Luzhong mutton sheep: inbreeding and selection signatures

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Sheep Breeding

Background:

• Intense artificial selection in Luzhong mutton sheep targets growth and reproduction.
• Phenotypic improvements suggest inbreeding, but genomic underpinnings remain unclear.

Purpose of the Study:

• Characterize runs of homozygosity (ROH) and inbreeding levels.
• Estimate inbreeding depression on growth and litter size.
• Identify positive selection signatures in the population.

Main Methods:

• High-density SNP array analysis.
• Runs of homozygosity (ROH) based inbreeding estimation.
• Genome-wide scan for selection signatures.

Main Results:

• Low inbreeding levels observed, negatively affecting litter size but not early growth.
• 160 genes identified under recent selection.
• Key genes associated with growth (GH-GHR-IGF1 axis) and litter size (BMPs) highlighted.

Conclusions:

• Previous breeding measures were effective, but inbreeding depression impacts litter size.
• Purging selection recommended to mitigate inbreeding depression.
• Genomic insights provided for improved breeding management of Luzhong mutton sheep.