Two myostatin single nucleotide polymorphisms have significant effects on carcass
traits of UK commercial Charollais sheep populations
Hadjipavlou, G.†, Matika, O.†, Clop, A.‡, and Bishop S. C.†
†
Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK
‡
Genesis Faraday Partnership, Roslin, Midlothian EH25 9PS, UK
Phenotypic and genotypic data on 338 Charollais lambs from 29 sire families were
analysed to determine the effects of two single nucleotide polymorphisms (SNPs) on
the economically important production traits of muscle and fat depth. These two
SNPs, located in the myostatin region of ovine chromosome 2, were previously
detected in Belgian Texel rams exhibiting muscle hypertrophy. Genotyping of Suffolk
rams from commercial flocks showed that the SNPs associated with muscular
hypertrophy were not segregating, whereas in commercial Texel rams these SNPs
were nearly fixed. In the commercial Charollais population both myostatin SNPs were
segregating. These two SNPs had significant effects on muscle and fat depth
characteristics, both when fitted together or separately. For muscle depth, the
difference between the alternate homozygotes was 2.40±0.69mm (p<0.001) for SNP1
and 1.94±0.60mm (p=0.002) for SNP2. The dominance deviation was -1.04±0.38mm
for SNP1 and -0.70±0.35mm for SNP2. For fat depth, the difference between alternate
homozygotes was 0.18±0.09mm1/2 (p=0.033) for SNP1 and 0.22±0.08mm1/2
(p=0.004) for SNP2. The dominance deviation was -0.05±0.05mm1/2 for SNP1 and
-0.01±0.05 mm1/2 for SNP2. Total genetic variances for fat and muscle depth in the
Charollais population were estimated from a dataset comprising 56466 phenotypic
records and 128806 pedigree records. Heritabilities for muscle and fat depth were
estimated to be 0.31 and 0.33, respectively. Assuming allele frequencies of 0.5, SNP1
genotype information explains 24% of the total additive genetic variance for muscle
depth, and 9% of the total additive genetic variance for fat depth. Full characterization
of these SNP effects on production traits in Charollais sheep may allow SNP-assisted
selection to be incorporated into commercial sheep breeding programs.