Thigh Muscle Response of Broilers to Cold Stress in Comparison to Breast Muscle

摘要

The objective of this study was to assess the effect of acute cold exposure on broiler physiology, breast and thigh muscle metabolites, and meat quality. One hundred sixty male birds at ages of 5 and 6 wk were exposed to temperatures of -9 to -15°C, and +20°C (control) in a simulated transport chamber for 3 h followed by 0 or 2 h of lairage prior to slaughter. Core body temperature was monitored every minute using i-Button data loggers, and live shrink and blood glucose were assessed. Total glucose and lactate concentrations at 30 h post-mortem, as well as ultimate pH (pH_u), color, and water holding attributes were evaluated on Pectoralis major muscle of breast and Iliotibialis muscle of thigh. A significant (P < 0.05) drop in body terriperature and blood glucose and a substantial increase in live shrink were observed at temperatures below 0°C. Following cold exposure, thigh muscle was almost depleted of glycogen compared to a small but significant reduction in breast muscle glycogen when exposure temperature was below -8°C. Similarly much greater effects of simulated cold transport were observed on thigh pH_u, and quality attributes compared to breast. In addition, 84% incidence of the dark, firm, dry (DFD) quality defect was observed for thigh (pH_u > 6.4, L~* < 44) compared to 42% incidence of DFD for breast (pH_u > 6.1, L~* < 46) when transportation temperature was below 0°C. Results of this study showed that thigh muscle was affected more severely than breast muscle by exposure of broilers to cold temperatures prior to slaughter.