INFLUENCE OF MODIFIED TYRODES MEDIA ON MOTILITY OF COLD-STORED STALLION SPERMATOZOA

Two experiments were conducted to determine if the nonelectrolyte comp onents of a modified Tyrode's media could be eliminated without affect ing the percentage of stallion spermatozoa which recovered motility af ter storage at 5 degrees C. In the first experiment, diluents tested i ncluded the traditional 2.4% skim milk-5% glucose extender frequently used in the industry or that same extender supplemented at a 65:35 (vo l/vol) basis with either the modified high-potassium Tyrode's media (M T) or that same media minus lactate and pyruvate (MT-LP), bovine serum albumin (MT-BSA) or lactate, pyruvate and bovine serum albumin (MT-BS A,LP), Three ejaculates were collected from each of 4 stallions, For e ach ejaculate and test diluent combination, two aliquots of semen were cooled in a static cooling device. One aliquot was diluted and cooled after the seminal plasma was removed by centrifugation and the second aliquot was diluted and cooled without removing the seminal plasma. T he percentage of motile sperm was higher (P < .05) following 24 and 48 hours of cold storage for spermatozoa cooled in MT or MT-BSA compared with spermatozoa stored in SKMG, MT-LP or MT-BSA,LP. Removal of semin al plasma was beneficial (P < .01) when spermatozoa were stored for 48 hours in MT and MT-BSA. In the second experiment, all aliquots were c entrifuged to remove seminal plasma prior to resuspension in one of fo ur test diluents which consisted of MT-BSA and SKMG with and without t he HEPES buffer (MT-BSA+HEPES, MT-BSA-HEPES, SKMG+HEPES and SKMG-HEPES ). Exclusion of HEPES buffer from the Tyrode's media was not detriment al to the recovery of motile spermatozoa (P < .05), There was no advan tage (P < .05) to the inclusion of HEPES in the skim milk; motility of spermatozoa stored in the media supplemented with the modified Tyrode 's was superior (P < .05) to those which were not stored in diluents s upplemented with Tyrode's.