Ammonia emission and odour thresholds of cattle houses with exercise yards

The trend towards larger moving areas in exercise yards implies more soiled surfaces, which constitute an additional source of ammonia and odour emission. The goal of the first investigation was to quantify ammonia emission from a soiled exercise yard and to define the factors having an influence on this emission. The percentage of excrement and urine produced in a permanently accessible exercise yard without any further occupation facilities for the animals (Brown Swiss) is low. Ammonia is released after a short space of time. Cleaning the yard more frequently has only limited effects as regards reduction of ammonia emission; fresh excrement appears steadily, and the surface is never really clean. Urine is the main source of ammonia emission and should be drained as rapidly as possible from the yard surface. The aim of the second investigation was to determine odour thresholds of cattle houses with exercise yards by field inspections and to assess them in comparison with pure indoor stock keeping. Nine dairy farms using deep litter or cubicle houses and concrete floored exercise yards had been selected for this purpose. At least two inspections per farm were carried out in summer 1996 and winter 1996/97 before and after cleaning the exercise yard. Frequency and intensity of odour was compared. Wind speed had a strong influence on each single measurement.