Association between SNP variation and muscling measured by computed tomography in Texel sheep

What is it about?

Approximately, 70% of all slaughtered lambs are crossbred derived from matings of terminal sire rams to a maternal sheep breed, mostly mules. This is the first study based on a genomewide association approach that investigates the links between some economically important traits including Computed Tomography (CT) measurements and molecular polymorphisms in Texel sheep. Our main aim was to identify Single Nucleotide Polymorphisms (SNP) associated with growth, carcass, health and welfare traits of the Texel sheep breed. This study used data from 384 Texel rams. Data comprised 10 traits, including 2 CT measured traits. The phenotypic data were placed in four categories: growth traits, carcass traits, welfare traits and maternal traits. De-regressed estimated breeding values (EBV) for these traits together with sire genotypes derived with the Ovine 50K SNP array of Illumina were jointly analysed in a genome wide association analysis. Linkage disequilibrium (LD) among adjacent SNP (r2 = 0.25 ± 0.019) and within 1 Mb intervals (r2=0.063 ± 0.005) was estimated. Eight novel chromosome-wise significant associations were found for carcass, growth, health and welfare traits. The significant markers were either intron variants or intergenic variants. This study is a first step to search for genomic regions controlling economically important traits related to body and carcass composition in a terminal sire sheep breed using a 50K SNP genome-wide array.

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Why is it important?

In 2013, the global number of sheep exceeded one billion. One third of all lamb meat in the European Union is produced in the UK. Growth and meat production traits are significant economic traits in sheep. The Texel breed is the most popular terminal sire breed in the UK, mainly selected for muscle growth and lean carcasses. To find associations between SNPs and muscling traits is very important for the further development of strategies to identify causal variants associated with CT measures and other commercial traits in sheep. Independent studies are needed to confirm these results and identify candidate genes for the studied traits.