Effect of stresses before slaughter on changes to the physiological, biochemical and physical characteristics of duck muscle

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Abstract
1. This experiment was designed to study the effects of fasting and enforced exercise on the physiological, biochemical and physical characteristics of duck muscle. 2. Sixty 75‐d‐old male ducks weighing 3.0 ± 0.2 kg were assigned to three treatments: a control, and an 8 and 24 h fast plus enforced exercise for 10 min. The ducks were then sacrificed and the carcass stored at 4°C for 24 h. 3. Although the pH and serum lactate contents gradually increased with fasting time the responses were not significant. The ultimate pH was elevated and the lactate of breast and thigh muscles was lower in stressed birds. 4. The activity of lactic dehydrogenase was significantly increased by the stress, and the activities of creatine phosphokinase and alkaline phosphatase were also increased slightly. However, no effect was found on the ATPase activity of the myofibrillar protein of either breast or thigh muscle as a result of the stress. The ATPase activity of myofibrillar protein of breast muscle significantly increased with storage time. 5. The extractability of myofibrillar protein increased with storage time for all treatments. The SDS‐PAGE patterns of myofibrillar proteins were also studied. 6. Consequently DFD‐like muscle was observed in the breast and thigh muscles of ducks which had been stressed.