Mold and Mycotoxin Report: 2018/19 Corn Crop

The corn growing season in 2018 was very similar to 2017 across much of the U.S. – nearly ideal. There were pockets in the southern corn belt which experienced drought and the northeast states had too much rain, but overall the growing season was excellent for another bin-busting crop. Then, in September, just as the harvest started, the rain started. In the Northeast, where the growing season was saturated with rain, the fall was a continuation of excessive rain. In the Upper Midwest, harvest delays pushed the completion of harvest well into December as growers waited for fields to dry.

Wild yeast and mold growth is a concern in corn, especially during years of excessive rain. Mold continues to grow on standing corn, and mold can continue to grow even after corn is stored if it is not stored correctly. Research has demonstrated the presence of mold can impact livestock and poultry performance and mycotoxins – which are produced by mold – are especially difficult to manage. Often, the only solution available to handle mycotoxin contamination is to dilute contaminated grain with clean grain or sequestering agents with demonstrated efficacy against mycotoxins.

Corn in human hands

Kemin Customer Laboratory Services (CLS) analyzes corn from all over the U.S. Valuable information is gained from the samples submitted and is summarized in the report below.

Mold Levels

Corn harvested in 2018 had high levels of mold at harvest. The samples received at Kemin CLS contained high levels of mold right after harvest, and those high levels are still found in samples in early 2019 (Figure 1). The graph shows the results of samples received from October 5, 2018 until January 7, 2019. Of the 94 corn samples evaluated for mold count since harvest, 11% showed mold levels above 1 million colony forming units per gram (CFU/gram). Dairyland Labs, Inc. recommends producers discount energy by 5% for mold levels over 1 million CFU/g.1 Note a whopping 65% of corn samples have between 100,000-1,000,000 CFU/g. Even these mold levels can impact animal performance, and mold counts can increase as quality suffers during storage.

Figure 1. Colony forming units (CFU) per gram of mold found on corn samples submitted to Kemin CLS.2

Not all samples submitted to Kemin CLS for mold evaluation are subjected to an evaluation of the species of mold — it is the preference of some customers to only seek a mold count, not a full species evaluation. Of the 94 samples submitted for mold evaluation, Kemin evaluated 89 corn samples for the species of mold. Since harvest, the most common mold found was Fusarium spp. More than one mold species were found in 32% of the corn samples submitted and 88% of the corn samples submitted had Fusarium mold. Fusarium mold is classified as a "field mold" because it requires available water to multiply. It will often appear white to pink in color. However, just because it is a field mold does not mean it will not grow in storage. The second most common mold species, found in 20% of the corn samples submitted, was Penicillium spp. This is a storage mold and will often appear gray or greenish in color. Lastly, the third most common mold was Trichoderma spp. and was found in 11% of the corn samples submitted to Kemin CLS.

Table 1. Summary of mold found on corn samples submitted to Kemin CLS.

The presence of mold in feed is not often considered an issue in livestock and poultry production, but research demonstrates the detrimental impact mold can have on performance. Research by Bartov, published in The Journal of Poultry Science in 1982, showed mold development reduced fat content from 3.9% to 2.2%.3 Research by Kao and Robinson in 1972 showed that mold growth had a dramatic effect on the nutritional content of grain and feed.4 Finally, for dairy cattle, Penn State University suggests that digestibility of moldy feed may be decreased sufficiently to reduce energy content by 5%.5 Such feeds are also less palatable and may lower the intake of energy, dry matter and critical nutrients.

Mycotoxin Levels

Kemin CLS also evaluates corn samples for mycotoxin levels. Mycotoxins are formed by mold under certain conditions. While molds form mycotoxins, it is important to note that the presence of mold does not mean mycotoxins are present. By the same token, mycotoxins are often found when mold is no longer detected. Also of note, once a mycotoxin is formed, it does not degrade.

Since the conclusion of the 2018 harvest, Kemin CLS has evaluated 94 corn samples for the presence of mycotoxins (Table 2). Notice that 28% of the corn samples have more than one mycotoxin. This is particularly important to note as multiple toxins can have a pronounced impact on livestock performance.

Table 2. Summary of mycotoxins found on corn samples submitted to Kemin CLS.2

Kemin Recommendations

First, contact your Kemin representative for more information on implementing a comprehensive mold and mycotoxin control program. Your Kemin representative has information and expertise which will increase the effectiveness of your program.

Second, complete the following:

Test corn for mold and mycotoxins – storage conditions greatly impact grain quality.

With mold levels near threshold levels, which can impact performance of the 2018/19 corn supply, use Myco CURB® Dry at 2 lbs/ton or Myco CURB® Liquid at 2 lbs/ton to control mold growth in stored grain or complete feed.

Use KALLSIL at 2-4 ounces/head/day in cattle or 2-4 pounds per ton of swine or poultry feed. KALLSIL is a dry anti-caking aid which helps reduce caking and improves flowability of feed ingredients. Published research has demonstrated that many anti-caking products can reduce several of the negative impacts associated with mold and mycotoxin contamination in feed.

 

References

1https://www.dairylandlabs.net/molds-and-mycotoxins/mold-interpretation. Accessed November 23, 2018.

2Data from Kemin CLS corn samples submitted as part of an annual monitoring program.

3Bartov, I., N. Paster, and N. Lisher. 1982. Poultry Science. 61:2247-2254.

4Kao, C., and R. J. Robinson. 1972. J. Food Sci. 37:261.

5Adams, R. S. K. B. Kephart and V. A. Ishler. Mold and Mycotoxin Problems in Livestock Feeding. Department of Dairy and Animal Science, Lawrence J. Hutchinson, Department of Veterinary Science, and Gregory W. Roth, Department of Agronomy. Access from https://extension.psu.edu/mold-and-mycotoxin-problems-in-livestock-feeding on December 23, 2018.

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