Quantification of Odorants in Animal Feeds at Commercial Swine and Poultry Operations

Abstract

Abstract. Odorants in animal feeds may come from various processes, such as fermentation and decay of feed ingredients, contamination by fecal materials, and sorption of volatiles in the air of animal houses. Those odorants may affect feed flavor and may serve as indicators of feed quality. The objective of this study was to examine the composition and concentration of odorants in animal feeds and to explore the variability of those odorants with animal operation type and season. Thirty-seven feed samples were collected from 14 swine and poultry operations in the U.S. Midwest and were submitted for gas chromatography-mass spectrometry (GC-MS) analysis. A total of 55 organic odorants were quantitated, including fatty acids, alcohols, aldehydes, ketones, phenols, and nitrogen-containing compounds. Those compounds together accounted for 0.46% ±0.20% of fresh feed mass, with the highest percentage (0.54% ±0.19%) found at layer hen houses and the lowest percentage (0.38% ±0.14%) at swine farrowing houses. Acetic acid and ethanol were most abundant, accounting for 0.22% ±0.13% and 0.13% ±0.07% of fresh feed mass, respectively. Fecal indicators, including indole and skatole, were <5 ppm by mass. Principal component analysis (PCA) revealed that the variability in odorant composition was largely ascribed to two loading factors that were dominated by acetic acid and ethanol, respectively. The odorant composition of feed samples showed no significant effect by animal operation type, while a gradual seasonal change was noted. This study is expected to improve the understanding of the causes of odorants in animal feeds and their implications for animal health and production performance. Keywords: Animal feed, Animal operation, GC-MS, Odorant, Principal component analysis.