Digital Public Defence: Birgitte Narud
MSc Birgitte Narud at Institute of Basic Medical Sciences will be defending the thesis Reproductive potential and semen attributes in Norwegian Red bulls for the degree of PhD (Philosophiae Doctor).
The public defence will be held as a video conference over Zoom.
The defence will follow regular procedure as far as possible, hence it will be open to the public and the audience can ask ex auditorio questions when invited to do so.
Due to copyright reasons, an electronic copy of the thesis must be ordered from the faculty. In order for the faculty to have time to process the order, it must be received by the faculty no later than 2 days prior to the public defence. Orders received later than 2 days before the defence will not be processed. Inquiries regarding the thesis after the public defence must be addressed to the candidate.
Digital Trial Lecture – time and place
- First opponent: Professor Ann Van Soom, Faculty of Veterinary Medicine, Ghent University, Belgium
- Second opponent: Professor Poul Hyttel, Department of Veterinary and Animal Sciences, University of Copenhagen, Denmark
- Third member and chair of the evaluation committee: Professor Bjørn Steen Skålhegg, University of Oslo
Chair of the Defence
Professor Christian Drevon, University of Oslo
Elisabeth Kommisrud, Professor, Høgskolen i Innlandet
With the introduction of genomic selection in cattle breeding, younger bulls without any fertility records have been recruited for semen production. Bull fertility has a major impact on the overall bovine reproductive efficiency. Thus, it is of interest to the cattle breeding industry to have laboratory tests that can predict the fertilization potential of a semen sample.
The main aim of this thesis was to study sperm quality traits as well as underlying factors affecting reproductive potential of Norwegian Red bulls. The study populations were young bulls of both 14 and 17 months of age and a group of bulls with contrasting field fertility. The goal was to detect potential biomarkers related to bull maturation and fertility, for implementation at the breeding station.
Results showed that even small differences in age significantly affected sperm quality parameters, semen production efficiency and level of metabolites in semen from young Norwegian Red bulls. However, young bulls of 14-15 months of age were mature enough for their semen to fulfil successful fertilization.
Bulls of contrasting fertility differed in several aspects of sperm functionality and intracellular metabolite contents. Multiple correlations between metabolites, sperm quality parameters and field fertility indicated that metabolomics might be a useful tool in the identification of biomarkers for male fertility. A potential prediction model including the parameters DNA fragmentation index, aspartic acid, Fe and Zn explained 59% of the variability in bull field fertility.
The study of sperm DNA methylation patterns revealed several genes and pathways that offer useful insight into bull maturation and reproductive capacity.
Overall, it was demonstrated that conventional sperm quality parameters only partly explain the variation in bull fertility. Underlying factors affecting fertility might be elucidated by metabolomics and sperm DNA methylation analysis.
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