Pre-slaughter fasting is a very important practice in themeat industry. The present study was designed to investigate
the effect of fasting on energy metabolism and tenderizing enzymes in chicken muscle early postmortem.
A total of 30 Yellow-feathered chickens were deprived of feed for 0 h, 12 h and 24 h before slaughter (n=10
each group). Breastmuscles were removed and cut into 3 parts and stored at 0 °C for 0 h, 3 h and 10 h. Samples
were used for analyses of zymography, cathepsins, pH, glycogen/ATP/ADP/AMP, hormones and ultrastructure.
Fasting caused the accelerated depletion (pb0.05) of glycogen, ATP and ADP before or immediately after slaughter,
but no difference existed in ATP at 3 and 10 h (p>0.05). Fasting resulted in greater ultimate pH (pb0.05).
Zymography indicated that fasting delayed the activation of μ/m-calpain (pb0.05), however, it accelerated the
release of lysosomal enzymes (pb0.05). Fasting for 24 h resulted in greater ultrastructural changes and plasma
corticosterone levels than fasting for 12 h and control groups. Therefore, fasting for no more than 12 h is acceptable
in practice.