The challenges ranged from delayed planting, excess rain or drought during growth, fungal disease challenges and, in some areas, exposure to multiple frosts. Late harvesting was also very common this year, which in some areas meant chopping frozen whole-plant corn silage. It’s fair to say there is a wide variety of ensiled 2019 corn silage available to feed cows. In order to maintain herd health and high performance, an understanding of what this corn silage is, how it will feed and what is needed to complement or supplement the diet will be needed.
Understanding the 2019 corn silage
Even with delayed harvest, some areas are already feeding 2019 corn silage. It’s important to take representative samples for a comprehensive near-infrared (NIR) analysis on a regular basis. A wet chemistry analysis should be considered and compared to NIR analysis because of the atypical year we have encountered. For the challenged 2019 crop, it will be important to have a more intensive and frequent sampling regime than in a “normal” year.
The first indication of how close to maturity the crop was at harvest and ensiling will be dry matter content. Anything less than 33% dry matter indicates a less mature crop and may show signs of silage effluent seepage in the bunk or pile (image above). Excess effluent seepage is not only a pollution risk if not managed correctly, it also represents a loss of the most digestible nutrients.
Expect the starch content of the crop to be in line with the crop’s maturity. High-moisture, immature crops will likely have much lower starch content, less than 30% on a dry matter basis. Extreme cases may be less than 20% on a dry matter basis. Be aware that this immature corn is likely to be much more rumen fermentable than previous years.
With this in mind, it’s important for 2019 corn silage samples to analyze total starch content, its predicted seven-hour rumen digestibility, along with an associated digestibility rate per hour. As a corollary to the low starch content, expect higher residual sugar content in these samples. Be aware, there may be an increased risk of aerobic instability or wild spoilage yeast activity with these immature corn silages with elevated sugar levels.
Close attention should also be given to the neutral detergent fiber (NDF) content of the crop, listed in the analytical report as “aNDF” content. Expect higher aNDF values on a dry matter basis in low-starch crops. Knowing the aNDF digestibility and the associated rate of aNDF digestion, along with the indigestible NDF fraction or ballast shown as “uNDF240” content, will be important to make these 2019 corn silages work in the rations.
Early feedback from dairy consultants in the field indicate that the local weather effects in some states have yielded 2019 corn silage that have higher-than-expected NDF digestibility with potential higher inclusion rates in ration formulation and a higher rate of passage.
Finally, within the analytical report, it’s worth looking at the total ash content and fermentation profile. The ash content of corn silage is typically 3% to 5% on a dry matter basis. Anything higher than this represents dust or soil contamination, with the risk of unwanted inoculation by bad microbes within the dust/soil contaminant. The extent and type of fermentation achieved will depend on whether or not an effective inoculant was used and the efficacy of the whole ensilage process. A successful corn silage fermentation analysis profile is shown in Table 1.
There may be occasions when the “smell” of the 2019 corn silage, and off-target performance by the dairy herd, may merit a more detailed wet chemistry fermentation profile analysis. Mold and yeast counts may also be useful, along with knowledge of the mycotoxin type and load in the corn silage.
How will the 2019 corn silage feed?
Ultimately, no matter what we assume and what past challenges have shown us, your cows will be the best judge of the 2019 corn silage feed potential. However, some general expectations would be common:
- With the combined challenge on this season’s haylage crop yields (and quality), plus the likely lower yield of 2019 corn silage, some farms will have a problem with lower total forage inventories. This will mean a discussion on alternate ensiled forage sources or the use of non-forage fiber sources as appropriate.
- If the farm was able to store immature and mature corn silage supplies separately, it will be possible to target the different 2019 corn silage qualities to the different productive groups of cows and replacements.
- Be aware, the immature 2019 corn silage starch content will be lower but more readily rumen fermentable. This will likely require the use of more cornmeal in the rations for the more productive cows to maintain energy and total starch content in the rations.
- The immature 2019 corn silage aNDF fractions will likely be higher and could be more digestible than usual. Corn silage is usually the major forage component of dairy cow rations, so be aware of potential higher rates of passage and cognizant of pen appetite limits and dry matter intakes (DMIs), which means keep a close watch on TMR refusals. The tactical use of physically effective fiber at low inclusion levels in some of the rations may be warranted.
- These lower-dry-matter corn silages will need to be continually cross-checked for dry matter weekly at a minimum to ensure correct fresh weight addition to the TMR mixer for the correct forage dry matter inclusion.
Based on all the above, one can expect significant variation in this year’s rations. One can anticipate rumen challenges in the herd, including sub-acute ruminal acidosis. Additional support can be found by using rumen-specific active dry yeast to optimize rumen function.
Some herds will inevitably succumb to some lower gut dysfunction due to downstream effects from compromised rumen fermentation. Strong consideration should be given to feed additives that support low gut health. Dairy farm teams and their consultants are encouraged to do all they can to get cows through this feeding season, including regular and frequent forage analysis, ration formulation tweaks, frequent dry matter checks, proper forage face and drop pile management, regular TMR feeding and push-ups, and ensuring that cows never run out of feed. 
PHOTO: Requirements to get cows through this feeding season include regular forage analysis, ration formulation tweaks, frequent dry matter checks, proper forage face and drop pile management as well as regular TMR feeding and push-ups. Photo by Peggy Coffeen.
Andy Skidmore received his DVM from Kansas State University and his Ph.D. in animal sciences from Cornell University and is employed by Lallemand Animal Nutrition, North America as a technical services – ruminant team member, since 2016.
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Tony Hall
- Dairy Technical Service Manager
- Lallemand Animal Nutrition
- Email Tony Hall
