The effects of stress on cattle, pigs and sheep prior to slaughter are reviewed. Long-term preslaughter stress, such as fighting, cold weather, fasting and transit, which occurs 12 to 48 hours prior to slaughter depletes muscle glycogen, resulting in meat which has a higher pH, darker color, and is drier. Short-term acute stress, such as excitement or fighting immediately prior to slaughter, produced lactic acid from the breakdown of glycogen. This results in meat which has a lower pH, lighter color, reduced water binding capacity, and is possibly tougher. Psychological stressors, such as excitement and fighting, will often have a more detrimental effect on meat quality than physical stressors, such as fasting or cold weather. Fighting caused by mixing strange animals together is a major cause of dark cutters in cattle and deaths in stress susceptible pigs. The physiology, causes and prevention of the porcine stress syndrome and dark cutters, is reviewed. Methods for detecting genetically stress susceptible breeding stock are reviewed. The effects of stunning method on meat quality are also covered.
Grandin, T. (1980). The effect of stress on livestock and meat quality prior to and during slaughter. International Journal for the Study of Animal Problems, 1(5), 313-337.