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The 2016 corn harvest is underway, albeit slowly and riddled with extremely challenging weather conditions across the upper Midwestern U.S. Much of Wisconsin (and the Midwest) have experienced two or more inches of rain, beyond normal rainfall totals per year. “Unfortunately, this excessive rain is falling on top of a corn crop that has reached, and in many cases passed silage maturity, making it difficult to chop and ensile the high-yielding crop that looked to be a “sure-thing” a month ago,” comments John Goeser, Rock River Laboratory’s Animal Nutrition, Research, and Innovation Director.“Plus, fungal pressure has crept in likely due to the extra moisture.” [Figure 1] visually depicts the amount of rainfall seen in these regions, relative to the long-term normal.
Recently, Prof Damon Smith, University of Wisconsin-Madison Plant Pathologist, observed and discussed late-season corn diseases, citing the appearance of Northern corn leaf blight. “Professor Damon has also shared that several consultants in the field are discussing how stalk rot and fungal disease prevalence appears heavier this year,” says Goeser. “These fungal insults could be appearing because of a variety of factors, including this excessive moisture during the growing season.”
With these conditions in place, Goeser offers answers and expectations for producers and their consultants to consider for feed quality, stability, and cleanliness from this 2016 corn crop harvested as corn silage, snaplage, high moisture or dry corn.
The weather is wet but the plant is dry. How should we manage the remainder of corn silage harvest?
“Despite extremely wet conditions, on average plants grew aggressively earlier in the season and appear to be maturing through the rainy month,” explains Goeser. “Typically, Rock River Laboratory observes freshly chopped whole-plant corn moisture decreasing in samples throughout the harvest season. This year, we have observed moisture content trending down at a seemingly faster pace, suggesting either advanced maturity or a disease-pressured crop.” [Figure 2]. Goeser continues that harvesting the crop at the correct dry matter content, or approximately 35% on average, depending on silo type, is critical for effective ensiling and preservation to feed-out this year.
What impact will this have on yield, quality and ensiling?
With the exception of fields that were planted late, or in regions that experienced hail damage, flooding or soggy conditions too wet to harvest, corn silage yield output has largely already been determined. These late-planted or damaged areas will likely experience substantial yield tonnage losses, among other issues.
“Relative to yield, the corn plant's health and cleanliness are of equal or greater concern,” says Goeser. “Epiphytic [meaning natural and wild] mold and yeast measures on standing or fresh plants within the Midwest are typically in the 1,000,000’s,” explains Goeser (Lin et al., 1992; Rock River Laboratory unpublished data). “We’ve recognized increasing mold counts in both fresh and fermented feed and total mixed ration samples the past five years and this trend will undoubtedly continue.”
Aggressive (low pH) ensiling will help suppress these anti-nutritional microbes, but with fungal disease showing up earlier this year and substantial rain through harvest, the Midwest will likely be dealing with mold challenges.
Beyond mold and yeast, Goeser tells the story of soil-born enterobacteria (think Clostridia, Salmonella, E. coli, etc.) that may also be present in larger concentrations with added soil contamination and challenged ensiling. Flooding or mud splashing on the crop or being tracked into the forage by tractors will add to soil contamination and even more bacterial challenges.
In addition to recognizing these harvest challenges and the potential resulting effects on the crop, Goeser recommends aggressive management through simple steps that producers and their harvest team can take to optimize the crop at hand, with the following points:
1. Harvest at the appropriate plant or grain maturity and whole-plant dry matter content to optimize fermentation and preserve nutrients.
2. Avoid tracking mud onto chopped corn where possible.
3. Use a research-backed forage preservative, preferably one with mold and yeast controlling abilities.
Food-grade preservatives (e.g. acids, benzoates, sorbates, etc.) and L. buchneri inoculants have been shown to help control yeast and mold.
Apply these preservatives at recommended and aggressive rates as the bacterial and fungal control is dose-responsive.
4. Cover the bunker or pile between chopping days if rain stops the harvest.
5. Seal the silo to the best of your abilities, including tops, edges, walls and ends.
6. Visually assess the crop and feel for heating within the first few days when opening the silo to feed out. Monitor animal performance closely.
Assess mold and yeast levels after several weeks into the silo and consider evaluating for vomitoxin (Deoxynivalenol or DON) as a mycotoxin and marker for other toxins.
High moisture or dry corn crops
1. Monitor grain maturity and moisture content.
2. Process the corn accordingly with dry matter at harvest:
For corn wetter than 30% dry matter, a coarser grind can be tolerated.
For corn drier than 25% dry matter, slower and less fermentation can be expected. Grinding must be finer and uniform. This corn will also feed more like dry corn than high moisture corn.
3. Consider mold and yeast control strategies similar to those described above.
4. Aggressively ferment or dry this challenged crop adequately in order to stabilize the grain.
This harvest season, the weather is challenging us, and management must be aggressive as the room for error does not exist. Producers and their advisors should closely communicate to best understand the situation at hand for their farms and devise a diligent and focused management strategy to mitigate and lessen the potential nutrition, health and profit-robbing factors associated with this year’s corn crops.
Founded in 1976, Rock River Laboratory is a family-owned laboratory network that provides production assistance to the agricultural industry through the use of advanced diagnostic systems, progressive techniques, and research-supported analyses. Employing a team of top specialists in their respective fields, Rock River Laboratory provides accurate, cost-effective, and timely analytical results to customers worldwide, while featuring unsurpassed customer service.