Knížatová M. author Mihina Š. author Brouček J. author Karandušovská I. author Mačuhová J. author text journal article 2010 The research reported in this article attempts to address the ammonia problem by quantifying the effect of several variables on ammonia concentrations and emissions. These variables include litter temperature, litter age and ventilation rate. Data was collected in a commercial tunnel-ventilated grow-out facility with deep litter, designed for 25 000 broilers, during 6 consecutive flocks. Birds were housed from hatching to approximately 40 days of age. Litter temperature and litter age were positively correlated (P < 0.0001) with the production of ammonia gas. The amount of ammonia emissions increased with the litter age (P < 0.0001) as a consequence of both the increased ammonia concentration and the ventilation rate (P < 0.0001). The lowest concentrations of NH3 were observed in a "summer" period, although ammonia emissions tended to be higher just in summer months because of a higher ventilation rate. The elevated levels of ammonia in winter were attributed to the lower ventilation rate during cold weather. After the evaluation of ammonia emissions it can be concluded that during the grow-out period of broilers kept on renewed litter there is an average loss of 6.18 g ammonia per bird and/or 0.043 kg of ammonia per bird yearly. The increase in litter temperature during grow-out periods is a process which could be controlled to prevent excessive ammonia volatilization from housing facilities. ammonia; litter; broiler chickens; grow-out period; ventilation rate 10.17221/176/2009-CJAS https://cjas.agriculturejournals.cz/artkey/cjs-201008-0005.php https://cjas.agriculturejournals.cz/artkey/cjs-201008-0005.php continuing 55 8 337 345 2010 12121819 periodical academic journal