Recently, with the increase of meat production, high quality and safety of meat have been strongly emphasized by Korean consumers. Marbling in beef has been regarded as an important criterion deciding meat quality in Korea. The purpose of this study was to identify the transcriptional level of insulin-like growth factor-1 (IGF-1) in longissimus muscle samples of 46 Hanwoo. The level of IGF-1 transcripts was measured by real-time polymerase chain reaction (PCR) and molecular connection of IGF-1 was analyzed using the Pathway Studio program (Ver 9.0). Increase of marbling score (MS) induced increase of IGF-1 transcripts level in the muscle and there is a significant correlation (p<0.05) between IGF-1 mRNA expression and MS. The pathway study showed that IGF-1 genes are regulated in insulin, fatty acid synthase, leptin, and corticotrophin releasing hormone. These results suggest that IGF-1 might be used as a useful marker for the improvement of economic traits in Hanwoo.

The bovine fatty acid binding protein 4 and 5 (FABP4 and 5) is a major positional and physiological candidate gene for the bovine marbling and carcass weight. The aim of this study was to evaluate the association between economic traits of Korean cattle (Hanwoo) and genetic variation in fatty acid binding protein 4 and 5 (FABP4 and 5) genes within carcass/meat quality traits and the before/after of fatting in breed Hanwoo. Here, we characterized the nucleotide polymorphism of FABP4 and 5 in 86 cattle. We were detected the variability of three types (GG, AG, and AA) by PCR, and economic traits were analyzed by the mixed regression model implemented in the ASReml program. As the result of statistical and supersonic analysis, FABP4 gene was highly showed significant effect (p<0.006) on marbling score (MS), in contrast FABP5 gene was lowed (p<0.084) on MS before fatting. But, FABP4 gene was highly showed significant effect (p<0.0054) on MS, in contrast FABP5 gene lowest (p<0.0899) on MS in the after of fatting. Compare to supersonic result before fatting in FABP4 gene, it was detected type GG: (p<7.18), AG: (p<8.50), and AA: (p<10.50) (n=50), showed type GG: (p<4.88), AG: (p<2.33), and AA: (p<0.00) after weed out (n=20). Futhermore, it was detected type GG: (p<9.30), AG: (p<7.95), and AA: (p<7.40) (n=50) before fatting in the FABP5 gene. It was shown type GG: (p<2.67), AG: (p<3.50), and AA: (p<5.00) after weed out (n=50). Our results indicate that FABP4 and 5 gene transcription is regulated by the environment of feeding and management, and suggest that feeding and management could be potential key in determining FABP4 and 5 genes transcription for carcass/meat quality traits in breed Hanwoo.