Relationships Of Muscle Fibre Growth To Meat Quality Traits In Different Broilers

Recessive White Plymouth Rock(RWPR), Beijing-fatty and Beijing-fatty ((?) )× Recessive White Plymouth Rock ((?)) (C) were fed to 14 weeks to investigate the development character of growth, slaughter performance, and muscle fiber. The association between muscle fiber and meat quality was also anlyzed.Recessive White Plymouth Rock (RWPR) grew faster than Cross and Beijing-fatty (BF). At 8 wks of age, body weight (BW) of RWPR amount to 1308.86 g and body weight of Cross is 1030.5g ,while BF only 630.75 g. BW of male chickens were greater (P<0.01) than that of females after 6 wks of age. The dressed BW (90%), percentage of eviscerated carcass (64%) of RWPR at 10 wks of age were greater than those of 14 wks, indicating that RWPR is suitable for slaughter at 10 wks of age. However, BF will get a good slaughter performance at 14 wks of age.The muscle fiber parameters measured by fresh muscle were highly correlated to those by paraffin slice protocol (r=0.92, P<0.01). The diameter increased with age, and the diameter of leg muscle was greater than that of breast muscle by 20% approximately. Results from slice showed that the diameter of muscle fiber of RWPR was greater than that of BF (P<0.01) after 6 wks of age, while the Cross in the between. There was no difference among the diameters of leg or breast muscle fiber at hatch in RWPR, Cross, and BF (P>0.05), while the diameter of leg muscle for RWPR, Cross, and BF (56.93, 49.29, and 42.89um, respectively) differed at 14 weeks of age (P<0.01).The muscle fiber density decreased with age and the density of breast muscle was greater than that of leg muscle by nearly 60-70%. The density of BF (888.55 unit/mm~2) was greater (P<0.01) than that of RWPR (561.89 unit/mm~2) at 14 wks of age, while that of Cross was between RWPR and BF.The diameter of leg and breast muscle fiber was positively correlated to BW, leg and breast muscle weight (r=0.65-0.75, P<0.0001) at 12 wks of age. The diameter was positively associated (r=0.10-0.12) with shear force, suggesting that the thinner the fiber was, the tenderer the muscle was. The density of muscle fiber was negatively correlated to body weight, leg and breast muscle weight (r=-0.6~0.8, P<0.0001respectively), and tenderness (r=-0.2 approximately).