RESPONSE TO ELECTRICAL STIMULATION AND POST‐MORTEM CHANGES IN TURKEY PECTORALIS MAJOR MUSCLE

Abstract

SUMMARY– Muscle samples were obtained from 20 turkey hens 5 min postexsanguination for the determination of sarcomere length, response to electrical stimulation, and time‐course of rigor mortis. Additional samples were obtained from the opposite (undisturbed) pectoralis major muscle at 1, 2, 6 and 24 hr post‐mortem for the determination of sarcomere length. Birds were divided into three groups based on the time to complete rigor mortis: (1) slow, > 125 min; (2) fast, <50 min; and (3) intermediate, 50–125 min. Birds that displayed a long time course of rigor mortis had a low threshold of response (9v) and a long duration of response (106 seel to electrical stimulation. Conversely, muscles which become inextensible within 50 min displayed a high threshold (123v) and low duration (8 sec). Muscles with intermediate rates of rigor had intermediate threshold (58v) and duration (50 sec). Increase in sarcomere length occurred within 1 hr post‐mortem in the fast‐rigor group, 2 hr in the intermediate‐rigor group and 6 hr in slow‐rigor birds. A similar experiment conducted on 24 toms indicated that postexsanguination struggling resulted in a decreased time course of rigor, elevated threshold and shortened duration of response to electrical stimulation. Strugglers displayed a more rapid (P<.01) post‐mortem increase in sarcomere length than non‐strugglers. The results suggested that in some presently‐used commercial turkey processes, some of the carcasses are frozen with muscles in a prerigor, short‐sarcomere state.