In Holland analysis by Wageningen University & Research of 11000 dairy farms has shown that the crude protein content of grass silage in dairy cows their ration largely determines the level of ammonia emissions. On the ten percent of farms with the lowest crude protein content in grass silage this was 142 grams of crude protein per kilogram of dry matter. On the ten percent of farms with the highest crude protein content in grass silage this was 178 grams of crude protein per kilogram of dry matter. On the ten percent of farms with the lowest crude protein content in grass silage, ammonia emissions from barns and manure storage averaged 8.5 kilograms of ammonia per livestock unit. On the ten percent of farms with the highest crude protein content ammonia emissions averaged 12.9 kilograms per livestock unit.