Abstract: Quebracho tannins are effective for the treatment of animal wastes which contain feces or fecal waste-containing material to inhibit odor emissions therefrom. Application of an effective amount of Quebracho tannins to the animal wastes elicits one or both of reducing gas emissions (such as total gas, hydrogen sulfide, and/or methane) therefrom, and reducing the populations or metabolic activity of anaerobic sulfate reducing bacteria therein. Reduction of odor emissions from the animal waste may also be effected by combining the Quebracho tannins with animal litter which is applied in the locus or vicinity of the animal.