Skip to main content

Strategic Farming: Let's talk crops! January 19 session covers management considerations for grain and silage corn

By Angie Peltier, Extension crops educator, and Phyllis Bongard, Extension educational content development and communications specialist

Corn silage. Photo: University of Wisconsin-
Madison Extension
It should be a surprise to none that drought dominated conversation topics during the 2021 growing season. As dairy or beef cattle producers struggled to source enough feed to support their herds, using  corn crops initially planned for grain harvest for livestock feed instead was not an uncommon phenomenon. While there are similarities in how best to produce corn for grain or silage, there are also important differences that may influence crop management during the 2022 growing season. On January 19, 2022, Drs. Joe Lauer, University of Wisconsin (UW)-Madison corn agronomist, and Luiz Ferraretto, UW-Madison ruminant nutritionist, joined UMN Extension educators for a wide-ranging discussion of how best to manage corn harvested as grain or silage crops.

Watch a recording of this webinar below.

Factors that affect silage quality

Whether corn is to be grown for grain or silage, one of the top factors that can influence yield and quality is hybrid selection. Dr. Lauer told the Strategic Farming audience that top- and bottom-performing hybrids can vary by up to 70 bu/A when grown for grain and up to 3.5 tons of dry matter/A when grown for silage. A good forage crop tends to have high yield, be of high energy content (low in fiber and high in protein contents), have the proper moisture for harvest and ensiling for longer-term storage and a high potential for intake by ruminants. Silage corn has most of these features except tends to have lower protein content than other forages. When selecting a silage hybrid, focus on those that provide the highest tonnage (yield), milk per ton (quality) and milk per acre (quality).

From a milk protein perspective, silage quality varies considerably over the life of the corn crop and tends to be highest at corn pollination and higher still when kernels are halfway between milk and kernel maturity. Corn kernels also tend to be the driest portion of the crop when chopped for silage and so moisture going into storage can be easily adjusted by adjusting chopping height. “We know that we can lose about 15% of yield by adjusting the cutter bar a foot higher, but in doing so we leave the lowest quality plant parts in the field and so can actually significantly improve silage quality,” according to Dr. Lauer.

Nutrient content of silage corn

When corn is chopped for silage, approximately 50-55% of the dry matter is green plant material (stover) such as leaves and stalks and around 45-50% is grain. Approximately 40 to 70% of the stover is digested by ruminants, and digestibility is dependent upon hybrid, cutting height and moisture, efficacy of fermentation and crop maturity. Approximately 30% of the grain is starch, of which 80-98% is digestible in the rumen, and dependent upon the size of the kernel particles.

Maturity of the crop at chopping time can also affect how hard kernels are, with the harder the kernels, the less digestible they are. Dr. Ferraretto says that when too-dry or too-mature corn is chopped for silage, less breakage of kernels occurs; and as both dairy and beef cattle need to eat 60 to 70 lb of feed (dry matter) per day, they tend to eat far faster and break far fewer kernels than we would imagine, meaning that much of the crop’s starch content moves through the rumen undigested.

Maturity at harvest can affect fermentation quality, with the more dry matter and the less moisture content, the worse the condition for fermentation. This is because the microorganisms that carry out fermentation cannot move and spread as well in the silo, bunker or bag containing the silage crop. Dr. Ferraretto suggests that when using whole plants chopped to make silage, “we usually suggest people shoot for 65-67% moisture content as this is the optimum moisture content for fermentation”. Silage pH and storage length is also affected by moisture content, with less stable, higher pHs occurring with higher dry matter content. Good fermentation also affects the digestibility of starch, the most energy-rich contents of silage.

Other factors to consider

A high yielding variety - from a grain perspective - should also be a consideration as this can offer the grain- and silage-corn producer some flexibility as to whether or not to chop the crop for silage or harvest it for grain. Good standability and pest resistance are also important considerations for flexibility in crop use as healthier foliage tends to result in greener, higher-quality silage. Over the years in the Wisconsin corn hybrid trials, transgenic hybrids (particularly those that express European corn borer Bt traits) have tended to out-yield conventional hybrids and so Dr. Lauer urges great care when selecting high-yielding conventional hybrids.

Fielding audience questions

Drs. Lauer and Ferraretto answered many audience questions that were either asked live during the webinar or posed when attendees registered for the series, including: What about feeding Enogen(R) corn? How do fungal pathogens affect fermentation? How does one price silage corn? What about rotating Bt traits? Should we consider foliar fungicides for silage corn that has the brown midrib trait to improve standability?

Join the webinar series

University of Minnesota’s Strategic Farming: Let’s talk crops! webinar series, offered Wednesdays through March, features discussions with specialists to provide up-to-date, research-based information to help farmers and ag professionals optimize crop management strategies for 2022.

With increasing herbicide resistance and a decrease in effective management tools, weed management will continue become more complicated. Join Drs. Tom Peters and Debalin Sarangi on February 3 as we discuss strategies for effective weed management in the years to come. For more information and to register, visit

Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!

Print Friendly and PDF