Consequences of Testicular Heat Stress and Potential Amelioration Strategies

Mohamed, Abdallah Mohamed Shahat

Consequences of Testicular Heat Stress and Potential Amelioration Strategies

dc.contributor.advisor	Kastelic, John
dc.contributor.author	Mohamed, Abdallah Mohamed Shahat
dc.contributor.committeemember	Kovalchuk, Igor
dc.contributor.committeemember	Pajor, Edmond
dc.contributor.committeemember	Pearson, Jennifer
dc.contributor.committeemember	Thundathil, Jacob
dc.contributor.committeemember	de Graaf, Simon
dc.contributor.committeemember	Honaramooz, Ali
dc.date	2023-02
dc.date.accessioned	2023-01-17T20:33:51Z
dc.date.available	2023-01-17T20:33:51Z
dc.date.issued	2023-01-12
dc.description.abstract	Heat stress (HS) is a worldwide problem due to temperature elevations associated with global warming. Monitoring temperature changes in testes and scrotum over time is important to understand thermoregulatory capacity of testes and scrotum. Temperature data loggers (DLs) are reliable devices that can be implanted in scrotal subcutaneous tissues to serially record intrascrotal temperature without altering animal behavior. Testicular HS causes a variety of outcomes, depending on the degree and duration of testicular heating. Some effects of testicular HS on testicular tissues, blood flow and sperm quality and attempts to prevent them, by treating animals or semen extender, have been reported. The overall objective of this study was to investigate impacts of HS on sperm quality and use various ameliorative strategies to mitigate these detrimental effects, using bull and ram models. We validated data loggers as a reliable, less invasive and serial method to measure intrascrotal temperature. Scrotal subcutaneous temperature was significantly increased by scrotal insulation or whole-body heating, but not by scrotal neck insulation; however, all three heat-stress models decreased sperm motility and morphology in bulls and rams. In addition, our hypothesis that melatonin or L-arginine improve quality of frozen-thawed sperm from HS rams was supported; 1 mM of either gave best results, except 0.5 mM minimized DNA Fragmentation Index (DFI%). Moreover, during hot weather, bulls voluntarily accessed shade, significantly lowering scrotal subcutaneous temperatures and improving sperm quality. In rams exposed to testicular HS, slow-release melatonin significantly improved testicular blood flow, protected sperm motility and morphology, and lessened HS-induced reductions in post-thaw sperm quality. Therefore, melatonin has potential for mitigating effects of testicular HS under field conditions.	en_US
dc.identifier.citation	Mohamed, A. M. S. (2023). Consequences of testicular heat stress and potential amelioration strategies (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.	en_US
dc.identifier.uri	http://hdl.handle.net/1880/115685
dc.identifier.uri	https://dx.doi.org/10.11575/PRISM/40603
dc.language.iso	eng	en_US
dc.publisher.faculty	Veterinary Medicine	en_US
dc.publisher.institution	University of Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.subject	Heat stress	en_US
dc.subject	Testes	en_US
dc.subject	Sperm	en_US
dc.subject	Melatonin	en_US
dc.subject	L-arginine	en_US
dc.subject	Shade	en_US
dc.subject.classification	Veterinary Science	en_US
dc.title	Consequences of Testicular Heat Stress and Potential Amelioration Strategies	en_US
dc.type	doctoral thesis	en_US
thesis.degree.discipline	Veterinary Medical Sciences	en_US
thesis.degree.grantor	University of Calgary	en_US
thesis.degree.name	Doctor of Philosophy (PhD)	en_US
ucalgary.item.requestcopy	true	en_US