For livestock and poultry producers, grain quality has been an increasing concern during 2019. The quality concerns with the 2018-2019 corn crop were well known even before the harvest finished. The cold, wet growing conditions during 2018 were ideal for the growth of mold and wild yeast and ultimately the formation of harmful mycotoxins. Mycotoxins are the metabolites of certain mold species. Mold and wild yeast are fungi which can continue to grow in storage and their presence in finished feed can impact livestock and poultry performance.
Coming out of the field, corn started with high levels of mold and mycotoxins. As in prior years, stored grain loses quality over time and mold growth contributes to the loss of energy, amino acids and vitamins. Even when stored correctly, corn loses quality over time. So, what is Kemin finding in the 2019 corn crop?
Kemin Customer Laboratory Services (CLS) analyzes corn from all over the U.S. each year. Valuable information is gained from the samples submitted and is summarized in the report below.
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 received in the second quarter of 2019 (Figure 1). The graph shows the results of samples received from October 5, 2018 until June 28, 2019. Of the 270 corn samples evaluated for mold count since harvest, 17% 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 71% 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 per gram (CFU/g) of mold found on corn samples submitted to Kemin CLS.2
Which mold species is most common in 2019? Of the 270 samples submitted for mold evaluation, Kemin evaluated 119 corn samples (44%) for mold species. Since harvest, the most common mold found was Fusarium spp. More than one mold species was found in 34% of the corn samples submitted, and 89% 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 23% 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., which was found in 13% of the corn samples submitted to Kemin CLS.
Table 1. Summary of mold found on corn samples submitted to Kemin CLS.2
|
Number of Samples |
Percentage of Total / Percentageof Mold Identified |
Corn samples submitted for mold count |
270 |
100% |
Corn samples submitted for mold identification |
119 |
44% / 100% |
Samples with more than one mold identified |
40 |
15% / 34% |
Fusarium (alone or in combination) |
106 |
39% / 89% |
Fusarium alone |
67 |
25% / 56% |
Penicillium mold |
27 |
10% / 23% |
Trichoderma mold |
15 |
6% / 13% |
Aspergillus mold |
11 |
4% / 9% |
Mucor mold |
3 |
1% / 2% |
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 enough 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.
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 152 corn samples for the presence of mycotoxins (Table 2). Notice that 44% 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
|
Number of Samples |
Percentage of Total |
Average Level |
Corn samples submitted for mycotoxin evaluation |
152 |
–– |
N/A |
Corn samples with more than one mycotoxin |
67 |
44% |
N/A |
Aflatoxin |
7 |
5% |
27 ppb |
Zearalenone |
41 |
27% |
143 ppb |
T-2 Toxin |
50 |
33% |
48 ppb |
DON (Vomitoxin) |
47 |
31% |
1.29 ppb |
Fumonisin |
112 |
74% |
2.73 ppm |
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. The nutritional value of moldy grains for broiler chicks. Poultry Science. 61:2247-2254.
4Kao, C., and R. J. Robinson. 1972. Aspergillus flavus Deterioration of Grain: Its Effect on Amino Acids and Vitamins in Whole Wheat. 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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