Year: 2013
Type: dissertation
Abstract: In this thesis my aims were to map genes affecting reproduction in cattle and to \nexplore the correlated effect of these genes on yield traits. This knowledge is expected \nto provide novel insights into the biological processes underlying reproduction traits \nand to identify individual causal polymorphisms or genetic markers for practical \napplication in marker-assisted and genomic selection strategies. \n \nA wide range of female fertility traits has been recorded for cattle indigenous to the \nNordic countries. Moreover, the trait definitions have been standardized across these \ncountries and the cattle industry has made its data available for research. The research \nfindings, themselves, highlight the benefit of such a comprehensive data source and \nincreasingly detailed genomic information ranging from relatively few microsatellites \nto full sequence profiles. \n \nIn manuscript I, a genome scan was performed using linkage analysis with \nmicrosatellite markers in order to identify genomic areas of interest. Twenty-six \nquantitative trait loci (QTL) affecting female fertility were identified. \n \nIn manuscript II, the trait fertility treatments were decomposed into sub-traits, four \nQTL for retained placenta were revealed. These QTLs and additional 24 QTL regions \ndiscovered in manuscript I, were analyzed for effects on yield traits. Sixteen of the \ngenomic regions containing QTL for female fertility also harbored QTL for milk \nproduction or milk composition traits. Twelve QTL regions with effects on nine \ndifferent fertility traits did not harbor any QTL for milk production or milk composition \ntraits. When. \n \nAn association study based on 50k single nucleotide polymorphism (SNP) data \nindicated significant associations for 4,474 SNPs with eight different female fertility \ntraits in Nordic Holstein. Of these SNPs, 152 were validated in both the Danish Jersey \nand the Nordic Red breeds, the most significant results were found on Chromosomes1, \n4, 9, 11 and 13. Small significant regions on chromosomes 4 and 13 were analyzed by \nsequencing to further focus the genomic region in which candidate genes and possible \ncausative mutations may be localized. \n \nSubsequently, new calving data was added and a validation study was performed, \nwhich confirmed 321 of 424 SNPs significantly associated with 14 calving traits. It was \ndetermined, however, that the analysis of the new data alone had low power, and an \nanalysis of the full data set was more powerful.
Author: Johanna K Höglund
Institution: Aarhus University
Language: English
Subfield: Genetics
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2154826412