Abstract
BackgroundThe results obtained from genome-wide association studies (GWAS) often show pronounced disagreements. Validation of association studies is therefore desired before marker information is incorporated in selection decisions. A reliable way to confirm a discovered association between genetic markers and phenotypes is to validate the results in different populations. Therefore, the objective of this study was to validate single nucleotide polymorphism (SNP) marker associations to female fertility traits identified in the Nordic Holstein (NH) cattle population in the Nordic Red (NR) and Jersey (JER) cattle breeds. In the present study, we used data from 3,475 NH sires which were genotyped with the BovineSNP50 Beadchip to discover associations between SNP markers and eight female fertility-related traits. The significant SNP markers were then tested in NR and JER cattle.ResultsA total of 4,474 significant associations between SNP markers and eight female fertility traits were detected in NH cattle. These significant associations were then validated in the NR (4,998 sires) and JER (1,225 sires) dairy cattle populations. We were able to validate 836 of the SNPs discovered in NH cattle in the NR population, as well as 686 SNPs in the JER population. 152 SNPs could be confirmed in both the NR and JER populations.ConclusionsThe present study presents strong evidence for association of SNPs with fertility traits across three cattle breeds. We provide strong evidence that SNPs for many fertility traits are concentrated at certain areas on the genome (BTA1, BTA4, BTA7, BTA9, BTA11 and BTA13), and these areas would be highly suitable for further study in order to identify candidate genes for female fertility traits in dairy cattle.
Highlights
The results obtained from genome-wide association studies (GWAS) often show pronounced disagreements
The present study presents strong evidence for association of single nucleotide polymorphism (SNP) with fertility traits across three cattle breeds
We provide strong evidence that SNPs for many fertility traits are concentrated at certain areas on the genome (BTA1, BTA4, BTA7, BTA9, BTA11 and BTA13), and these areas would be highly suitable for further study in order to identify candidate genes for female fertility traits in dairy cattle
Summary
The results obtained from genome-wide association studies (GWAS) often show pronounced disagreements. There is often pronounced disagreement between different populations in the results obtained from genome-wide association studies (GWAS). As a result of the widespread use of artificial insemination (AI), effective dairy cattle population sizes are relatively small. The level of LD limits the precision of the QTL location, as SNPs at longer distances will exhibit association due to extended LD with causal mutation. This extended LD is not expected to exist across breeds, across-breed validation of associations may help to narrow down the QTL interval
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