar industry.…”