Dealing with low-moisture corn silage

For most, the 2023 corn silage harvest is in the rearview mirror. Corn silage harvest came early for some as the summer heat provided plenty of growing degree days, and many areas experienced a perfect storm for drying conditions. Kernal maturity progressed as plants were running out of water with the lack of rainfall. The breaking point was the extreme heat, wind and relatively low humidity in the days surrounding Labor Day. In one case where we were monitoring whole-plant moisture, we dropped 10 points, from 68% to 58% moisture, in about a five-day period. This greatly exceeds our normal expectations for whole-plant dry down of approximately one-half percentage unit per day.

If you were fortunate to hit ideal corn silage moistures, my comments may be less relevant. For those who ended up waiting on a custom operator or had extended harvest windows through these extreme drying conditions, here are a few tips to deal with low-moisture corn silage.

Harvest, storage challenges

Dry corn silage is more difficult to pack. To compensate, theoretical length of cut is generally reduced. In some cases, additional pack tractors or more weight on the pile is necessary as well. Shortening the theoretical length of cut also allows the kernel processor to work more easily. The importance of kernel processing increases exponentially with drier silage as this kernel is harder to ferment and is less digestible if particle size is not reduced.

Fermentation is generally compromised with low-moisture corn silage for two primary reasons. The first relates back to packing and the initial aerobic stage of fermentation where oxygen is depleted. The longer this initial fermentation stage takes, the greater chance oxygen-loving organisms like yeasts and molds will thrive. The second challenge occurs during the anaerobic phase of fermentation where we can get less-desirable conditions for lactic acid-producing bacteria to flourish. Moisture is critical during this stage. It is generally recommended to add a reputable lactic acid-producing inoculant regardless of moisture; however, it is more critical with dry corn silage because fewer of these active, naturally occurring bacteria are present. Allowing dry corn silage to ferment for longer periods of time is also recommended if inventory allows.

Feeding challenges

How will dry corn silage feed? The answer depends on how you did on the harvest discussion points above. Fermentation is key to breaking down prolamin (the protein matrix in the kernel that surrounds the starch molecules), making the starch more available for microbial digestion. Well-processed kernels also increase the surface area for rumen bacteria to access starch. Poor fermentation or poorly processed kernels will result in more corn in the manure and less available energy to the cow. This can be monitored by testing manure for fecal starch.  

To compensate for lower energy, we may need to feed more corn or other fermentable carbohydrates. Feeding strategies might also include digestible fiber sources such as soy hulls, beet pulp or corn gluten feed. With either approach, we need to feed less forage to make room for these additions. There is a balance between increasing energy and maintaining effective fiber levels in the rumen. Also, beware that reducing silage feed out during warmer weather next summer could be a challenge in terms of spoilage and heating associated with yeast and mold if too little is removed from the face.

If your corn silage was harvested at a lower-than-ideal moisture, realize this is not unprecedented, and many folks have overcome these challenges with minimal interruption. Work with your nutritionist to adjust accordingly, and let the cows tell you the best direction to pursue opportunities.

Barry Visser is a nutritionist for Vita Plus.