Abstract. Greenhouse gas (GHG) and ammonia emissions are important environmental impacts from meat chicken houses. This study measured ammonia (NH 3 ), nitrous oxide (N 2 O) and methane (CH 4 ) in two trials from paired, commercial meat chicken houses using standard (control) and mitigation strategies. In Trial 1, emissions from houses with standard litter depth of 47 mm (LD 47 ) or increased litter depth of 67 mm (LD 67 ) were compared. When standardised to a 42-day-old bird, emissions were 11.9 g NH 3 /bird, 0.30 g N 2 O/bird and 0.16 g CH 4 /bird from the LD 47 and 11.7 g NH 3 /bird, 0.69 g N 2 O/bird and 0.12 g CH 4 /bird from the LD 67 . Emissions per kilogram of manure N were 0.14 and 0.11 for NH 3 -N, 0.003 and 0.005 N 2 O-N and CH 4 conversion factors were 0.08% and 0.05%. Total direct and indirect GHG emissions reported in carbon dioxide equivalents were found to be higher in LD 67 in response to the elevated direct N 2 O emissions. Trial 2 compared the impact of reduced crude protein (CP 19.8 ) and a standard diet (CP 21.3 ) developed using least-cost ration formulation, on emissions. Emissions per bird for the CP 19.8 diet were 7.7 g NH 3 /bird, 0.39 g N 2 O/bird and 0.14 g CH 4 /bird, while emissions from birds fed the CP 21.3 diet were 10.6 g NH 3 /bird, 0.42 g N 2 O/bird and 0.19 g CH 4 /bird. Significant differences were observed only in the NH 3 results, where emissions were reduced by 27% for the low-CP diet. Because of the low emission levels, total mitigation potential from indirect GHG emissions was relatively small in Trial 2, corresponding to 11 t carbon dioxide equivalents/year per million birds.