Disentangling Mature Cow Weight and Body Condition Score: A Comparative Single-Step GWAS of Phenotypic Pre-adjustment...

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Genomic Analysis

Background:

• Mature cow weight (MWT) is genetically correlated with body condition score (BCS), influencing sire rankings.
• Different modeling strategies for accounting for BCS can alter selection outcomes for MWT.
• The recursive modeling approach (MWTRM) provides MWT genetically independent of BCS, contrasting with phenotypic pre-adjustment (MWTadj).

Purpose of the Study:

• To compare the genomic architecture captured by MWTadj and MWTRM.
• To determine if different modeling approaches reveal distinct genetic architectures or statistical artifacts.
• To identify genes and pathways associated with MWT under different modeling strategies.

Main Methods:

• Genome-wide association studies (GWAS) were conducted on MWTadj and MWTRM.
• Functional genomic analyses were performed to annotate significant single nucleotide polymorphisms (SNPs).
• Gene and pathway enrichment analyses were used to compare results between models.

Main Results:

• Significant SNP associations were identified for both MWTadj (42 SNPs) and MWTRM (44 SNPs), with overlap.
• MWTRM identified more shared genes with unadjusted MWT (33 vs. 19) and shared more pathways (28/31 vs. 0).
• MWTRM associated with growth, feed efficiency, and carcass traits, while MWTadj identified distinct genes/pathways.

Conclusions:

• MWTRM captures a more relevant genetic architecture for MWT, particularly for growth and feed efficiency, compared to MWTadj.
• Both models identify core biological signals for MWT, but MWTRM provides a more biologically interpretable genetic basis independent of BCS.
• The choice of modeling strategy significantly impacts the understanding of the genetic underpinnings of MWT.