Rest before slaughter ameliorates pre-slaughter stress-induced increased drip loss but not stress-induced increase in the toughness of pork

One factor affecting meat quality is pre-slaughter stress. We investigated the effects of exercise stress on drip loss and toughness in relation to resting times of 0, 1 or 3 h following exercise on a treadmill. This exercise stress was regarded as combined physical and physiological stress. Exercise stress increased the muscle temperature, reduced the creatine phosphate, ATP and glycogen content of pigs slaughtered immediately after stress exposure. These conditions lead to a reduced pH early post mortem and an increased drip loss, while only 1 h of rest after exercise stress normalised these effects. However, an overshooting effect was noted when pigs were rested for 1–3 h before slaughter, emphasising the importance of critical control of the resting period when studying exercise stress-induced effects on meat quality. Furthermore, meat from exercise stressed pigs, irrespective of resting, had increased toughness compared to controls, indicating that the toughness was not related to drip loss in meat from exercise stressed pigs.