Acta Technologica Agriculturae 4/2017Radim KUNEŠ et al.The consumption of meat and other animal products has increased in recent decades. Farmers' efforts to meet market demands lead to intensification of livestock production (Gerber et al., 2013;Powers et al., 2005). Thanks to the improvements in breeding technology, a higher number of animals can be housed in the barn at the same time. However, the intensification of livestock production results in increased concentrations of ammonia, odour and dust not only inside the building, where the breed is located, but also in its surroundings, where these undesirable substances are deliberately discharged throughout the ventilation systems (Brouček and Čermák, 2015;Heyden et al., 2015;Janoško and Čery, 2011). Intensive livestock farming is a stationary anthropogenic source of odour substances. Odour primarily burdens the barn environment, where the health of the nursing people and animals is negatively affected. However, areas close to the breeding premises are also significantly influenced. The most risky areas are considered to be within 500 meters from the breeding hall (Héroux et al., 2004). The whole situation is further complicated by the trend of recent years, namely the construction of new rural settlements in close proximity to breeding halls. People inhabiting these houses frequently complain about the intense odour that accompanies their stay near the breeding premises. The higher odour concentration can cause a higher risk of respiratory diseases, mucosal irritations or nausea (McArthur, 1987;Radon et al., 2001).Odour substances are produced mainly by biological degradation of droppings at poultry farms, which take place both under aerobic and anaerobic conditions (Hobbs et al., 2004;Jiang and Sands, 2000;Powers, 2002). The amount of produced droppings depends on the age, weight and health of animals.Droppings accumulated in the deep litter cannot be effectively removed during the breeding batch and their total amount in the breeding hall gragually increases with time. The microclimate conditions inside a barn also change as the animals are growing up and the amount of odour produced is gradually increasing as well (Dunlop et al., 2016;Said et al., 2016;Winkel et al., 2016).The total emission of odour substances produced from intensive broiler breeding depend on many factors, such as building design, ventilation mode, barn microclimate, breeding technology, climatic conditions, the age and number of housed animals, nutrition, concentration and dust particle size, ethological manifestations of animals and many others (Redding, 2013;Pogran et al., 2009; Xin et al., 2011;Jiang and Sands, 2000;Knížatová et al., 2009). The spread of odour to the environment depends, among others, on weather and topographical conditions. The aim of this study was to establish the changes in odour emission in dependence on time continuously throughout the whole fattening process and to determine the basic parameters inside the barn that can affect the overall emission production...