Effect of the primary cooling rate on the motility and fertility of frozen-thawed rabbit spermatozoa


  • Tatsuhiro Maeda Saga University
  • Enqi Liu Saga University
  • Kazutoshi Nishijima Saga University
  • Shinji Yamaguchi Saga University
  • Masatoshi Morimoto Kumamoto Health Science University
  • Teruo Watanabe Saga University
  • Jianglin Fan University of Yamanashi
  • Shuji Kitajima Saga University




cryopreservation, cooling rate, motility, spermatozoa


In the present study, we examined the effect of primary cooling rates on the motility and fertility of frozen-thawed rabbit spermatozoa. Rabbit semen diluted with an egg-yolk acetamide extender was cooled from room temperature to 5°C at four different rates (-0.1, -0.2, -0.4, -0.8°C/min) as a primary cooling step, then semen was frozen in liquid nitrogen vapour. After thawing, sperm cooled at -0.1°C/min showed the highest motility (40.7 ± 7.3%); there were no significant differences between the motilities of the -0.1, -0.2, and -0.4°C/min groups. The motility of frozen-thawed sperm cooled at -0.8°C/min (29.2 ± 6.8%) was significantly lower than that of sperm cooled at -0.1 and -0.2°C/min. The viability (-0.1°C/min, 38.1 ± 4.0%; -0.8°C/min, 24.3 ± 7.3%) of frozen-thawed sperm was closely related to its motility (-0.1°C/min, 36.7 ± 7.2%; -0.8°C/min, 22.3 ± 4.7%). Quality of post-thaw motile sperm cooled at different rates was estimated by comparing the fertilisation ability of the -0.1 and -0.8°C/min groups following artificial insemination. There were no significant differences in pregnancy rates and mean litter sizes. These data suggest that cooling rabbit semen at rates ranging from -0.1 to -0.8°C/min affects the viability but not the fertilisation capacity of motile spermatozoa after thawing.


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Author Biographies

Tatsuhiro Maeda, Saga University

Analytical Research Center for Experimental Sciences, Saga University

Enqi Liu, Saga University

Analytical Research Center for Experimental Sciences, Saga University

Laboratory Animal Center, Xi’an University School of Medicine

Kazutoshi Nishijima, Saga University

Analytical Research Center for Experimental Sciences, Saga University

Shinji Yamaguchi, Saga University

Analytical Research Center for Experimental Sciences, Saga University

Teruo Watanabe, Saga University

Analytical Research Center for Experimental Sciences, Saga University

Jianglin Fan, University of Yamanashi

Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi

Shuji Kitajima, Saga University

Analytical Research Center for Experimental Sciences, Saga University


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