Evaluation of single nucleotide polymorphisms on 3 candidate genes in a population of forage-tested yearling bulls

The objective of the current study was to evaluate the association of single nucleotide polymorphisms (SNP) on 3 candidate genes for growth and performance traits in bulls participating in a forage-based performance bull test. Single nucleotide polymorphisms on 3 candidate genes including calpastatin (CAST), growth hormone (GH1), and IGF-1 were used for association analysis. These SNP were genotyped on 47 purebred Angus, Braford, and Brahman bulls on a forage-based performance bull test. The measured traits included ADG, birth weight, d-0 test weight, 112-d weight, hip height, marbling, rib-eye area, and scrotal circumference. Single nucleotide polymorphism associations were reported as significant if P < 0.05 and were observed on the IGF-1 and CAST genes for growth and production traits. A total of 10 unique SNP (rs109022910, rs109199979, rs109327701, rs132665612, rs132951819, rs136875549, rs136939207, rs137140434, rs137601357, and rs137651874) located on both the IGF-1 and GH1 genes were associated (P < 0.05) with growth and performance traits. Furthermore, of the 12 unique SNP associated with growth and performance, 7 of the identified SNP (rs109022910, rs109199979, rs132951819, rs136875549, rs136939207, rs137601357, and rs137651874) were significantly associated with more than one growth or performance trait. However, the only gene with SNP significantly associated (P < 0.05) with carcass traits was the GH1 gene in which a single SNP (rs137651874) was associated with rib-eye area. Although multiple SNP were associated with evaluated traits, these SNP must be validated in larger and more diverse populations before implementation into selection strategies.