Characterization of two pro-opiomelanocortin gene variants and their effects on carcass traits in beef cattle

Carcass quantity (lean meat yield) and quality (degree of marbling) in beef cattle determines much of their economic value. Consequently, it is important to study genes that are part of the appetite pathway and that may ultimately affect carcass composition. Pro-opiomelanocortin is a prohormone that codes for many different peptides, several of which are involved in the appetite pathway. A single nucleotide polymorphism (SNP) c.288C>T in pro-opiomelanocortin (POMC) has previously been associated with hot carcass weight (HCW) and shipping weight (Ship wt) in beef cattle.

While developing a commercial real time PCR test for POMC c.288C>T a 12 bp deletion (POMC c.293_304delTTGGGGGCGCGG) was identified. The deletion results in the removal of four amino acids (a valine, two glycines, and an alanine). Both the POMC c.288C>T and the deletion were genotyped in 386 crossbred steers and evaluated for associations with carcass traits. The animals with one copy of the deletion had a significantly smaller carcass rib-eye area (7.91 cm²; P = 0.02) in comparison to homozygous normal animals. Significant associations were observed between POMC c.288C>T with start-of-finishing weight (SOF WT; P = 0.04), hot carcass weight (HCW; P = 0.02), average fat and grade fat (both P = 0.05), carcass rib-eye area (REA; P = 0.03) and marbling (P = 0.02).

These results suggest that it could be beneficial for beef producers to know both the deletion and POMC c.288C>T genotypes when making marketing and culling decisions.