Increasingly emissions from livestock production has caused problems for the industry. If the problem can be reduced at source by a change of diet this could be the simplest solution, requiring the minimum of effort.

Reducing nitrogen excretion by pigs offered low crude protein (CP) diets may not only reduce nitrogen polluting potential of slurry, but also change gaseous and odorous emission characteristics.

Slurry was collected from beneath slatted pens at the end of the fmishing period (65 to 90 kg live weight) of groups of pigs offered either a commercially available finisher diet (F-com), slurry A, or a low CP diet (F-lc) formulated using a commercial least cost database which has been shown to reduce the nitrogen concentration of the slurry, slurry B. Slurry samples were placed in a closed odour emission chamber and air samples taken after 0, 15, 40, 65, 95, 155 and 225 minutes. Odour concentration (OC) was determined by dynamic dilution olfactometry.