Effects of fructo-oligosaccharides on survival and acrosome morphology of frozen-thawed boar spermatozoa

This experiment was carried out to clarify the effects on the survival and acrosome morphology of boar spermatozoa of fructo-oligosaccharides which might provide protection during freezing and thawing. Sperm-rich fraction of ejaculate was collected from 8 boars, diluted with pre-diluent, held at 15°C for 3h, centrifuged at 800g for 10min. Sperm were suspended in fructo-oligosaccharides diluents containing 20% egg yolk and cooled to 5°C for 2h. Before freezing, cooled semen was rediluted with an equal volume of diluent containing 6% glycerol and 1.48% OEP. Finally diluted semen was packaged in 5ml straw and frozen in liquid nitrogen vapour. Thawed semen at 40°C was rediluted with thawing diluent and then incubated at 37°C for 180 or 240min. to examine sperm survival and acrosome morphology. Fructo-oligosaccharides were prepared from sucrose through the transfructosylating action of enzymes. 1-kestose (GF2), Nystose (GF3), 1F-β-fructo-fructo-furanosylnystose (GF4) and Neosugar P (comprised of GF2, GF3 and GF4 at 40, 45 and 10%) were used for diluents. GF3 and GF4 were significantly effective for the maintenance of motility and acrosome morphology of frozen-thawed boar sperm. This result indicates that GF3 and GF4 are useful cryoprotectants for the cell.