A REVIEW OF THE CONTROL OF ODOR NUISANCE FROM LIVESTOCK BUILDINGS .3. PROPERTIES OF THE ODOROUS SUBSTANCES WHICH HAVE BEEN IDENTIFIED IN LIVESTOCK WASTES OR IN THE AIR AROUND THEM

The literature on the odorous compounds identified in livestock wastes or in the air around them has been reviewed, and the resulting information on the properties of these compounds is presented in a series of tables. The total number of compounds which have been identified is 168, of which 30 have odour detection thresholds lower than or equal to 0·001 mg m-3. Six of the ten compounds with the lowest odour detection thresholds of all contained sulphur. The odour detection thresholds of several of the compounds which have been identified in livestock wastes are still unknown, but the chemical structure of some of these compounds suggests that they may be powerful odorants. The information available in the literature is concerned predominantly with odour concentration (in terms of detection threshold) of single compounds; information on mixtures or on odour offensiveness is still very scarce. Odours from livestock buildings may change in both concentration and offensiveness, as a result of natural chemical or biochemical processes, as a sequence is followed from the waste itself, via its immediate vicinity and the building air in general, to the air exhausted from the building. Many authors have made insufficient distinction between the stages in this sequence. It is therefore recommended that systematic experiments be mounted to sample all locations in the sequence, at several different types of livestock building. © 1992 Silsoe Research Institute.