Development of a buffer system for dialysis of bovine spermatozoa before freezing. II. Effect of sugars and sugar alcohols on posthaw motility

Two experiments were conducted to evaluate the effect of different levels of sugars (glucose, lactose and raffinose) and the effect of those sugars (C(3) to C(6)) or their correspondent sugar alcohols on the dialysis of bovine semen. First, the effect of isosmotic solutions of glucose, lactose or raffinose at five different levels (0, 25, 50, 75, 95% V/V) on sperm motility of semen dialyzed prior to freezing were studied. These levels were used in extenders and dialysates, and the final volume was complemented with Piperazine-N-N-BIS (2-ethane sulfonic acid (PIPES) titrated to pH 7.0 with TRIS (hydroxymethyl) amino-methane (TRIS) to form PIPEST or a 1:1 (V/V) combination between PIPEST and sodium citrate solutions. In the second experiment, 30% of the buffer volume contained solutions of sugars (C(3) or C(6)) or their correspondent sugar alcohol, and the final volume was completed with PIPEST-citrate buffer. Semen aliquots were extended (1:10) and dialyzed (1:50) for 2 h while cooling from 37 to 5 degrees C in semipermeable dialysis bags of 12,000 to 14,000 molecular weight cut off. The samples were frozen in pellets 1 h after dialysis was terminated. Sperm survival was significantly higher in PIPEST-citrate than in PIPEST buffer alone (P<0.05). No significant difference (P>0.05) was obtained between the use of glucose or lactose or between lactose and raffinose. High levels of sugar appeared to be detrimental to sperm motility of fresh and thawed semen samples. Motility of cells extended in buffers containing 30% (V/V) isosmotic solutions of glucose, galactose, ribose, xylose, arabinose or their correspondent sugar alcohols was significantly higher (P<0.05) than their motility in extenders without sugar.