Effects of Fattening Period on Growth Performance, Carcass Characteristics and Lipogenic Gene Expression in Hanwoo Steers

This study was conducted to investigate the effects of different fattening periods i.e. 25, 27 and 29 months of age (25 mo, 27 mo and 29 mo), on feed consumption, body weight gain, carcass parameters, and lipogenic gene expression in 45 Korean native steers (Hanwoo). Daily DM intake was higher in steers on 29 mo compared with those on 25 mo or 27 mo. Daily body weight gain was higher in steers on 25 mo compared with those on 27 mo or 29 mo during fattening and overall experimental periods. Therefore, feed conversion ratio was lower in 25 mo compared with 27 mo or 29 mo during the fattening and whole experimental periods. As expected, slaughter and carcass weights were higher in the order of 29 mo>27 mo>25 mo. Carcass yield grade was relatively lower in 29 mo reflecting higher back fat thickness compared with other treatments, while carcass quality grade was not largely influenced by the treatments. By investigation with an ultra-sound scanning technique, the marbling score was significantly and numerically higher in 25 mo compared with 27 mo or 29 mo. The mRNA levels of stearoyl-CoA desaturase (SCD) gene were gradually increased in the late fattening stages (p<0.01) and mRNA of acetyl-CoA carboxylase (ACC), ATP citrate lyase (ACL) and glucose transporter 4 (GLUT4) gene were highly expressed in 29 mo compared with 25 mo and 27 mo (p<0.05). However, gene expressions of adipocyte fatty acid binding protein 4 (FABP4) and lipoprotein lipase (LPL) were not significantly different among the treatments. Thus the present results indicated that different fattening period has no major effect on carcass characteristics, although 25 mo had a lower carcass weight compared with 27 mo or 29 mo.