BIOCHEMICAL-IDENTIFICATION AND BIOLOGICAL ORIGIN OF KEY ODOR COMPONENTS IN LIVESTOCK WASTE

Animal production results in conversion of feeds into valuable product s such as meat, milk, eggs, and wool as well as into unavoidable and l ess desirable waste products. Intensification of animal numbers and in creasing urbanization has resulted in considerable attention to odorou s gases produced from animal wastes. It is clear that animal manure wa s, and still is, a valuable resource. However, it may be a major obsta cle to future development of the animal industry if its impact on the environment is not properly controlled. Poor odor prevention and contr ol from animal wastes is related to a lack of knowledge of the fundame ntal nature of odor and its production by farm animals. Odor, like noi se, is a nuisance or disturbance and there is no universally accepted definition of an objectionable odor. Thus, regulation and control of o dors in the environment is difficult because of the technical difficul ties of defining odor limits and their measurement and evaluation. A v ariety of direct (sensory) and indirect (analytical instruments) metho ds for measuring odor intensity and determination of individual or key odor components are discussed. The biological origins of the four pri ncipal classes of odor compounds, namely branched-and straight-chain V FA, ammonia and volatile amines, indoles and phenols, and the volatile sulfur-containing compounds, are reviewed. Because more than 50% of N from animals is excreted as urea, one strategy to conserve N in waste is to inhibit the urease enzyme that converts urea to ammonia. Labora tory studies to evaluate di-and triamide compounds to control urea hyd rolysis in slurries of cattle and swine wastes are presented. Finally, a brief overview of various intervention strategies is provided. Mult iple combinations of nutritional management, housing systems, treatmen t options as well as storage and disposal of animal wastes will be req uired to reduce environmental pollution and provide for long-term sust ainable growth.