Genome-wide association study for milking speed in Fleckvieh cattle

Area of Science:

• Animal Genetics
• Dairy Cattle Breeding
• Quantitative Genetics

Background:

• Milking speed is crucial for udder health and labor efficiency in dairy cows.
• Genomic associations for milking speed are understudied.
• Fleckvieh cattle (Simmental) are a dual-purpose breed with economic importance.

Purpose of the Study:

• Identify genomic regions and genes affecting milking speed in Fleckvieh cattle.
• Investigate additive and dominance genetic effects on milking speed.
• Corroborate findings with other dairy breeds.

Main Methods:

• Genome-wide association studies (GWAS) using deregressed breeding values.
• Phenotypic analysis of milking speed in Fleckvieh bulls.
• GWAS for dominance effects using within-family variation (SD of yield deviations).

Main Results:

• Six single nucleotide polymorphisms (SNPs) on four autosomes showed significant additive effects on milking speed.
• Significant regions on BTA4 and BTA19 align with findings in other breeds.
• A significant signal for dominance effects was detected on BTA5, corroborating additive GWAS results.

Conclusions:

• Several strong genomic signals for milking speed in Fleckvieh cattle were identified.
• The strongest signals are supported by similar findings in Brown Swiss and Holstein Friesian cattle.
• Milking speed is a complex trait, and further research is needed to pinpoint causal genes and functions.