Throughout much of the U.S. corn growing region, 2017 was best characterized as a mixed bag. Conditions in the spring allowed for early planting and some regions of the country hadideal rain, while large portions of the country experienced near drought conditions. Then, when harvest was ready to begin, the rains began. Delayed harvest was common and slow dry-down resulted in even more delays. Despite all these challenges, corn growers produced more than 14.5 billion bushels of corn. But what was the impact of the late season rain on quality?
Moisture helps wild yeast and mold grow. This is especially problematic in standing corn and grain in storage. Mold itself can impact livestock and poultry performance, but mycotoxins, once formed, are especially difficult to manage. Often, the only solution available is to dilute contaminated grain with clean grain, or use a flow agent with demonstrated efficacy against mycotoxins.
Kemin Customer Laboratory Services (CLS) analyzes corn from all over the United States. Valuable information is gained from the samples submitted and is summarized in the report below.
Corn harvested in 2017 had moderate levels of mold at harvest. The samples received at Kemin CLS contained higher levels of mold over time (Figure 1). The graph shows the results of samples received from October 3, 2017, until December 11, 2017. Of the 77 corn samples evaluated for mold count since harvest, 9% showed mold levels above 1 million colony forming units per fram (CFU/gram). Dairyland Labs recommends producers discount energy by 5% for mold levels over 1 million CFU/g. Note that 30% 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 formin units (CFU) of mold found on corn samples submitted to Kemin CLS.
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 77 samples submitted for mold evaluation, Kemin evaluated 73 corn samples for the species of mold. Since harvest, the most common mold found was Fusarium spp. More than one mold species was found in 44% of the corn samples submitted and 63% 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 45% 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 19% of the corn samples submitted to Kemin CLS.
Table 1. Summary of mold found on corn samples submitted to Kemin CLS.
|Number of Samples||Percentage of Total / of ID|
|Corn samples submitted for mold count||77||100%|
|Corn samples submitted for mold identification||73||95% / 100%|
|Samples with more than one mold identified||32||42% / 44%|
|Fusarium mold (alone or in combination)||46||60% / 63%|
|Fusarium alone||26||34% / 36%|
|Penicillium mold||33||43% / 45%|
|Trichoderma mold||14||18% / 19%|
|Unknown||6||8% / 8%|
|Mucor mold||5||6% / 7%|
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%. Research by Kao and Robinson in 1972 showed that mold growth had a dramatic effect on the nutritional content of grain and feed. Finally, for dairy cattle, Penn State University suggests that digestibility of moldy feed may be decreased sufficiently to reduce energy content by 5%.4 Such feeds are also less palatable and may lower the intake of energy, dry matter and critical nutrients.
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 note, once a mycotoxin is formed, they do not degrade.
Since the conclusion of the 2017 harvest, Kemin CLS has evaluated 77 corn samples for the presence of mycotoxins (Table 2). Notice that 61% 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.
|Number of Samples||Percentage of Total||Average Level|
|Corn Samples submitted for mycotoxin evaluation||77||100%||N/A|
|Samples with more than one mycotoxin||47||61%||N/A|
|T-2 Toxin||51||66%||51 ppb|
|DON (Vomitoxin)||42||54%||1.46 ppm|
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:
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.