Colloid centrifugation of fresh semen improves post-thaw quality of cryopreserved dromedary camel spermatozoa.

Colloids have been successfully used in a number of species to improve sperm populations for IVF and for cryopreservation The usefulness of Single Layer Centrifugation (SLC) for freezing dromedary camel spermatozoa in two different extenders was evaluated by examining the motility, viability, acrosome status, DNA integrity, and ability of cryopreserved sperm to penetrate oocytes in vitro in a heterologus IVF system. Two ejaculates from each of five males were divided into four aliquots: two were processed by SLC (selected) while two were centrifuged without colloid (control). Pellets were cryopreserved in Green Buffer or INRA-96® containing 3% glycerol and evaluated at 0 and 1 h post thawed. The SLC improved post-thaw total and progressive motility at 0 (both P < 0.0001) and 1 (P < 0.001; P < 0.01, respectively) h, and STR (both P < 0.05) and BCF (both P < 0.001) at 0 h. Sperm viability and acrosome integrity (both P < 0.001) were improved at both time points. Sperm frozen in Green Buffer had greater total and progressive motilities at 0 (both P < 0.001) and 1 (both P < 0.001) h than INRA-96® samples. Spermatozoa in Green Buffer also had a greater VAP, VCL and VSL at 0 h and improved viability and acrosome integrity at 0 h (P < 0.05; P = 0.001, respectively) and 1 h (P < 0.05; P < 0.001, respectively). Viability of SLC spermatozoa was improved in Green Buffer at 1 h (P < 0.05). Oocyte penetration (P < 0.05) and pronuclear formation (P < 0.01) were greater with SLC-selected spermatozoa than non-selected spermatozoa, regardless of extender. No difference was observed between treatments or extenders in the mean number of spermatozoa per oocyte penetrated. The SLC spermatozoa had less (P < 0.01) DNA fragmentation compared to controls. The DNA fragmentation was moderately and negatively correlated with penetration (r = -0.4162; P = 0.02) and pronuclear formation (r = -0.3390; P < 0.01). In conclusion, colloid centrifugation of spermatozoa and cryopreservation in Green Buffer improves post thaw motility variables and IVF performance of dromedary camel spermatozoa.