Quantitation of Indole and Skatole in a Housed Swine Unit

Abstract

AbstractWhile many compounds have been identified as odor constituents of animal waste, few have been measured quantitatively and directly implicated as parameters for evaluating the quality or strength of odor. To determine the possibility of contribution to odor, two alkaloids, indole and skatole, were measured quantitatively in fresh manure, in anaerobic pit liquor, in dust, and in air extracts from an enclosed swine‐finishing unit. Gas, thin‐layer, and column chromatography were used to measure the concentrations and to verify the presence of indole and skatole. Although indole and skatole were found in the fresh manure and anaerobic pit liquor extracts, only skatole was found in the dust extracts. Neither indole nor skatole could be detected in the air of the swine unit above the detection limits of 2.5 × 10−12 g/ml of air. Since the odor threshhofd value of indole and skatole (1 × 10−9 g/ml of air) is approximately 1,000 times higher than what could be detected in the air, it was concluded that aerial concentrations of indole and skatole in swine units could not be used to evaluate the quality and strength of odors.