Assessment of welfare in pigs

According to the definition given by Appleby (1996), animal welfare represents the state of well-being brought about by meeting the physical, environmental, nutritional, behavioural and social needs of the animal or groups of animals under the care, supervision or influence of people. Suitable husbandry techniques and disease control (in which man is directly involved) may satisfy an animal’s physical, environmental and nutritive needs. However, it cannot be stated that people’s supervision or influence always guarantee the satisfaction of behavioural and social needs. Thus, special attention must be paid to these factors in intensive husbandry. This paper calls attention to the main factors characterizing pig welfare on the basis of productive, physiological, pathological and behavioural indicators; to the behavioural needs, which are characterised by several peculiar traits (it is noteworthy that, since the beginning, all categories of reared pigs have been involved in welfare legislation); to all categories of pigs that often show the effects of negative stimuli on their behaviour (limitations, variations); to the main critical points on the farm likely to cause welfare impairment or stress including buildings, inner facilities, space allowance, microclimate, lighting systems, environmental stressors, feeding management, mutilations, weaning, social factors, and stockmanship; and to environmental stressors including dust, odours (especially ammonia) and noises. This paper takes into account sources, effects and possible solutions for noises; the positive effect of fibrous feeding; environmental enrichment and other possible techniques for improving social status and for preventing/reducing stereotypic behaviour and abnormal reactions (e.g. tail biting). The scientific/objective evaluation of welfare for intensively reared pigs may be carried out by means of direct observation of the animals themselves (animal-based or encompassing performance or output criteria), as well as through examinations of a structural nature (design or resource-based, or derived from engineering or input criteria). Preference should be given to the former since they are can be better adapted to the different pig categories and management systems. Design criteria, on the other hand, are easier to evaluate and they should integrate animal criteria. Thus, the most correct protocols for on-farm evaluation of pig welfare should involve both animal-based criteria and design criteria. Examples of both criteria are reported herein. In extensive farming which includes (although somewhat improperly) outdoor and organic farming, achieving a good level of welfare is one of the declared objectives. However, there are several causes of welfare impairment that can be successfully overcome only if highly professional workers are employed: unfavourable climate, parasitic diseases, intake of plants containing poisons or anti-nutritional factors, high piglet mortality.