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Emission of NH₃ from dairy barns can be reduced substantially by changing the cows’ diet. Emission of NH₃ is reduced most effectively when dietary changes result in a reduction of urinary urea concentration. The objective of this research was to predict NH₃ emission from dairy barns for various diets, using feed characteristics, and climate, barn, and slurry related parameters. Model results were validated using experimental data. Cows were fed one of nine diets, which was a combination of three rumen degradable protein balances and one of three roughage compositions. Each diet was repeated once. Measured parameters included herd, diet, urine, slurry, barn and climate characteristics, and emission of NH₃ from the barn. For a wide range of diets and barn conditions, observed NH₃ emission from a dairy barn can be predicted accurately using a combination of existing nutrition-emission models. Accuracy of …