Survey of Mycotoxins in 2016 US Corn

Mycotoxins, toxic secondary metabolites produced by common molds infecting grains and forages, can contaminate feed ingredients. The negative effects on livestock are dependent on the level, type, and duration of exposure as well as the age, species, and general health status of the animal. The current study’s objective was to determine the occurrence and potential risk of mycotoxins to livestock species in the 2016 US corn crop in comparison with the previous year. In total, 318 corn samples from 25 states (2015 harvest) and 387 corn samples from 26 states (2016 harvest) were submitted for analysis as part of the annual Biomin PROcheck^® Mycotoxin Survey. Samples were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) for the presence of mycotoxins from six 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). A summary of the results is provided in Table 1. Individual toxin levels and co-occurrence from each year were compared using non-parametric tests (GraphPad Prism).

In the 2016 sample pool, 90% of the corn samples had least one mycotoxin detected. Compared to 2015 corn, 2016 corn had higher contamination levels of DON and FUM (p < 0.001). Additionally, co-occurrence of more than one mycotoxin increased from 2015 to 2016 (46% vs. 67%, p < 0.001). Toxins produced by Fusarium fungal species (DON, FUM and ZEN) were frequently detected in combination; 21% of samples tested positive for all three toxins. Co-occurrence of mycotoxins can result in more severe detrimental impacts on animal health and performance.

The high prevalence as well as large number of samples above the FDA recommended level (42% of positive samples over 1000 ppb) positions DON as the greatest mycotoxin threat to livestock from the 2016 US corn harvest. However, the high prevalence of co-occurrence suggests FUM and ZEN also present significant risks to animal health in 2016 corn.

 

Table 1. Summary of mycotoxin analysis.

Year	2015						2016
Parameters	DON	FUM	ZEN	Afla	T-2	OTA	DON	FUM	ZEN	Afla	T-2	OTA
Positive samples (%)	72	52	17	1	0.3	2	75	72	42	6	2	0
Median [ppb]	400	500	107	23	200	3	785	1700	163	7	277	NA
90th percentile  [ppb]	1500	2960	600	87	NA	59	4580	9340	616	53	400	NA
Maximum contamination [ppb]	5670	16300	1200	108	200	100	11700	119400	19000	139	401	NA