The effects of the environment on the health and welfare of growing pigs

The welfare of pigs reared in intensive housing systems has been an increasing source of public concern. An investigation was carried out to find factors within the physical and social environment that mediate a range of behavioural and physiological indicators of welfare of growing pigs kept under commercial conditions. An initial study investigated human approach behaviour and clinical signs of disease on commercial farms. Multivariate statistical analysis identified factors that were significantly associated with these welfare indicators, particularly stockman-animal interactions, type of flooring, provision of straw bedding and air quality. This study suggested that the period immediately post-weaning may be important in behavioural development. An abattoir study looked at response to handling, behaviour in lairage, prevalence of bursitis and the prevalence of gastric ulcers post-slaughter. The results indicated the benefits of the provision of straw bedding and welfare problems of slatted flooring, supporting previous findings of a relationship between pelleted diets and increased prevalence of pars oesophageal hyperkeratosis and ulceration. The second abattoir study concentrated on pathological signs of respiratory disease and measurement of acute phase proteins. Only haptoglobin was significantly associated with signs of enzootic pneumonia at slaughter. However, models were successfully constructed for the respiratory diseases and the acute phase proteins that indicated the importance of air quality and some husbandry techniques. Two controlled experiments were carried out, one examining the importance of environmental enrichment at particular rearing stages, the other looking at the effects of alarm pheromones on piglet behaviour. The first trial demonstrated that regularly providing 0.5 kg of straw during rearing only had little effect on welfare and did not affect immune response or adrenocortical function. The second trial demonstrated that pheromones present in the urine of gilts subjected to an alarming situation were aversive to weaner piglets and could have consequences for their welfare