How can stress before slaughter affect meat quality?

Stress experienced by animals before slaughter triggers biochemical changes in muscle tissue that can significantly degrade meat quality. These effects are primarily linked to how stress influences the postmortem pH levels of the muscle.123

Two primary quality issues arise from preslaughter stress:

• PSE Meat: Pale, soft, and exudative (PSE) meat occurs when there is a rapid postmortem pH decline while muscle temperature remains high. This damages muscle proteins, reducing their water-holding capacity and resulting in soft, mushy, and pale-colored meat.4
• DFD Meat: Dark, firm, and dry (DFD) meat results from extreme stress or physical exertion before slaughter. This depletes the animal's glycogen reserves, preventing the normal accumulation of lactic acid postmortem. Consequently, the meat maintains a higher ultimate pH (6.2–6.5), leading to a dark color and dry appearance that reduces consumer appeal.3

Ethical handling is essential, as minimizing stress through proper ventilation, avoiding overcrowding, and preventing the mixing of animal groups is vital for maintaining meat quality and ensuring humane treatment.56