The impact of dairy cow and pig housing systems on ammonia emission rates was studied under production conditions. During research the inside and outside air temperature, relative humidity, CO₂ concentration in the inside and outside air and NH₃ concentrations in the inside air and under the slats were measured. ALMEMO, Drager Pac III, and GasProbe IAQ measuring instruments were used. From the measurement data ventilation rates and ammonia emission rates were calculated. During the housing period, the NH₃ emission per animal stall in an the insulated cowshed with tied cows and in a cowshed with partly slatted floor was the same at approximately 29 g per day. In an uninsulated cowshed it was less at 17 g per day. Ammonia emission during a 220-d housing period per animal stall in an uninsulated cowshed was 3.7 kg, and in an insulated shed it was 6.4 kg. The lowest emission (2.2 kg per pig per year) was achieved by keeping pigs on abundant straw litter, changed every week. With a slatted floor system, the annual ammonia emission rate was 2.5 kg per pig.