The effects of indoor air pollutants on the health and production of growing pigs.
2004
Murphy, T. | Cargill, C.
A range of pollutants such as gases, particulate matter and toxins are present in the airspace of animal houses. Gases include ammonia, carbon dioxide, carbon monoxide and hydrogen sulfide. Particulate matter includes undigested and digested nutrients, skin dander, dried dung and urine and a range of microorganisms. Other chemicals include bacterial and fungal toxins and volatile fatty acids. The main source of airborne pollution is the pigs and their excretions. The key pollutants are ammonia, particulate matter and the microorganisms and their metabolites. The effects of these pollutants on pig health and production will vary depending on the mixture and concentrations of the pollutants present. The key effects include a range of clinical signs and inflammatory and immune responses. Clinical signs include coughing, sneezing, salivation, loss of appetite and excessive lachrymal secretions, as well as depression of growth rate, which is not limited to pigs with respiratory disease. The inflammatory response is both local and general and involves activation of the immune system. Local inflammatory changes include loss of cilia, thickened epithelia and decreased numbers of goblet cells in the trachea and turbinates, along with activation of epithelial cells, alveolar macrophages and polymorphonuclear cells releasing of a variety of inflammatory mediators. Nonspecific activation of the immune system involves the production of cytokines and is thought to divert nutrients away from growth and accretion of skeletal muscle to support the inflammatory and immune responses.
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