A COLD SHORTENING EFFECT IN AVIAN MUSCLE

SUMMARY— Experiments were conducted to determine the effect of post‐mortem temperatures between 0 and 20°C on the degree of shortening in isolated pectoralis major muscles of chickens and turkeys. A “cold shortening” effect in these muscles is described and compared to post‐mortem pH, average sarcomere length of isolated myofibrils, and relative solubility of myofibrillar and sarcoplasmic proteins. The degree of muscle shortening at each temperature after various periods post‐mortem indicated that shortening was essentially complete after 3 hr in chickens and 5 hr in turkeys. Shortening in muscles stored at 0°C was significantly greater (P < .01) than in the 12–18°C temperature range. Shortening was greatest in muscles stored at 20°C. The degree of gross shortening observed was directly related to the average sarcomere length of isolated myofibrils. Post‐mortem decline in pH was not significantly correlated (P > .05) with shortening. Extractability of myofibrillar and sarcoplasmic proteins after 5 hr at either 0 or 16°C was determined and found to be unrelated to the degree of post‐mortem shortening. Copyright © 1969, Wiley Blackwell. All rights reserved