Extending the viability of emu spermatozoa during in vitro storage by manipulation of temperature and diluent potassium concentration

Abstract

1. Survival of emu spermatozoa during in vitro storage is not affected by increasing the extracellular [K⁺] to the point where it does not adversely affect spermatozoa function.

2. In three experiments, the effects were studied of [K⁺] in a diluent in the range 12·5–80 mM/l on emu spermatozoa survival for up to 48 h at 5, 10 or 20°C.

3. At the end of the storage period, spermatozoa viability, motility, fertilising ability and morphology were measured.

4. In Experiment 1, spermatozoa viability and morphology were adversely affected after storage (P < 0·001) only in the diluent containing 80 mM/l [K⁺] whereas spermatozoa motility decreased as [K⁺] increased from 12·5 to 80 mM/l.

5. In Experiment 2, during storage at 5°C, the spermatozoa viability was comparable among any of the diluents (standard or modified) but morphology was better (P < 0·001) in all of the modified diluents than in the standard E3 diluent.

6. In Experiment 3, after 48 h of storage in a diluent containing 40 mM/l of [K⁺], the spermatozoa functions were better preserved at 10°C than at 5 or 20°C.

7. It is concluded that a higher than physiological level of potassium can be used in a diluent without detrimental effect on emu spermatozoa survival during 48 h storage and that the best outcome was with storage at 10°C rather than 5 or 20°C.

Acknowledgements

We thank the staff of the Animal Care Unit of the University of Western Australia for their cooperation. The Rural Industries Research and Development Corporation supported this study. We are also thankful to the Endeavour Awards, administered by the Department of Education, Employment and Workplace Relations, Government of Australia, for providing the post graduate scholarship to the corresponding author that enabled him to carry out this research. Study leave granted by the government of Himachal Pradesh, India to the corresponding author is gratefully acknowledged.