Functional analysis of muscle gene expression profiles associated with tenderness and intramuscular fat content in pork

Warner-Bratzler shear force (WBSF) and % intramuscular fat content (IMF) are objective meat quality measurements that are significantly correlated with aspects of palatability such as tenderness, flavour and juiciness. Using cDNA microarrays, Musculus longissimus transcriptomic profiles at slaughter were compared in samples displaying lower or higher IMF (n = 8) and WBSF values on day 1 post mortem (n = 8). 101 identified genes were differentially expressed in relation to WBSF, while 160 genes were associated with differences in IMF. Reduced expression of protein synthesis genes and enhanced expression of genes involved in protein degradation were associated with lower WBSF values on day 1. Pathways including oxidative phosphorylation and the citrate cycle were significantly associated with higher IMF. Many lipid oxidation and fatty acid metabolism pathway genes were down-regulated in high IMF tissue, suggesting a suppression of fatty acid turnover in muscle with higher fat content. Identified genes provide targets for the discovery of novel genetic variation influential on pork palatability.

► Microarray analysis of pig muscle divergent in tenderness and IMF% was carried out. ► Signalling pathways may be more important than metabolic for tenderness. ► Proteasome pathways may be important for pork tenderness and early tenderisation. ► Fatty acid turnover was suppressed, and deposition increased, in higher IMF muscle. ► A repression of carbohydrate metabolism was also observed in higher IMF muscle.