Mycotoxins are toxic secondary metabolites produced by a variety of molds which may infect most crops. Severity of the negative effects associated with these toxins is dependent on the level, type, and duration of exposure and age, species, and health status of animals. Distillers dried grains with solubles (DDGS), a by-product of the ethanol industry, are a common feed ingredient for various livestock species. During ethanol production, mycotoxins become more concentrated in DDGS than in the original corn. The objectives of the current study were to determine the occurrence of mycotoxins in US corn DDGS samples and to evaluate the potential risk posed to livestock. Seventy-nine corn DDGS samples from 14 states were analyzed between 2015 and 2016 as part of the Biomin PROcheck mycotoxin survey. Samples were analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS) technique for the presence of 17 mycotoxins from the following 6 major mycotoxin groups: Type B trichothecenes including deoxynivalenol (DON), fumonisins (FUM), zearalenone (ZEN), aflatoxins (Afla), Type A trichothecenes including T-2 toxin (T-2), and ochratoxin A (OTA). Each DDGS sample in the current survey was contaminated with at least one mycotoxin while 96% of samples contained more than one mycotoxin. The presence of more than one mycotoxin may result in an intensification of the negative effects of each mycotoxin present. The percent of positive samples, mean of positives [ppb], standard error of the mean (SEM) of positives [ppb], and maximum of positives [ppb], as well as risk threshold [ppb] for the 6 major mycotoxin groups are presented in Table 1. Deoxynivalenol was detected in 100% of samples and FUM and ZEN were also highly prevalent. Due to the high prevalence (100%) and large number of samples contaminated beyond the FDA recommended level (84%), DON poses the greatest threat from US corn DDGS. Table 1. Summary of mycotoxin analysis

Parameter	DON	FUM	ZEN	Afla	T-2	OTA
Positive samples (%)	100	88	71	7	0	1
Mean of positives (ppb)	2,681	3,393	230	12	0	19
SEM1 of positives (ppb)	207	428	24	6	NA	NA
Maximum contamination (ppb)	9,800	18,500	666	37	0	19
Risk threshold (ppb)	900	2,000	200	20	100	100

¹Standard error of mean.