Stress physiology of animals during transport.

Welfare is not totally objective. What level of physiological stress or mortality is acceptable? How hungry or thirsty can an animal become before the conditions are not acceptable? Degrees of hunger, dehydration and other stresses can be measured with objective biochemical methods or other tests. One must remember that during mating, play or hunting, many of the biochemical variables that are commonly used as measures of welfare reach extreme values. In these situations, the animal may have good welfare. However, many stressors that occur during transport have a longer duration. In this chapter, studies on transport mortalities for cattle, calves, sheep, pigs and poultry are reviewed. The chapter also reviews measures of physiological indicators of fasting, dehydration, general reactions to stress (heart rate, cortisol, respiration and glucose) and physical activity (lactate, glycogen, creatine kinase).