Quality assessment of cryopreserved New Zealand white rabbit spermatozoa in INRA-82 extender containing different cryoprotectants

Abstract

The present study aimed to evaluate the effect of supplementation of INRA-82 semen extender with different cryoprotectants (dimethyl sulphoxide; DMSO vs. dimethyl formamide; DMF) on the quality of white New Zealand rabbit buck spermatozoa. We also investigated the possible association between the synergistic action of DMSO and DMF and their relation with INRA-82 extender composition. Semen was collected and pooled from 8 adult rabbit bucks. Pooled semen samples were diluted 1:1 with INRA-82 extender supplemented with DMSO 8%, DMF 8% or a combination of DMSO 4% and DMF 4%. The diluted semen samples were cryopreserved in 0.25 plastic straws. After thawing, progressive motility, sperm viability, sperm abnormalities, membrane integrity, acrosome status, viability index and DNA integrity were evaluated. The results showed that dilution of rabbit buck semen in INRA-82 supplemented with DMSO and DMF (4% each) before freezing significantly (P<0.05) improved sperm motility (42.00%), percentage of live spermatozoa (45.30%), proportions of spermatozoa with intact acrosome (59.75%) and percentage of spermatozoa with non-fragmented DNA (86.04%), compared to those diluted in INRA-82 supplemented either with DMSO 8% (+9, +10, +5 and +7 percentage points, respectively) or with DMF 8% alone (+18 +18, +12 and +9 percentage points, respectively). In conclusion, dilution of rabbit buck semen before freezing with INRA-82 extender supplemented with a combination of DMSO 4% and DMF 4% improved quality of frozen-thawed New Zealand White rabbit spermatozoa. Furthermore, our results also suggest that supplementation of INRA-82 with DMSO or with DMF alone at higher concentrations deteriorates the sperm quality.