PSV-31 Mechanisms and biochemical pathways affecting the eating quality of Triceps brachii muscle

Abstract Twenty-four beef steers (Angus, Charolais and Angus crossbred) were used to test the hypothesis that phenotypic measurements of meat quality attributes and intramuscular connective tissue characteristics will be related to the differences in the expression level of genes involved in the synthesis and degradation of collagen. Triceps brachii muscles from steers with low and high intramuscular collagen solubility at 3 days post mortem (dpm) were selected within each breed type for candidate gene analysis. Expression levels of 27 candidate genes were evaluated using quantitative real-time polymerase chain reaction (RT-qPCR) and the mean differences in expression between candidate and control (18s RNA) genes were calculated. Analysis of variance indicated that breed type had significant effects (P < 0.05) on expression of genes related to collagen types I, V, and VI (COL1A1, COL5A1 and COL6A1), fibroblast growth factor (FGF), lysyl hydroxylase (LH), matrix metalloproteinases (MMP) 1, 8 and 13, prolyl 4-hydroxylase (P4HA1), SMAD (2, 3 and 7), and tissue inhibitor of MMPs (TIMP). Collagen heat solubility had no effect on gene expression (P > 0.05), although there was a significant interaction between breed type and collagen solubility (P < 0.05) for COL3A1, FGF2, MMP13, and SMAD 6 expressions. Candidate gene expression levels were correlated to intramuscular pH, 3 and 13 dpm Warner-Bratzler shear force (WBSF), total intramuscular collagen, and collagen heat solubility at 3 and 13 dpm. Negative correlations (P < 0.05) existed between FGF1 and 13 dpm soluble collagen (r = -0.44), MMP8 and total collagen (r = -0.55) and MMP13 and wet perimysium weight (r = -0.46). Positive correlations (P < 0.05) existed between FGF1 and 3dpm WBSF (r = 0.44) and, TIMP3 and 3 dpm WBSF (r = 0.33). Results indicated genes associated with increased collagen synthesis and inhibition of MMPs were related to increased beef toughness.