Getting high with corn silage
August 18, 2020
It’s always interesting to note the variation between regions and farms in regards to how much plant stalk remains in a field following a corn silage harvest. In California, I’ve seen fields cut so close to the ground that worms wouldn’t dare stick their heads above the surface, if, indeed, worms have heads. On the flip side, some Midwest farmers have chosen to leave a field of 2-foot stumps.
How high or low the chopper head is set has a significant impact on both yield and quality. By leaving more of the lower stalk in the field, both the overall fiber digestibility and starch content of the feed will improve significantly. It’s an easy way to essentially turn a conventional grain or silage hybrid into a brown midrib-like feed, with the added benefit of a higher starch content.
There is, of course, some downside to making high-chop corn silage. It comes with some yield reduction. For example, in one comparison of research studies made by John Goeser, the director of nutrition and research at Rock River Labs in Watertown, Wis., corn silage dry matter yield dropped an average of 8% when cutting height was raised from 6 to 18 inches.
In another summary of 11 research trials done by Greg Roth of Penn State University, corn silage yield dropped 7.4% when cutting height was raised from an average of 7 inches to 19 inches. In both research summaries, the yield reduction equated to about 0.5 ton of dry matter per acre, which converts to 1.4 tons per acre on a wet basis.
If high-chop corn silage is being considered, more acres of silage will need to be planted to realize the same tonnage as a low-cut silage.
Additionally, feed ration adjustments likely will need to be made to account for the lower neutral detergent fiber content and the elevated starch content of the higher cut silage. This may mean pulling some corn grain out of the ration and feeding a higher forage ration to maintain milkfat concentration. The research leaves little doubt that more milk can be obtained when cows are fed high-chop corn silage, especially if other forage sources are relatively low in fiber digestibility.
There are a couple of other advantages to high-chop corn silage that don’t relate specifically to improved fiber digestibility and starch content.
Leaving more of the lower stalk in the field will reduce the dry matter content of the harvested crop. This offers the opportunity to begin harvesting earlier and still achieve an optimal harvest moisture. Conversely, if the crop is already too dry, high cutting is not something that should be considered; it will only make a bad situation even worse.
In addition to moisture, the lower stalk also contains the highest concentration of plant nitrates. High cutting corn silage can help reduce nitrate levels if this is a concern.
Give it some thought
High-chopped corn silage is not for every farm and requires some consideration before implementing. It might take a year or two of experimentation to find the cutting height “sweet spot” for an individual farm.
As with brown midrib hybrids, the greatest benefit from high-chopped corn silage will come with feeding it to high-producing cows. This may mean it will need to be stored separately. Before taking the leap to high-chopped corn silage, a serious discussion with your nutritionist is advised.