Abstract
In poultry processing facilities, bleeding is considered as a major cause of economic loss. Operations are also largely impacted by chicken wing break, which is a term for open dislocation of the elbow joint and dislocation of the shoulder, due to the diminished commercial value of the carcass and the need to partially reshape the meat. The causes of chicken wing break and countermeasures for its prevention were examined using the stunning voltage and ATP-related substances as part of efforts in increasing awareness for animal welfare and measures against economic loss in chicken processing. Stunning voltages were set for different types of chickens, and the optimal stunning voltage for the broiler was determined to be 22V, which was lower than the routine voltage used and was thus strongly associated with chicken wing break. ATP-related substances (i.e., adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, inosinic acid, inosine, and hypoxanthine) in the meat of wing-broken and normal chickens were measured, and the Ka value in the muscle, which was an indicator of the extent of muscle breakdown, was determined. The Ka values of broilers exhibiting chicken wing break and of normal-carcass broilers were 93.5±1.9% and 88.0±3.1%, respectively. The Ka value of carcasses showing bleeding spots under the thigh skin at a stunning voltage of 29V was 90.1±2.3%. This information suggests that an optimum after-stunning voltage is effective in preventing chicken wing break, and that the Ka value is impacted by a strong convulsive reaction, which is associated with joint damage.
Ka＝(IMP+Ino+Hyp)/(ATP+ADP+AMP+IMP+Ino+Hyp).
