Corn Quality Concerns: The two main questions I’ve received: “Are you hearing others mentioning low/variable test weights on corn?” and “Are you hearing of loads being rejected (to ethanol plants) due to mycotoxins?” While I’m unsure how widespread this is, I have been receiving these questions. A reminder to check your grain quality if you haven’t already been hauling or checking it.
Test Weight is a volumetric measurement (weight of corn grain per unit of volume), and as such, doesn’t directly correlate with yield. Standard corn test weight is 56 lbs/bu (1 bushel is 1.24 cubic feet). The size, shape, slipperiness of surface, and density of the kernel impacts test weight. Hybrids can show differences in test weight. Test weight is different than kernel weight, and thus not directly correlated with yield. Test weight gets at how tightly packed the starch is within the kernel. Reducing kernel moisture can allow for increased test weight if the starch loses water allowing for it to be packed more tightly within that kernel. Dry kernels that slide past each other may pack better allowing for increased test weight.
Lower test weights can result with disease, insect, and environmental stresses that impact photosynthesis and the movement of nutrients to the kernel during grain fill. These can include foliar and stalk diseases, drought stress, lack of nutrients, freeze prior to physiological maturity, late planting, and below normal temps during grain fill. Rewetting of kernels in the ear can impact test weight as kernels can swell and not shrink back to the same shape as previously. We know that moisture events happened after physiological maturity causing some sprouting of kernels in some ears prior to harvest. We did have high foliar disease pressure this year and reduced stalk quality. Compromised integrity of the kernel due to insect, disease, and mechanical damage can also impact test weight. I didn’t see the amount of kernel damage as I did in 2018. But there are certain hybrids that are high yielding and widely planted that I tend to see starburst patterns on kernels (due to Fusarium) and shortened husks exposing ear tips to more insect damage/ear molds. There are also hybrids that had a large amount of top dieback, husk tissue that turned brown early, or refuge in a bag plants that died early in fields. All of these may be factors potentially impacting test weight as well. Thinking about photosynthesis, we had reduced solar radiation during grain fill. I can’t help but think that could also impact it but didn’t easily find research that correlates solar radiation to test weight. There’s research correlating solar radiation to yield and kernel weight, though.
Regarding vomitoxin levels, the starburst patterns on kernels, insect damage leading to
ear molds, wet corn not properly dried or cooled in bins can all impact greater Fusarium growth and the potential for vomitoxin to be produced. If vomitoxin (also called DON) is an issue, concentrations can triple in the ethanol process of producing the distiller’s grains. Hogs and poultry are more sensitive than cattle, so the end user may be a factor in addition to the vomitoxin levels. I don’t know the levels being rejected so I can’t speak more to this.
York County Corn Grower Tour: Corn growers and spouses are welcome to join us February 3 for a tour of ag industries in the Lincoln area. We will meet at the York Co. Extension Office at 7 a.m. and will carpool leaving at 7:15. Our first stop will be RealmFive which focuses on wireless connectivity for ag operations. We will then tour Smart Chicken in Waverly which offers retail- and foodservice-packaged organic chickens and antibiotic-free chickens from Kansas, Iowa and Nebraska. Lunch at Lazlos is next followed by learning about the UNL hops program and research using corn gluten meal and soybean meal. Possibly another stop on way home. Please RSVP to me at firstname.lastname@example.org if you’re interested in attending by Feb. 2nd. Hope to have a good group who can join us! Flyer at jenreesources.com.
Last week I was receiving text messages from a few of our farmers about corn harvest results from damaged corn. Low levels of mycotoxins are being detected in samples thus far, thankfully.
Here’s What the Numbers Mean…
For aflatoxin, the U.S. Food and Drug Administration has set a recommended limit of 20ppb (parts per billion) for dairy animals, 100 ppb for breeding animals, and 300 ppb for finishing animals. To put this is simpler terms, a sample would need 20 affected kernels out of a billion kernels to be at the legal limit for dairy animals. So far, most samples are coming up at 5-6ppb which is very low.
For fumonisin, 20ppm (parts per million) is the recommended limit set by FDA for swine, 30ppm for breeding animals, 60ppm for livestock for slaughter, and 100ppm for poultry for slaughter. So, this would mean 20 affected kernels in a million kernels could cause a problem for swine. Again, our levels are averaging closer to 5ppm right now which are low.
Deoxynivalenol (DON) also known as vomitoxin is another mycotoxin being tested from grain samples. This mycotoxin causes reduced weight gain and suppresses animal feeding, especially in swine. Concentrations greater than 10ppm can result in livestock vomiting and totally refusing feed. FDA has recommended that total feed levels of DON not exceed 5 ppm for cattle and chicken, and 1 ppm for swine.
It is very important to sample from several places in the grain to get an accurate sample for damage and mycotoxins. It is also very important that black light tests are not used to determine the presence or absence of mycotoxins. Some of these mold fungi produce a compound that fluoresces under black light, but research has shown that this quality does not consistently predict the presence of mycotoxins (often provides false positives). Finally, before any of your storm-damaged corn is put in a bin, call your insurance agent out to get a sample!
