SE—Structures and Environment: Ammonia Emission and Nitrogen Balances in Mink Houses

Ammonia emissions from mink houses were measured over two seasons for growing kits in a two-row open-sided building with slurry gutters (385 mm wide). In the first season, a layer of sand was placed below the cages, and in the last season a layer of chopped barley straw on sand, to serve as a collector for urine and faeces dropped outside the gutter. When the slurry was removed weekly in the houses with slurry gutter and sand layer, the ammonia emission was 0·59 g [N] per animal per 24 h at 6°C and 1·15 g [N] per animal per 24 h at 16°C. By covering the ground area below the cages with a layer of chopped barley straw, renewed weekly, the nitrogen loss increased with the time since the latest renewal of the straw. One week after renewal of straw and removal of slurry, the emission amounted to 0·70 g [N] per animal per 24 h at 6°C and 1·44 g [N] per animal per 24 h at 16°C. Nine-week nitrogen balance measurements were carried out in three sections over the second season. When a layer of chopped barley straw on the ground area was renewed once a week, about 45% of the nitrogen in the consumed feed was collected in the slurry gutter by emptying the gutter twice a week. About 19% was collected in straw beneath the cages, about 5% was deposited in the carcass, about 20% evaporated, and the rest, about 11%, was assumed to be collected in the sand layer below the cages.