Genetic mechanisms contribute to beef tenderness differences

Beef tenderness is valued by consumers and influenced by both environmental and genetic factors.

Beef tenderness is valued by consumers and influenced by both environmental and genetic factors.
According to research presented during the "late-breaking research" session at JAM 2013 in Indianapolis, Ind., postmortem treatment by electrical stimulation (ES) increases tenderness and reduces, but does not eliminate, variation among carcasses.
Texas A&M researchers R.N. Vaughn, A.K. Torres, K.J. Kochan, R.K. Miller, C.A. Gill, A.D. Herring, D.G. Riley, J.O. Sanders, J.W. Savell, T.H. Welsh and P.K. Riggs said the purpose of their study (abstract LB6) was to examine genetic factors that influence tenderness, particularly in post-ES beef.
Skeletal muscle samples were collected immediately after slaughter from crossbred Nellore-Angus steers. Warner-Bratzler shear force measurements following 14 days of aging were used as an objective measure of tenderness, they reported. Microarray analysis of samples from 48 steers, chosen for divergent response to ES, was used to identify networks of genes with significantly different gene expression between tenderness groups and to identify significantly enriched signaling pathways, Vaughn et al. explained. In addition, single nucleotide polymorphism haplotype blocks encompassing genes of interest were constructed to examine parent and breed of origin effects.
They reported that 40 genes were assayed by real-time polymerase chain reaction. Several genes in the integrin family were upregulated in the group that responded well to ES compared with the group that responded poorly.

Through haplotype analysis, Vaughn et al. found that breed and parent of origin had an effect on tenderness. Breed of origin of the integrin alpha-6 (ITGA6) gene corresponded to a 0.15-kg difference in ES residual tenderness values when inherited maternally (P = 0.03). The gene fibronectin 1 (FN1) had a difference in ES residual tenderness of 0.23 kg for different paternally inherited haplotypes (P < 0.01), the researchers noted. Also, ITGA6 protein expression was closely related to mRNA expression in the subset analyzed by Western blot. 

Vaughn et al. concluded that this approach identified a network and biological mechanism associated with tenderness that has not been previously established. These results also suggest that targeting components of the ECM represents a novel area of research for improving tenderness.

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