EFFECT OF ELECTRICAL STUNNING AMPERAGE AND PERI-MORTEM STRUGGLE ON BROILER BREAST RIGOR DEVELOPMENT AND MEAT QUALITY

Two experiments were conducted to determine the effects of electrical stunning and peri-mortem muscle activity (struggle in and around the t ime of slaughter) on post-mortem biochemical reactions in broiler brea st muscle (Pectoralis major). Broilers were stunned with either 50 or 125 mA or were killed without stunning. In Experiment 1 (n = 273), bro ilers were either physically restrained to reduce struggling during sl aughter or were unrestrained and allowed to struggle freely. Breast me at pH and R-value (ratio of adenosine to inosine nucleotides) were det ermined at 15 min and 24 h postmortem, and Allo-Kramer shear was deter mined on 48 h post-mortem cooked meat samples from muscles excised at 15 min or 24 h. Ln Experiment 2 (n = 65), the breast muscle was unilat erally denervated by surgically severing the Pectoralis nerve on one s ide and performing a sham operation on the contralateral side. Results indicated that physical restraint resulted in higher muscle pH and lo wer R-values at 15 min post-mortem in the unstunned birds and birds st unned at 50 mA, but had no effect on breast meat from birds stunned at 125 mA. There were no treatment effects on meat tenderness or 24-h po st-mortem pH or R-values. Stunning amperage had no effect on denervate d muscle pH at 15 min post-mortem but did affect the sham-operated mus cle pH and R-values as in Experiment 1, These results indicate that th e main effect of electrical stunning on early rigor development may be due primarily to inhibition of peri-mortem struggle.