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Dairy cattle housing is a significant source of NH3 and GHG emissions to atmosphere. However, the climate, temperature in particular, and the characteristics of the excreta of the housed cattle, may have a strong influence on the magnitude of such emissions. The objectives were to assess the effects of temperature and excreta characteristics of heifers, dry cows and lactating cows on potential NH3, N2O, CO2 and CH4 emissions. The experiment was conducted using laboratory chambers where constant amounts of urine and faeces were applied to a concrete floor. Potential NH3 and GHG emissions were measured over 120-h following application at 5, 15, 25 and 35 °C. Increasing temperature promoted a significant increase in NH3 emissions. At temperatures ≥15 °C, total NH3 emissions accounted for more than 100% of the urea–N content of the urine for the three dairy cattle types, indicating that other organic N compounds of urine and faeces are an important source of NH3. The cumulative amount of N2O released did not vary significantly with temperature and ranged from 1 to 2% of total N deposited. Cumulative CO2 emissions were ca. 14–58% of total C deposited and the cumulative CH4 emissions were significantly higher at 25 °C than at all other temperatures. It was concluded that increasing temperature from 5 to 35 °C significantly increased potential NH3, CO2 and CH4 emissions but did not significantly influence N2O emissions. Also, the diet supplied to lactating cows led to significantly higher NH3, N2O and CO2 emissions relative to heifers and dry cows. [Copyright &y& Elsevier]

Dairy cattle are usually housed in naturally ventilated houses where removal of excreta is periodically performed. The aim of this controlled study was to compare the effect of two floor designs and three air temperatures (5, 15 and 25 °C) on NH3, N2O, CH4 and CO2 emissions arising from cattle excreta deposition to the floor. Two scale models were built to simulate a level solid floor without urine drainage, and a slatted concrete floor. Following application of a mixture of urine and faeces, these two floor type models were subjected to a constant airflow rate (12.5 exchanges h−1) and gaseous emissions were measured over a 72-h period. Emissions of NH3, N2O, CO2 and CH4 increased significantly with air temperature with both floor type models and emissions of NH3, N2O and CO2 were significantly greater from the solid floor relative to the slatted floor at all temperatures considered. The cumulative NH3 (27–66% of total N applied) and CO2 (<19% of total C applied) emissions were greater from the solid floor than from the slatted floor (by 36% and 44%, respectively). The cumulative N2O (<0.1% of total N applied) and CH4 (<0.4% of total C applied) emissions were relatively low and CH4 values did not differ significantly between treatments. Cumulative greenhouse gas emissions (as CO2-equivalents) increased significantly with temperature but did not differ between the floor types. [ABSTRACT FROM AUTHOR]