Customizing Semen Preservation Protocols for Individual Dogs and Individual Species: Sperm Preservation beyond the State of the Art

Abstract

Contents Sperm quality can be variable in morphometric and physiological attributes between males of different species, between males within species subtypes reared under different environmental conditions, between ejaculates of the same male or even between sperm populations within an ejaculate. Clinical semen evaluation is based on evaluation of whole ejaculates, which is not a chemically or physiologically well‐defined entity, rather a collection of heterogeneous subpopulations giving different measurements and possessing different fertilizing potential. Identification of subpopulations with different motility patterns is important as well as characterizing the subtle structural changes underlying the motility differences observed. The ability to identify populations of sperm responding rapidly or failing to progress through the capacitation process may have clinical applications. Studies of lipid‐phase fluidity of sperm membranes, mathematical modelling of membrane ion transport, role of modifying components and detergent‐resistant microdomains are of particular interest. When customizing extenders to ejaculates from cryosensitive males or species, a thorough knowledge of species sperm membrane physiology and an assessment of the individual ejaculate's sperm populations are necessary. Structural differences have been found in sperm membranes between fox species with different cryosurvival potential of their spermatozoa. Supplementation of lipids and detergents in cryoextenders may influence membrane fluidity of the surviving spermatozoa in a species‐dependent manner and influence capacitation. Immobilization of sperm prior to cryopreservation with subsequent slow release of sperm in the female genital tract may be a way to prolong the fertile life of sperm. In canids with a long oocyte maturation time, delayed capacitation may be beneficial.

Effects of the cryopreservation process on dog sperm integrity

“…However, frozen/thawed dog semen has a short lifespan due to loss of sperm cell integrity during the processes of cooling, freezing and thawing (Alhaider and Watson, 2009). Moreover, the fact that the bitch ovulate immature oocytes, which take 2 to 3 days to be read for fertilization, creates difficulties in determining the optimum time for insemination, making it even more important long functional life of the sperm after thawing (Peña et al, 1999;Alhaider and Watson, 2009;Farstad, 2012). Regardless, the viability of sperm when analyzed by motility is usually greater than the actual fertilization capacity due to changes that occur in cell membranes during the cryopreservation process (Maxwell and Watson, 1996).…”

Testis‐specific isoform of Na/K‐ATPase (ATP1A4) regulates sperm function and fertility in dairy bulls through potential mechanisms involving reactive oxygen species, calcium and actin polymerization

“…Contrary to our expectations, we didn't notice a decrease in the motility or viability after this incubation. This could be attributed to different sperm subpopulations; one subpopulation that has normal plasma membrane with a better cryotolerance and another subpopulation having capacitation‐like changes (Farstad, ). Perhaps there is a higher percentage of normal sperm with a viable plasma membrane compared to the cryo‐capacitated sperm subpopulation in HF and LF groups that is responsible for a physiological response after thawing.…”

A Novel Collection Technique for the Improvement of Semen Quality

“…12 In addition to the standard semen parameters, a sample was prepared at each time point to evaluate the percentage of spermatozoa that had undergone the acrosome reaction as an indicator of cells that have begun the process of capacitating. 13 Evaluations were made after preparing the cells using the chlorotetracycline stain technique of Keel and Webster and examining them using a Zeiss Standard microscope equipped with fluorescence (Carl Zeiss Inc., NY, NY). 14 The cells were examined using a 520μm excitation filter and a 570μm barrier filter.…”