Corn silage has the advantage over alfalfa when it comes to average yield per acre. Considering the former feedstuff only warrants one harvest a year, it may have a leg up on alfalfa in terms of management, too. But the benefits of including alfalfa in crop rotations and dairy rations can far outweigh the yield gains and cost savings realized by omitting it. Two speakers advocated for these benefits in the field, the feedbunk, and on a balance sheet at the Midwest Forage Association (MFA) Symposium last month in Wisconsin Dells, Wis.

Being someone who learned to formulate rations with corn silage as the only forage source, Luiz Ferraretto can attest to the nutritional attributes that alfalfa brings to the table. The ruminant nutrition specialist with the University of Wisconsin-Madison shared his perspective on pairing alfalfa with corn silage in dairy rations.

Two of the key factors of alfalfa and corn silage’s companionship are their respective crude protein and starch concentrations. Ferraretto explained that both nutrients are needed for microbial protein synthesis in the rumen. Therefore, pairing crude protein from alfalfa with starch from corn silage can translate to better milk production.

Alfalfa and corn silage also complement each other in terms of fiber digestibility. Although alfalfa can have similar levels of neutral detergent fiber (NDF) as corn silage, its higher lignin content contributes to more undigestible NDF (uNDF) compared to corn silage. On the other hand, corn silage fiber is more digestible than that of alfalfa. Ferraretto said both slowly degradable carbohydrates and rapidly degradable carbohydrates are necessary for rumen synchronization.

“At the end of the day, our goal is to make sure we have very good neutral detergent fiber digestibility,” Ferraretto said. “This is what drives performance for dairy cows.”

Expounding on fiber dynamics, Ferraretto highlighted the flexibility of alfalfa particle size in the ration, explaining how it can be used as a tool to complement that of corn silage. Since cows are more apt to sort corn silage particles than haylage particles, he said shortening corn silage particles to improve animal intake while extending alfalfa chop length can help maintain the optimal level of effective fiber for cows.

“Whenever there is a proportion of [corn silage] particles that are too long, cows spend more time at the feedbunk,” Ferraretto said. “Every extra moment that a cow spends at the feedbunk, she’s not resting, and more importantly, she’s not ruminating.”

Production costs

John Goeser is the director of nutrition research at Rock River Labs Inc., a consultant with Cows Agree Consulting, and an adjunct assistant professor at the University of Wisconsin-Madison. Like Ferraretto, he also discussed the complementary aspects of alfalfa and corn silage from a feeding standpoint and from an agronomic lens, claiming that alfalfa is the yin to corn silage’s yang.

Goeser stated that adding alfalfa to a crop rotation can help break up pest and disease cycles that could otherwise occur in continuous corn systems. From a soil health perspective, he added that alfalfa’s deep taproot system can both reduce soil erosion and prevent compaction from harvest equipment.

Morphologically, alfalfa and corn silage couldn’t be more different, Goeser said. One is a perennial cool-season legume and the other is a warm-season annual grass. While these attributes lend themselves to a match made in dairy ration heaven, they warrant quite different inputs and field management. Therefore, to truly reap the nutritional and agronomic benefits of an alfalfa-corn system, Goeser stressed that farmers must know their costs of production per acre.

He projected average feed costs attributable to alfalfa and corn silage for a 500-head dairy to be around $430,000 per year, considering cows receive a high-forage diet comprised of alfalfa haylage and corn silage at a rate of about 30 pounds of dry matter per head per day. However, he purported not enough producers actually know how these expenses add up.

“What really matters is what is in your checkbook at the end of the day,” Goeser asserted. “Milk per ton and milk per acre are index values that help us get an idea of what kind of production potential we can get from an acre of feed, but there isn’t an economic impact.”

Using the Estimated Costs of Crop Production worksheet from Iowa State University Extension, he estimated that growing an acre of alfalfa would cost between $600 to $800, whereas the cost of production for an acre of corn can drive north of $1,000. Part of the difference can be attributed to average dry matter yield of each species, for which he predicted to be roughly 4 tons per acre for alfalfa and 7 tons per acre for corn silage.

The other consideration is the feed’s value per ton relative to other purchased feeds such as soy hulls or soybean meal. In his example, Goeser used FeedVal v7.0 and estimated this to be around $140 per ton of alfalfa haylage (45% dry matter) and $73 per ton of corn silage (30% dry matter). Overall, he emphasized that the cost of production for an acre of corn is roughly $250 more than that of alfalfa.

Margin per acre

Goeser then calculated the margin per acre for alfalfa and corn silage, or the profit a farmer can expect to earn after accounting for the costs of production and crop revenue.

He pegged the margin per acre for alfalfa to be roughly $580, whereas that for corn was about $390. To Ferraretto’s point, Goeser attributed the value of alfalfa protein and its perennial life cycle to its better margins.

The dairy consultant said he has generally steered ration formulation toward higher corn silage inclusion rates for his clients but has grown more apt to leverage alfalfa after evaluating its potential to impact feed costs.

“Not only do alfalfa and corn play well together in terms of management from an agronomic standpoint and nutritionally in the diet, but alfalfa can hold its own from an economic standpoint in terms of margin per acre,” he concluded.