Abstract
SummaryIntramuscular fat (IMF) is one of the main meat quality traits for breeding programmes in livestock species. The main objective of this study was to identify genomic regions associated with IMF content comparing two rabbit populations divergently selected for this trait, and to generate a list of putative candidate genes. Animals were genotyped using the Affymetrix Axiom OrcunSNP Array (200k). After quality control, the data involved 477 animals and 93 540 SNPs. Two methods were used in this research: single marker regressions with the data adjusted by genomic relatedness, and a Bayesian multiple marker regression. Associated genomic regions were located on the rabbit chromosomes (OCU) OCU1, OCU8 and OCU13. The highest value for the percentage of the genomic variance explained by a genomic region was found in two consecutive genomic windows on OCU8 (7.34%). Genes in the associated regions of OCU1 and OCU8 presented biological functions related to the control of adipose cell function, lipid binding, transportation and localisation (APOLD1, PLBD1, PDE6H, GPRC5D and GPRC5A) and lipid metabolic processes (MTMR2). The EWSR1 gene, underlying the OCU13 region, is linked to the development of brown adipocytes. The findings suggest that there is a large component of polygenic effect behind the differences in IMF content in these two lines, as the variance explained by most of the windows was low. The genomic regions of OCU1, OCU8 and OCU13 revealed novel candidate genes. Further studies would be needed to validate the associations and explore their possible application in selection programmes.
Highlights
Intramuscular fat (IMF) contributes to improve organoleptic properties and sensory attributes of the meat, as demanded by consumers (Hocquette et al 2010)
A genome-wide association study (GWAS) was performed in order to identify genomic regions associated with IMF content in rabbits owing to the increasing importance of meat quality in livestock for consumers (Hocquette et al 2010; Pena et al 2016; Strucken et al 2017)
Our findings support the hypothesis that four genomic regions influence IMF content
Summary
Intramuscular fat (IMF) contributes to improve organoleptic properties and sensory attributes of the meat, as demanded by consumers (Hocquette et al 2010). Moderate-to-high heritability and large variability have been reported for livestock IMF traits, which argue for a good potential for improving meat quality through genetic selection. Selection are the IMF being recorded mainly at slaughter and the phenotyping process being costly. In this context, genetic marker selection based on quantitative trait locus (QTL) with high or moderate effect size could overcome some of these limitations. Studies carried out in beef cattle suggest that IMF could be influenced by a large number of genes (Strucken et al 2017). Studies in Japanese Black cattle have reported genomic markers with large effects on IMF or marbling score around the SCD, FASN, AKIRIN2, EDG1 and RPL27A genes (Gotoh et al 2014; Sukegawa et al 2014). Genomic studies to understand the genetic control of IMF are still needed
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