Susceptibility of boar spermatozoa to heat stress using in vivo and in vitro experimental models

Pena, Santiago T., Stone, Felicity, Gummow, Bruce, Parker, Anthony J., and Paris, Damien B.B.P. (2021) Susceptibility of boar spermatozoa to heat stress using in vivo and in vitro experimental models. Tropical Animal Health and Production, 53. 97.

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Induction of heat stress as an experimental procedure in animals is commonly used to examine heat-related impacts on sperm quality. This study aimed to develop potential heat stress models that could be used at any time of the year, to advance the study of seasonal infertility in the pig under controlled conditions. Heat stress was induced by either housing boars (n = 6) at 30 °C inside a hot room for 42 days (55–65% humidity; LD 12:12 h; in vivo), or by heating boar semen (n = 7) for 30 min at various temperatures (35.5, 38.8, 40, 42, 46, 50, 54 and 60 °C; in vitro). Sperm motility was then characterized by computer-assisted sperm analysis (CASA; IVOS version 10: Hamilton Thorne, USA), and DNA integrity was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) and flow cytometry. Our in vivo hot room model induced biologically meaningful levels of DNA damage in boar spermatozoa (10.1 ± 1.9 hot room vs. 6.7 ± 1.7% control; P > 0.05), although not statistically significant from controls. Moreover, sperm concentration and motility parameters did not differ between treatments (P > 0.05). Compared to the 38.8 °C control, our in vitro heat shock model significantly increased sperm DNA damage after incubation at 54 and 60 °C (3.0 ± 1.0, 2.9 ± 1.0, 1.2 ± 0.3, 2.5 ± 0.7, 9.0 ± 3.7, 16.2 ± 7.1, 14.2 ± 5.8 and 41.8 ± 18.6% respectively; P ≤ 0.05). However, these temperatures rendered sperm completely immotile or dead, with most motility parameters declining rapidly to zero above 40 or 42 °C. In conclusion, our results suggest that temperature combined with individual factors may contribute to a boar’s overall susceptibility to heat stress. Refinement of these models particularly of the in vitro heat shock model could be further pursued to overcome environmental variability, reduce whole animal experiments and provide a putative diagnostic fertility screening tool to evaluate heat tolerance in the boar.

Item ID: 54231
Item Type: Article (Research - C1)
ISSN: 1573-7438
Keywords: boar, summer infertility, sperm DNA damage, heat stress; pig, hot room, sperm motility
Copyright Information: Copyright © 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.
Funders: James Cook University (JCU), AusAID
Projects and Grants: JCU Development Grant, JCU College of Public Health, Medical and Veterinary Sciences PhD Research Funds, AusAID Australia Awards Scholarship
Date Deposited: 10 Feb 2021 22:59
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3003 Animal production > 300305 Animal reproduction and breeding @ 60%
31 BIOLOGICAL SCIENCES > 3101 Biochemistry and cell biology > 310102 Cell development, proliferation and death @ 40%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830308 Pigs @ 50%
97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 25%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960302 Climate Change Mitigation Strategies @ 25%
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