Genome-wide association study for calving traits in Holstein-Friesian dairy cattle

Area of Science:

• Animal Genetics and Breeding
• Quantitative Genetics
• Livestock Production

Background:

• Dystocia and perinatal mortality significantly impact cattle productivity and welfare.
• These traits are economically important and included in national breeding goals.
• The genetic basis for these traits is not fully understood.

Purpose of the Study:

• To identify bovine genomic regions associated with calving difficulty (direct and maternal) and perinatal mortality.
• To pinpoint specific genetic markers for these economically important traits.

Main Methods:

• Utilized a Bayesian approach with 43,204 single nucleotide polymorphisms (SNPs).
• Analyzed data from up to 1,970 Holstein-Friesian bulls.
• Investigated associations on multiple bovine chromosomes.

Main Results:

• Identified significant SNPs on chromosomes 5, 6, 11, 12, 17, 18, and 28 associated with calving traits.
• Found novel genomic regions linked to growth, stature, and bone morphology also associated with calving performance.
• Located a key SNP for perinatal mortality near the SLC26A7 gene and linked HHIP gene to direct calving difficulty.

Conclusions:

• Genomic regions associated with calving difficulty and perinatal mortality were identified.
• Findings support genetic covariances between traits and suggest potential for resolving genetic antagonisms through selective breeding.
• Specific genomic regions, including one on chromosome 18, show strong evidence for causative mutations impacting calving traits.