title: In vitro evaluation of zwitterion buffers in diluents for freezing ram spermatozoa.
abstract: Diluents based on the zwitterion buffers Tes, Hepes and Pipes titrated to pH 7.0 with NaOH or Tris were compared with Tris-citrate diluents by assessment of post-thawing motility and acrosome integrity of frozen ram spermatozoa. Varying buffer osmolalities between 300 and 360 mosmol had no effect but there was a decrease (P < 0.001) in motility between 360 and 420 mosmol. There was a quadratic effect (P < 0.001) on motility of increasing glucose concentration in the diluent (30, 85, 140, 195 and 250 mM) with a maximum at 85 mM. At this sugar concentration, motility was higher (P < 0.001) for diluents containing glucose and fructose than lactose, sucrose or trehalose. Inclusion of egg yolk (optimum at 13.5% v/v; P < 0.05), centrifugation of the diluents (P < 0.01), use of low dilution rates (3 or 6-fold; P < 0.05) and freezing in pellets rather than minitubes or straws (P < 0.001) improved both the motility and acrosome integrity of spermatozoa in the zwitterion diluents. It is concluded that zwitterion buffers are superior to Tris-citrate in ram semen freezing diluents.
authors: Department of Animal Science, University of Sydney, NSW, Australia.
authors: F C
authors: FC
authors: Molinia
authors: G
authors: G
authors: Evans
authors: W M
authors: WM
authors: Maxwell
mesh_terms: D000818:Animals; D002021:Buffers; D015925:Cryopreservation; D005947:Glucose / Q000494:pharmacology; D007477:Ions; D008297:Male; D009994:Osmolar Concentration; D012756:Sheep; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D002021:Buffers; D007477:Ions; D005947:Glucose