Effect of Detergents Based on Sodium Dodecyl Sulfate on Functional Metrics of Frozen–Thawed Collared Peccary (Pecari tajacu) Semen

SIMPLE SUMMARY: Constant threats to wildlife have led countless researchers to develop or improve conservation strategies, among which the formation of biobanks stands out. The systematic storage of male gametes in freezing temperatures is useful for future use in assisted reproduction and for improving the reproductive management of rare species. In this study, the effect of including Equex STM(®) paste or different concentrations of sodium dodecyl sulfate (SDS) on various functional metrics of frozen and thawed peccary semen, such as sperm kinetic parameters, membrane functionality and integrity, mitochondrial activity and binding capacity, was verified. In parallel, sperm longevity was evaluated through a thermal resistance test. In general, it was demonstrated that the addition of 0.1% SDS to the Tris–egg yolk–glycerol diluent favored the maintenance of the sperm kinetic parameters of peccaries during freezing and thawing procedures. ABSTRACT: We evaluated the effects of detergents based on sodium dodecyl sulfoxide (SDS) on the functional parameters of collared peccary frozen–thawed sperm. Semen aliquots from ten individuals were diluted in a Tris–egg yolk–glycerol extender alone or with 0.5% Equex STM(®) paste or SDS (at 0.1%, 0.3% or 0.5% (v/v) concentration). Samples were fast frozen in liquid nitrogen with a post-thaw evaluation of motility, membrane functionality and integrity, mitochondrial activity, sperm binding ability and thermal resistance. The treatments without SDS (41.8 ± 3.5%) and those containing Equex (41.8 ± 4.4%) or 0.1% SDS (41.2 ± 5.5%) provided greater sperm motility (p < 0.05) than those containing SDS 0.3% (30.5 ± 4.7%) and 0.5% (31.2 ± 6.3%). Immediately after thawing, only treatments containing 0.1% SDS effectively preserved sperm straightness (STR) when compared to the negative control. All treatments preserved the amplitude of lateral head (ALH) and straightness (STR) during a thermal resistance test (p > 0.05), but SDS 0.5% impaired the membrane functionality and mitochondrial activity after thawing (p < 0.05). All treatments provided a similar recovery of sperm binding ability after thawing (p < 0.05). Our results showed that the addition of 0.1% SDS to the Tris–yolk–glycerol extender optimized the freeze–thaw recovery of peccary semen.