Genome-wide association study for ketosis in US Jerseys using producer-recorded data

Area of Science:

• Animal Genetics and Genomics
• Dairy Cattle Metabolism
• Livestock Health Management

Background:

• Ketosis is a prevalent metabolic disorder in dairy cattle, significantly impacting herd health and productivity.
• While genetic factors influence ketosis, research specifically on Jersey cattle susceptibility remains limited.
• Understanding the genetic basis of ketosis is crucial for developing targeted breeding strategies.

Purpose of the Study:

• To estimate variance components for ketosis susceptibility in Jersey cattle.
• To identify specific genomic regions associated with ketosis incidence in this breed.
• To assess the feasibility of genetic selection for enhanced ketosis resistance.

Main Methods:

• Utilized producer-recorded health event data for ketosis from 23,865 Jersey cows.
• Employed a single-step genomic best linear unbiased prediction (BLUP) approach incorporating 1,750 genotyped animals and 60,671 single nucleotide polymorphism (SNP) markers.
• Calculated heritability, SNP effects, and variance explained by 10-SNP windows using specialized software (THRGIBBS1F90, postGSf90).

Main Results:

• Heritability estimates for ketosis susceptibility were 0.083 (pedigree-based) and 0.078 (genomic).
• Identified a significant SNP on chromosome 10 (66.3 Mbp) and a major 10-SNP window on chromosome 6 (56.1 Mbp) explaining 0.70% of variance.
• Gene Ontology and MeSH analyses revealed enrichment of terms related to immune function.

Conclusions:

• A significant genetic component underlies ketosis susceptibility in Jersey cattle.
• Genomic regions associated with ketosis have been pinpointed, providing targets for marker-assisted selection.
• Genetic selection for increased resistance to ketosis is a viable strategy for dairy herd improvement.