Molecular Characterization of Livestock Disease Resistance Traits

Abstract

Livestock disease resistance is a heritable, polygenic trait of critical importance to global food security and sustainable
animal production. This study presents a comprehensive molecular characterization of disease resistance loci across
three commercially important livestock species--cattle (Bos taurus), sheep (Ovis aries), and pigs (Sus scrofa)--using a
combined approach of genome-wide association study (GWAS), candidate gene sequencing, and transcriptomic profiling
of immune tissues. A total of 1,248 animals sampled from eleven European farms were genotyped using high-density
SNP arrays (BovineHD 770K, OvineSNP50, PorcineSNP60). GWAS identified 47 significant SNP loci (p < 5 x 10-8)
associated with disease resistance phenotypes including somatic cell count (SCC) in cattle, footrot resistance in sheep,
and PRRS viral load in pigs. Candidate gene analysis highlighted GBP5, TLR4, and CD163 as primary immune-effector
genes exhibiting significant expression fold changes (log2FC > 2.1) in resistant versus susceptible phenotypic classes.
Linkage disequilibrium mapping revealed three genomic regions of selective sweep coinciding with major
histocompatibility complex (MHC) class II loci, suggesting long-standing natural selection pressure on adaptive immune
pathways. These findings provide actionable genomic markers for marker-assisted and genomic selection programmes
aimed at breeding disease-resilient livestock populations.