Development of extender and techniques for frozen turkey semen. 1. Development

An extender for turkey semen with a frozen-thawed recovery of greater than or equal to 50% motile spermatozoa and a vigorous swirl was developed. The effect of glucose, a comparison of 10 different sugars in the extender, the use of sodium acetate and potassium acetate, the ratio of dimethylsulfoxide to ethylene glycol, the percent total cryoprotectant, equilibration time, and osmotic pressure were all tested. Replacement of approximately half of the extender with an iso-osmolar glucose solution yielded higher percentages of motile spermatozoa with both fresh and frozen-thawed semen samples. Replacement of glucose with other carbohydrates did not enhance recovery of frozen-thawed semen. The proportion of sodium and potassium acetates to TESNaK2 in the extender had no effect on motility. Approximately equal proportions of ethylene glycol to dimethylsulfoxide, with a final concentration of 11.2% after dilution, produced at or near optimal recovery of spermatozoal motility after freezing. Twenty to 90 min equilibration times before freezing yielded significantly higher recovery of motile sperm postthaw than shorter periods. A wide range of extender osmotic pressures were compatible with recovery of spermatozoal motility postthaw. The final extender consisted of 4.70 g sodium acetate, 3.39 g potassium acetate 9.23 g TES, .353 g sodium hydroxide, .492 g potassium hydroxide, 32.00 g glucose, H2O q.s. 1000 ml, 370 mOsm/kg, pH 7.2. Ethylene glycol and dimethylsulfoxide were added (1:1 ratio) for a final concentration of 11.2% cryoprotectant after dilution. Semen was held undiluted for 6 min, extended 1:4 at 22 C, and equilibrated for 30 min at 0 C before pellet freezing.