Seasonal influence on expression of heat shock proteins (HSP70 and HSP90) vis-à-vis functional competence of Gir bull semen

Abstract

The success of assisted reproduction relies on functional competence of frozen-thawed semen. Heat stress affects protein folding leading to aggregation of mis-folded proteins. Hence, a total of 384 (32 ejaculates/bull/season) ejaculates from six matured Gir bulls were used to evaluate physico-morphological parameters, the expression of HSPs (70 and 90) and fertility of frozen-thawed semen. The mean percent individual motility, viability and membrane integrity were significantly (p < 0.01) higher in winter compared to summer. Out of 1200 Gir cows inseminated, 626 confirmed pregnant and the mean conception rate of winter (55.04 ± 0.35) was significantly (p < 0.001) higher than summer (49.33 ± 0.32). A significant (p < 0.01) difference in concentration of HSP70 (ng/mg of protein) but not HSP90was observed between the two seasons. The HSP70 expression in pre-freeze semen of Gir bulls had significant positive correlation with motility (p < 0.01, r = 0.463), viability (p < 0.01, r = 0.565), acrosome integrity (p < 0.05, r = 0.330) and conception rate (p < 0.01, r = 0.431). In conclusion, the season influences physico-morphological parameters and expression of HSP70 but not HSP90 in Gir bull semen. The HSP70 expression is positively correlated with motility, viability, acrosome integrity and fertility of semen. The semen expression of HSP70 may be utilized as biomarker for thermo-tolerance, semen quality and fertilizing capacity of Gir bull semen.

Keywords:

• Gir bull semen
• HSP70
• HSP90
• seasonal influence
• conception rate

Acknowledgements

The authors are highly thankful to the Head, Cattle Breeding Farm and Dean, Veterinary College, Junagadh, Gujarat for providing the permission and funds for research work. The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Ethical approval

The research was the part of doctoral degree and was approved by the University research approval committee, headed by the Director of Research and Dean, postgraduate studies for ethical use of animals. No experiments were done on the animals and the semen collection as well as artificial insemination was routine practice at the cattle breeding farm. Hence, as per norms no separate ethical approval was required.

Author contributions

Authors, G. B. Solanki, F. S. Kavani, A. J. Dhami, and Tapas Patbandha were involved in planning of work, and analysis of data and manuscript preparation. G. B. Solanki, V. K. Singh, H. H. Savsani and B. Kumar were involved in execution of work and manuscript preparation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated during the current study are available with the authors and will be made available on reasonable request.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.