How Pigs Influence Indoor Air Properties in Intensive Farming: Practical Implications – A Review

Indoor environmental conditions in intensive pig farms are influenced by both the outdoor air temperature and humidity, and the heat, moisture and gas exchanges between the animal and the air. As ventilation rate in pig facilities is usually estimated in temperature, moisture and even CO₂ balances, estimation of heat losses or gains, and moisture and CO₂ production from the animal is needed, but the contribution of other sources of the barn, such as slurry or wet surfaces have also to be taken into account. Some recent studies have been conducted to update total heat and moisture production at farm level, showing that current, historical standards of latent heat transfer are consistently lower than those reported recently at facility level, for both adult and growing animals. Also, CO₂ production needs to be updated by including an estimation of its release from slurry. These new values will help with updating the standards for ventilation rate recommendations and design of the modern intensive pig buildings.