Selecting corn hybrids for silage production

Silage hybrid performance

Consistent performance over multiple trials with different soil and weather conditions is critical because next year’s growing conditions cannot be predicted.

A hybrid that performs well in multiple environments will have a high potential of performing well the following year. That’s why dairy producers should select hybrids that perform well over multiple sites in a region.

In the past, the performance of a given set of hybrids could be evaluated over multiple years at a given location, but now that’s less realistic because the lifespan for a typical corn hybrid is just a few years.

To reduce risk, producers should select multiple hybrids based on information from several sources including universities, seed companies and commodity groups. Results from unbiased and replicated trials that include multiple hybrids from different companies are particularly important.

Corn silage trial results

Growers should also use data from individual on-farm corn trials if available, such as those from the following sources:

• University of Minnesota

• Minnesota Corn Growers Association

• Iowa State University

• University of Wisconsin

• North Dakota State University

• South Dakota State University

The importance of yield and quality

Selecting hybrids that produce high corn silage yields is important.

For example, assume a farmer has a 4,000-ton corn silage feed requirement. If Hybrid A yields 33 tons per acre and Hybrid B yields 28 tons per acre, this farmer would need to harvest 143 acres for silage if planting Hybrid B, but only 121 acres if planting Hybrid A.

In this example, selecting Hybrid A over Hybrid B would allowed this farmer an extra 22 acres for grain harvest. At 190 bushels per acre, this would be 4,180 bushels of extra corn to feed or sell, with a value of $16,720 at $4 per bushel.

Silage quality

While this example demonstrates the importance of yield, it does not account for silage quality. Since corn silage is an energy source for animal performance, producers should evaluate both silage yield and quality when selecting hybrids.

Silage yield is commonly presented on both a DM and wet (65 percent moisture) basis. Dry matter yield allows fair comparisons among hybrids harvested at different whole-plant moisture levels.

The many variables representing silage quality can make hybrid selection overwhelming. Consulting with a livestock nutritionist during the hybrid selection process helps ensure that selected hybrids have the necessary nutritive value for your herd.

Milk per ton and milk per acre: An overview

Overall silage quality is commonly summarized in a single variable known as milk per ton, which is calculated using the Milk 2006 corn silage evaluation system. It’s estimated using forage analyses for crude protein (CP), neutral detergent fiber (NDF), NDF digestibility (NDFD), starch and nonfiber carbohydrate.

Milk per ton -- the quality of the silage -- is typically shown along with milk per acre, which is calculated by multiplying milk per ton by silage DM yield. Thus, milk per acre is largely influenced by silage yield, making it possible for a hybrid to have high milk per acre with low milk per ton.

However, because milk per acre combines both yield and quality, and because silage quality is so important, many people look at milk per acre as an indication of silage yield rather than silage yield itself.

How to find a high-quality silage hybrid

When selecting hybrids based on milk per ton and milk per acre, consider the following:

• Aim for hybrids with high values for both milk per ton and milk per acre. These hybrids produce high-quality forage and high silage yield, and are most profitable.

• Hybrids with a low value for milk per ton and a high value for milk per acre have below-average quality but high yield. Silage from these hybrids may be better suited for livestock with lower nutritive requirements than lactating dairy cows.

• Hybrids with a high value for milk per ton and a low value for milk per acre have high quality and below-average yield. These hybrids will have low profitability for dairy producers that grow their own silage, because gains in quality will not likely offset reductions in yield.

• Avoid hybrids with low values for both milk per ton and milk per acre. They have relatively lower yield and lower quality.

Once you’ve identified a hybrid group with high values for milk per acre and milk per ton, base further selection within this group on specific agronomic and forage quality traits.

In general, higher NDF values indicate lower intake and animal performance, while higher values for CP, starch, NDF digestibility and in vitro digestibility imply greater performance potential.

While small changes in forage quality can greatly impact milk production, a less-than-5-percent difference in individual quality traits between hybrids is probably not statistically significant or worth worrying about, especially since milk per ton summarizes overall forage quality.

Transgenic and agronomic traits

When selecting hybrids, it’s important to remember that transgenic insect resistance traits do not increase yield potential. Instead, they protect yield potential when pressured by the target pest. Paying extra for transgenic insect resistance when it’s not needed reduces economic return.

For example, in Minnesota, corn for silage is often planted after alfalfa and pressure from corn rootworm is typically minimal in the first year after alfalfa. That’s because, in Minnesota, the majority of corn rootworm eggs are laid in corn and the larvae generally hatch within two years.

However, you should consider the need for transgenic resistance to European corn borer in you fields and the herbicide resistance traits needed for your cropping system.

Agronomic considerations

Other important agronomic considerations include tolerance to drought and disease. Selecting a hybrid with a high rating for drought tolerance may be useful on droughty soils, in dry regions or in a lower-rainfall area where a previous crop of alfalfa has depleted subsurface soil moisture.

Standability is less important for silage hybrids than grain hybrids due to the earlier time of harvest.