F.E. Van Niekerk

The effect of cryopreservation on the survivability, viability and motility of epididymal African buffalo (Syncerus caffer) spermatozoa.

The effect of cryopreservation on the viability and motility of epididymal African buffalo spermatozoa was studied in samples obtained from 17 and 13 animals in 1995 and 1996, respectively. Cryopreservation significantly reduced the viability and motility of the epididymal spermatozoa. The average percentage of live (+/- SE) spermatozoa declined significantly from 90.4 +/- 2.0% (1995) and 84.4 +/- 1.1% (1996) in fresh epididymal samples, to 57.0 +/- 2.0% and 56.3 +/- 1.1%, respectively, in frozen-thawed samples. The acrosomal integrity (+/- SE) of spermatozoa declined from 89.3 +/- 2.3% (1995) and 93.3 +/- 2.2% (1996) to 50.2 +/- 2.3% and 37.5 +/- 2.2%, respectively. In 1995, this effect was largely associated with the thermal equilibration prior to cryopreservation.

Sperm viability and morphology of two genetically diverse Merino lines.

Microscopically evaluated sperm parameters, as well as computer-aided sperm motility analysis (CASMA), were used to assess sperm quality and the effect of cryopreservation on ram semen obtained from two genetically diverse Merino lines. These lines were divergently selected on maternal ranking values for multiple rearing ability from the same base population since 1986. Replacements in the high (+) line were preferentially the progeny of ewes rearing >1 lamb per joining. Progeny of ewes rearing <1 lamb per joining was preferred as replacements in the low (-) line. Sperm quality, as assessed by percentages of live, abnormal and acrosome-intact spermatozoa as well as by motility, was independent (P < or = 0.20) of line, time of sampling and their interaction in ejaculated samples obtained from the eight rams used as sires in 1995. Sperm quality of frozen-thawed samples was adversely affected (P < or = 0.01) by cryopreservation and thawing at 35 degrees C for 30 s relative to fresh ejaculated samples. No consistent differences between lines were found in epididymal sperm samples obtained from 12 slaughtered rams (6 from each line). The adverse effect (P < or = 0.05) of cryopreservation and thawing at 35 degrees C for 30 s on sperm viability and motility was also demonstrated for these samples.