Protecting Your Health with a Mask
There is some great information from the University of Nebraska Med Center on what types of masks to use to protect your health from molds and potential mycotoxins. Some people tend to have more sensitive immune and respiratory systems than others, so I’d highly recommend checking out these short videos.
With the recent sprouting of grain on the ears and with more producers now learning what percent loss their crop insurance is determining for each field, I felt it would be good to talk about feeding this damaged grain again. This post is written by Dr. Dee Griffin, DVM at UNL’s Great Plains Veterinary Education Center at Clay Center. I appreciate Dee’s willingness to provide this information from a Veterinarian’s perspective.
Also a note, to date we have not found Aspergillus in our hail damaged fields. The grain molds we are seeing are Diplodia and Fusarium. Diplodia does not have the potential to produce mycotoxins. Fusarium has the potential of producing fumonisin, vomitoxin, or DON. You can bring forage samples to Husker Harvest Days this coming week to the IANR building and have them tested that day for nitrates for free if you wish.
Dr. Griffin writes: Any time a growing grain producing plant is damaged there is a potential for changes in the plant or grain on the plant contaminated with fungus/molds to grow. The most common change in stressed plants is the accumulation of nitrates. Aspergillus or Fusarium will be the most likely fungi to be contaminating harvested grain from storm damaged corn in our area.
It is really important to know that most molds are not toxic. Therefore just because mold growth is observed doesn’t mean the feedstuff will harm livestock. Even though a mold may not be toxic it can still cause feed refusal. Not all livestock species are equally sensitive to mold contamination and not all production groups are equally sensitive. For instance pregnant and young animals are more sensitive than mature non-pregnant animals.
Nitrate accumulation in stressed plants can cause be harmless or cause serious harm depending on:
- the level of nitrate in the feed harvested from stressed plants,
- on the life stage of the animal,
- and on the species of animal.
Nitrates accumulate in the forage portion of the plant, so nitrates are not a concern in grain harvested from stressed plants. Additionally, it is important to know nitrate levels will always be highest in the bottom part of the plant and lowest in the top foliage. Nitrate testing is simple and reasonable quick. Your local UNL Extension Educator can help you locate the nearest facility that does forage nitrate testing.
Feed containing nitrate levels less than (<) 1000 parts per million (ppm) seldom are associated with an animal health concern. Feed containing nitrate levels greater than (>) 1000 ppm may be a concern in younger animals and levels >2000 ppm should not be fed to pregnant cattle. Feeder cattle are reasonably resistant to nitrates but feeds containing >4000 ppm should not be fed to any animals.
Molds in corn grain of concern could be either Aspergillus or Fusarium. Your UNL Extension Educator can be a great help in identifying mold growing on ears of your storm damaged corn before the grain is harvested. Both of these fungi are potentially dangerous when found in livestock feed. Toxins produced by molds are extremely stable, therefore if a significant level is found, the level will not decrease over time. Silage produced from damaged plants and grain harvested from mold infested plants is potentially a problem.
Good silage management is critical to lessen the likely hood of continued mold growth after ensiling. Proper packing to remove oxygen and improve fermentation which ensures the pH will be below 4.5 is critical.
You can’t look at harvested grains from storm damaged fields and visually identify mycotoxins. Corn grain from storm damaged fields can … and mostly likely should … be tested for mycotoxins before feeding to livestock. Your local UNL Extension Educator, nutritionist or veterinarian can help with mycotoxin testing.
Proper sampling is crucial to getting reliable results back from the laboratory. A “grab sample” is not adequate. The sample submitted to the lab should be representative of the entire load, bin, pit or pile of feedstuff being evaluated.
The steps are simple
- If sampling a field before harvest, sample at least two dozen ears that appear to have mold growth and submit all the ears to the laboratory for mycotoxin evaluation
- If sampling after harvest, take multiple samples uniformly from throughout the silage or grain in question
- The sample should be taken from what would be used in a single load of feed
- That means, if five loads of feed could be made from a 50,000 lb semi-load of corn, collect not less than five samples from the semi-load of corn
- The sample should be based on sample volume not weight
- For instance, collect “coffee can” size samples
- Mix all the all samples together that were collected from the feed in question
- For instance, if 10 coffee can size samples were collected from across the face of a silage pit, pour all 10 samples onto a plastic sheet and thoroughly mix them together
- Next, collect a single sample from within the 10 mixed samples
- Submit the single sample to the laboratory
The laboratory results usually will provide some recommendations for how the feedstuff can be used. There is an old saying, “Dilution is the solution …” meaning in this consideration, that many feedstuffs that contain higher levels of mycotoxin than would be acceptable, might be usable if a sufficient amount of non-mycotoxin contaminated feedstuff is used to dilute the mycotoxin. Your UNL Extension Educator, nutritionist or veterinarian can help evaluate the possible uses of a damaged feedstuff containing unacceptable levels of a mycotoxin.