Pereira, José LuísFerreira, SílviaGarcia, CarlaConde, AndréFerreira, PedroPinheiro, VictorTrindade, Henrique2018-08-312018-08-312017-12-01Pereira, J.L.S., Ferreira, S., Garcia, C.S.P., Conde, A., Ferreira, P., Pinheiro, V., & Trindade, H. ( 2017). Assessment of ammonia and carbon dioxide concentrations in a breeding hen building under Portuguese winter. International Journal of Food and Biosystems Engineering, 5, 1-6.2408-0675http://hdl.handle.net/10400.19/5067Excessive ammonia (NH3) and carbon dioxide (CO2) in the housing of breeding hens can cause various negative effects on the health of hens and the welfare of the workers who care for them. The aim of this study was to evaluate the NH3 and CO2 concentrations in the first month of housing the breeding hens during Portuguese winter. The study was conducted on a commercial hen breeding farm located in central Portugal. One modern building equipped with climate control system, automatic feeding and drinking systems and minimum transitional tunnel ridge system was selected. New litter material made with rice hulls was used in the building, and the breeding sample comprised five months old 6864 female and 720 male birds housed in the building on 7 November 2016. The outdoor and indoor environmental conditions and indoor gas concentrations were measured continuously from 10 November to 30 November 2016. (NH3)and CO2 concentrations were measured with a photoacoustic field gas monitor and air samples collected through 4 sampling points located indoor, by a multipoint sampler. Results showed that the CO2 concentrations did not exceed 3000 ppm during the first month of housing the breeding hens and under winter environment. However, the NH3 concentrations exceed 20 ppm on most measurement days. For a good indoor air quality, the study suggests the use of mitigating measures for maintaining NH3 concentration below 10 ppm.engBreeding hensCO2Gas concentrationPoultry husbandryNH3Winter environmentjournal article