RESUMEN
The aim of this study was to compare the growth performance, fiber characteristics of the pectoralis major muscle, and meat quality characteristics in the heavy weight (HW) and random bred control (RBC) quail lines and genders. The HW male exhibited more than two times greater body (245.7 vs 96.1 g, p<0.05) and pectoralis major muscle (PMW; 37.1 vs 11.1 g, p<0.05) weights compared to the RBC female. This growth performance in the HW line was associated with a greater muscle fiber area (1,502 vs 663.0 µm(2), p<0.001) compared to the RBC line. Greater muscle mass of the HW male was accompanied by a higher percentage of type IIB fiber compared to the HW female (64.0% vs 51.0%, p<0.05). However, muscle fiber hyperplasia (increase in fiber number) has had a somewhat limited effect on PMW between the two lines. On the other hand, the HW line harboring a higher proportion of type IIB fiber showed rapid pH decline at the early postmortem period (6.23 vs 6.41, p<0.05) and lighter meat surface (53.5 vs 47.3, p<0.05) compared to the RBC line harboring a lower proportion of type IIB fiber. There were no significant differences observed in the measurement of water-holding capacity including drip loss (2.74% vs 3.07%, p>0.05) and cooking loss (21.9% vs 20.4%, p>0.05) between the HW and RBC lines. Therefore, the HW quail line developed by selection from the RBC quail, was slightly different in the meat quality characteristics compared to the RBC line, and a marked difference was found in growth performance between the two quail lines.
RESUMEN
The objective of this study was to compare the temporal expression of myosin heavy chain (MyHC) isoforms, Pax7, and myogenic regulatory factors (MRF) between heavy weight (HW) and random bred control (RBC) Japanese quail lines during muscle development to better understand the mechanisms leading to increased skeletal muscle mass in the HW quail line selected for a greater BW at 4 wk of age separated from RBC quail. Expression of neonatal MyHC isoform began at 3 and 7 d posthatch in RBC and HW quail lines, respectively. In the RBC quail line, adult MyHC isoform, as a marker for muscle maturation, was expressed at 28 d posthatch with sustained expression through 75 d posthatch, whereas this protein was detected only at 75 d posthatch in the HW quail line. Moreover, Pax7 expression continued from embryonic ages to 14 d posthatch in the HW quail line and to 7 d posthatch in the RBC quail line. These expression patterns of MyHC isoforms and Pax7 in the HW quail line were accompanied by delayed muscle maturation and prolonged growth compared with the RBC quail line. Temporal expressions of the primary MRF showed that higher expression levels of MyoD and Myf-5 were observed at 9 and 11 d embryo in the HW quail line compared with the RBC quail line (P < 0.05). The HW quail line exhibited approximately 2 times greater average levels of myogenin expression from 7 to 75 d posthatch (P < 0.05) than the RBC quail line. Prolonged upregulation of these primary and secondary MRF during muscle development is associated with delayed maturation and continued muscle growth, which consequently would permit muscle hypertrophic potentials in the HW quail line compared with the RBC quail line.
