COOLING OF BOAR SPERMATOZOA PRIOR TO FREEZING AND PAST THAW QUALITY AND EVALUATION OF THE MEMBRANE STATE USING CHLORTETRACYCLIN (CTC)-STAINING

The influence of an extended holding time at room temperature (+18 deg rees C) before freezing on boar sperm quality was investigated. 17 eja culates were collected from 5 different, boars by separation in sperm rich and sperm poor fraction. The ejaculat were splitted, diluted 1+1 with Merck I-Medium, and submitted to three different treatments befor e freezing: 1. Sperm rich fraction, cooling to +20 degrees C for 1.5 h and subsequent cooling to +15 degrees C for 2.5 h; 2. Sperm rich frac tion, cooling to +18 degrees C for 4 h and subsequent holding time at +18 degrees C for 16h; 3. Whole ejaculate (sperm rich fraction plus se minal plasma), cooling to +18 degrees C for 4 hand subsequent holding time at +18 degrees C for 16h. Subjectively assessed post thaw motilit y (SMOT), computer measured motility (CMOT), and acrosome integrity (N AR), assessed by phase contrast microscopy were significantly (p<0.05) higher after extended holding time (procedure 2 and 3) compared to sh ort holding time (procedure 1). The exposure to seminal plasma during holding had ne significant effect. Chlortetracyclin (CTC) staining of sperm membranes gave no reliable information in the presence of an EDT A-containing preservation medium, used routinely in the preservation p rocess.