Ventilation, air hygiene and animal health.

The objectives of a ventilation system are to provide an aerial environment in which 1, animals' health and productivity can be maintained, 2, the stockman's comfort and health needs are satisfied, and 3, the building and equipment are protected from damage. Criteria for evaluating ventilation include: thecontrol of air temperature and air speed at animal height, the control of relative humidity and prevention of condensation, and the maintenance of tolerable concentrations of gases, dust, and airborne microorganisms. In practice most ventilation systems use thermal criteria for calculating minimum ventilation rates. Current recommended minimum ventilation rates for livestock buildings are given. Ventilation strategies taking account of temperature, carbon dioxide, relative humidity and risk of condensation are considered.