Genetics and genomics of bovine mastitis resistance

Gunasegaram Narayana, Saranya

Genetics and genomics of bovine mastitis resistance

dc.contributor.advisor	Barkema, Herman
dc.contributor.advisor	Schenkel, Flavio
dc.contributor.author	Gunasegaram Narayana, Saranya
dc.contributor.committeemember	Miglior, Filippo
dc.contributor.committeemember	Kastalic, John
dc.contributor.committeemember	Orsel, karin
dc.date	2024-05
dc.date.accessioned	2024-01-11T19:44:58Z
dc.date.available	2024-01-11T19:44:58Z
dc.date.issued	2024-01-10
dc.description.abstract	Mastitis, a multifactorial infectious disease primarily caused by bacteria, remains a major economic challenge for the dairy cattle industry, despite decades of extensive research. To combat mastitis effectively, breeding for enhanced mastitis resistance through genetic selection, in combination with improved management strategies, offers a promising alternative. This thesis delves into the genetic and genomic aspects of mastitis, exploring the following key areas: 1) Genetic analysis of subclinical mastitis (SCM): By employing both linear and threshold models, the research presented in Chapter 2 investigated the genetic basis of SCM in early lactating heifers. Despite the relatively low heritability for six different SCM traits, this analysis revealed a notable genetic variation among sires, suggesting the possibility of long-term genetic selection to enhance heifer mastitis resistance. 2) Genetics of pathogen-specific intramammary infections (IMI): In Chapter 3, the genetic variation of overall and pathogen-specific IMI in nonclinical primiparous and multiparous cows was explored. The results demonstrated substantial exploitable genetic variability among daughters of sires for overall IMI and six IMI pathogen group traits. Furthermore, results indicated that the selection for lower somatic cell score (SCS) may not uniformly improve resistance to IMI from every pathogen group. 3) Underlying genetic architecture of mastitis resistance: Through a systematic review of genome-wide association studies and gene prioritization analysis, the research presented in Chapter 4 aimed to decipher the genetic architecture of mastitis resistance in dairy cattle. This comprehensive study identified numerous unique genes and quantitative trait loci, emphasizing the polygenic nature of mastitis, with many of the prioritized genes linked to immune response. 4) Genomic Copy Number Variants (CNVs) and SCS: The investigation in Chapter 5 uncovered three significant CNVs associated with SCS in Holstein cows, including four novel findings. Annotation analysis again identified numerous genes linked to immune response. 5) Genomic predictions of mastitis-related traits: Chapter 6 explored genomic prediction of mastitis-related traits in early first lactation of dairy cows, utilizing a single-step genomic approach. This approach demonstrated a substantial increase in validation and theoretical reliabilities for genomic prediction of genomic estimated breeding value of young animals compared to traditional pedigree-based prediction. In summary, this thesis highlights the genetic potential for enhancing mastitis resistance in dairy cattle, shedding light on various aspects of genetic and genomic influences on mastitis-associated traits. These findings provide valuable insights for the development of improved breeding strategies in the dairy industry.
dc.identifier.citation	Gunasegaram Narayana, S. (2024). Genetics and genomics of bovine mastitis resistance (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/117926
dc.identifier.uri	https://doi.org/10.11575/PRISM/42769
dc.language.iso	en
dc.publisher.faculty	Arts
dc.publisher.institution	University of Calgary
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.
dc.subject	Animal genetics
dc.subject	Animal breeding
dc.subject	Mastitis
dc.subject	Genomics
dc.subject	Epidemiology
dc.subject.classification	Agriculture
dc.subject.classification	Bioinformatics
dc.subject.classification	Genetics
dc.subject.classification	Veterinary Science
dc.subject.classification	Epidemiology
dc.title	Genetics and genomics of bovine mastitis resistance
dc.type	doctoral thesis
thesis.degree.discipline	Veterinary Medical Sciences
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.