Assessing Stress in Farm Animals

The prevention of poor welfare in the animals that we use is one of our moral obligations. Systems for producing farm animals are not sustainable unless people accept the system and its effects and one of the criteria for this is the welfare of the animals. The welfare of an animal is its state as regards its attempts to cope with its environment. In order that welfare can be good, the needs of the animal have to be met and the coping systems help to ensure this. When environmental effects on an animal overtax its control systems and result in adverse consequences, eventually reduced fitness, the individual is stressed. Measures of poor welfare include those that are physiological, some being associated with behavioural and pathological changes. Heart-rate and plasma glucose give information about short-term changes. Hormones, proteins and metabolites in the blood also allow the assessment of the extent of poor welfare, for example during handling and transport. Somewhat longer periods of poor welfare may be identified by measuring behaviour or faecal cortisol. The concentration of oxytocin can sometimes be used as a physiological measure of good welfare. When welfare studies are carried out, it is important that the scientific assessment is considered separately from the ethical judgement.