Effect of electrical stunning current and frequency on meat quality, plasma parameters, and glycolytic potential in broilers

This study was designed to determine the effect of electrical stunning variables (low currents and high frequencies) on meat quality, glycolytic potential, and blood parameters in broilers. A total of 54 broilers were stunned with 9 electrical stunning methods for 18 s using sinusoidal alternating currents combining 3 current levels (35 V, 47 mA; 50 V, 67 mA; and 65 V, 86 mA) with 3 frequencies (160, 400, and 1,000 Hz). Samples for meat quality were obtained from the pectoralis major (PM) and musculus iliofibularis (MI), and samples for glycogen metabolism were taken from the PM and tibialis anterior muscle at 45 min postmortem. The use of high frequency reduced the shear value in PM (400 and 1,000 Hz vs. 160 Hz; P < 0.01) and cooking loss in MI (1,000 Hz vs. 160 and 400 Hz; P < 0.01). The shear value of PM decreased at high frequency (400 and 1,000 Hz) when current was high (50 V, 67 mA and 65 V, 86 mA; P < 0.01) but increased at high frequency (1,000 Hz) when current was low (35 V, 47 mA). Stunning with 1,000 Hz (vs. 160 Hz) caused low glycogen and glycolytic potential in PM (P < 0.05). Plasma corticosterone decreased (P < 0.05) at high currents (>= 50 V, 67 mA) but was not affected by changes in frequency. Electrical current interacted with frequency in plasma glucose, redness 24 h postmortem, shear value (PM), pH 24 h postmortem (MI), and glycolytic potential (tibialis anterior; P < 0.05). This study indicated that high stunning frequencies (400 and 1,000 Hz) may improve meat quality without aggregating stress when the current was not too low (>50 V, 67 mA).