Effects of single layer centrifugation (SLC) on bull spermatozoa prior to freezing on post-thaw semen characteristics.
Single layer centrifugation (SLC) has been shown to select the most robust spermatozoa from the ejaculate in several species. Here the effects of SLC prior to freezing on various parameters of frozen-thawed bovine sperm quality are reported. Semen from 8 bulls was layered on top of a species-specific colloid, Bovicoll. After centrifugation for 20 min at 300 g, the resulting sperm pellet was resuspended in OPTIXcell®(IMV Technologies, l'Aigle, France); the SLC-selected sperm samples and uncentrifuged controls were frozen. On thawing, all sperm samples were analysed for membrane integrity, production of reactive oxygen species, mitochondrial membrane potential (MMP) and chromatin integrity. The SLC-treated samples had a higher percentage of live, superoxide-positive spermatozoa than uncentrifuged samples (27.9 ± 5.1% versus 21.7 ± 6.7%; p = .03). They had a higher proportion of spermatozoa with high mitochondrial membrane potential than uncentrifuged samples (55.9 ± 8.2% versus 40.5 ± 15.1%; p = .03) and also a lower proportion of spermatozoa with low mitochondrial membrane potential than non-treated samples (42.0 ± 8.5% versus 55.9 ± 14.4%; p = .04). No significant effects of treatment were found for membrane integrity or chromatin integrity. The effect of bull was significant on the proportions of dead, superoxide-positive spermatozoa and live, hydrogen peroxide-negative spermatozoa, as well as on membrane integrity, but it was not significant for mitochondrial membrane potential or chromatin integrity. These results suggest that SLC selects the most metabolically active bull spermatozoa from the rest of the population in normal ejaculates; the pattern of reactive oxygen species production may be different in SLC-selected spermatozoa compared to unselected samples.
Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.|Faculty of Veterinary Sciences, Mahasarakham University, Maha Sarakham, Thailand.
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Nongbua
Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
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Johannisson
VikingGenetics, Skara, Sweden.
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Edman
Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
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Morrell
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002498:Centrifugation / Q000379:methods* / Q000662:veterinary*; D015925:Cryopreservation / Q000662:veterinary*; D004249:DNA Damage; D005615:Freezing; D008297:Male; D053078:Membrane Potential, Mitochondrial; D017382:Reactive Oxygen Species; D012661:Semen; D055101:Semen Analysis; D013094:Spermatozoa / Q000502:physiology
D017382:Reactive Oxygen Species
Bovicoll; cryopreservation; metabolic activity; reactive oxygen species production; sperm quality