Development of a buffer system for dialysis of bovine spermatozoa before freezing. III. Effect of different inorganic and organic salts on fresh and frozen-thawed semen.
Three experiments were conducted to study the effect of inorganic and organic acids on survival of dialyzed bovine spermatozoa. Ejaculates were pooled, extended (1:10), dialyzed (1:50) for 2 h during cooling, and 1 h later they were frozen in pellets and stored in liquid nitrogen. The pellets were thawed in aluminum block depressions (preheated at 45 degrees C) and transferred to a test tube at room temperature as the last ice melted. Sperm motility was recorded in all samples before freezing and after thawing. The number of spermatozoa that passed through the Sephadex column was analyzed in all the postthaw samples. No statistical difference (P>0.05) was found between the use of potassium (KOH) or sodium hydroxide (NaOH) as titration bases. However, solutions containing calcium (Ca++) or magnesium (Mg++) provided significantly less (P<0.05) protection to the cells during freezing and thawing. No significant difference (P>0.05) was found in sperm survival of the postthaw samples when Ca++ or Mg++ were present. Inorganic salts of phosphates, carbonates or chloride provided significantly less protection to the cells than the control extenders with Na citrate (P<0.05). Results of the second experiment indicated that citrate, tartrate and oxalate salts provided superior (P<0.05) protection to the cells than salts of succinate, acetate or formate. It was concluded that an appropriate solution for use as a dialysate of extended bovine spermatozoa may be formulated as 30% (V/V) isosmotic Na salt of Piperazine-N-N-BIS (2-ethane sulfonic acid) (PIPES) plus 30% (V/V) isosmotic glucose plus 5% (V/V) glycerol plus 35% (V/V) of isosmotic solutions of Na or K citrate or tartrate, or a (1:1) combination of them.
Garcia
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Department of Animal Science University of Minnesota Saint Paul, MN 55108 USA.
Graham
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