| dc.description.abstract | Feed efficiency is a key factor in the economic outcomes of mink production systems, as the cost of feed accounts for the largest portion of their variable expenses. So far, the Canadian mink industry has relied solely on phenotypic selection as its main method of selection. Phenotypic data from 1,038-2,288 American mink with growth and feed efficiency traits were recorded in two different farms. In chapter 3, phenotypic and genetic parameters for growth and feed efficiency traits were estimated. The moderate heritabilities of feed efficiency-related traits in American mink, coupled with high favorable genetic correlations among them, confirmed the potential inclusion of these traits in genetic/genomic selection programs to achieve significant genetic improvements. The other chapters aimed to display the genetic architecture underlying feed efficiency-related traits. To this end, all individuals were genotyped using Affymetrix Mink 70K single nucleotide polymorphism (SNP) array. In chapter 4, the characteristics of copy number variations (CNVs) within the genome of American mink were determined through the examination of whole-genome sequencing data of 100 individuals. Biological pathway analysis on candidate genes overlapped with identified CNV regions (CNVRs) revealed several pathways related to growth (regulation of actin cytoskeleton, and cAMP signaling pathways), behavior (axon guidance, circadian entrainment, and glutamatergic synapse), lipid metabolism (phospholipid binding, sphingolipid metabolism and regulation of lipolysis in adipocytes), and immune response (Wnt signaling, Fc receptor signaling, and GTPase regulator activity pathways). Further, chapter 5 evaluated the association between CNVRs and 27 economically important traits in American mink. The findings revealed several significant CNVRs, which overlapped with genes reported to have impacts on growth and feed efficiency (ARID1B, APPL1, TOX, and GPC5), reproduction (GRM1, RNASE10, WNT3, WNT3A, and WNT9B), pelt quality (MYO10, and LIMS1), and Aleutian disease tests (IFNGR2, APEX1, UBE3A, and STX11). Similarly, chapters 6 and 7 aimed to identify runs of homozygosity (ROH) and their associations with growth and feed efficiency traits. The outcome suggested potential selection footprint in alignment with the breeding goals for mink, which include improving body length, reproductive performance, and fur quality. Furthermore, the results of the GWAS in Chapter 8 contributed to the identification of 153 potential candidate genes, some of which were known to have roles on the development of body size and feed efficiency, such as TUBB, CDKN1A, SRSF3, GPRC6A, RFX6, and KPNA5. Overall, the findings from this thesis provided useful information about the genetics of feed efficiency measurements for the mink industry, and identified potential candidate genes underlying feed efficiency traits, making them valuable as genetic markers in genomic breeding programs. | en_US |
