Brown Midrib and Leafy Corn Silage Performance + A New BMR Economics Calculator

Commercial corn hybrids grown in Wisconsin are often marketed to dairy farmers as "silage-specific." In the UW Corn Performance Evaluation Trials, conventional hybrids have similar yield and quality as bio-engineered corn hybrids. However, we often see yield and quality differences between silage-specific "leafy", brown midrib (bmr), and conventional/bio-engineered hybrids. In addition, companies often market newer 3rd- and 4th-generation silage-specific hybrids implying that breeding progress has improved performance.

Brown midrib corn (picture above) has a distinctive brown midrib on the corn leaf. These hybrids typically have greater digestible energy in the stover (stalks and leaves). Leafy hybrids have 2-5 more leaves above the ear compared to conventional hybrids.

Figure 1 shows the relationship between Milk per Acre (yield) and Milk per Ton (quality) for bmr and leafy hybrids. In most years leafy hybrids tend to be average for Milk per Acre and below average for Milk per Ton. BMR hybrids tend to be below average for Milk per Acre and above average for Milk per Ton. For either hybrid type there does not seem to be a trend for newer generation hybrids.

Figure 1. Mean Milk 2006 relative performance of Brown midrib and Leafy hybrids in the UW Corn Performance trials. The origin is the overall average of all hybrids tested between 1995 and 2018 (N= 38,664 plots). BMR plot total= 623 and Leafy plot total= 1538. Difference = overall hybrid average – trial average, Code above symbol= Year

Both bmr and leafy hybrids have lower than average starch content compared to the overall mean of all hybrids in the trial ultimately affecting both yield and quality (Figure 2). Leafy hybrids have average ivNDFD, while bmr hybrids have above average ivNDFD.

Figure 2. Mean starch and ivNDFD relative performance of Brown midrib and Leafy hybrids in the UW Corn Performance trials. The origin is the overall average of all hybrids tested between 1995 and 2018 (N= 38,664 plots). BMR plot total= 623 and Leafy plot total= 1538. Difference = overall hybrid average – trial average, Code above symbol= Year

Many research reports have concluded that bmr corn silage increases milk production in cows. Our data consistently shows higher Milk per Ton, but lower Milk per Acre yield due to lower forage yield primarily due to grain yield. Since there is typically no premium paid for higher quality corn silage, I have often said, "Buy all of the bmr corn silage you can buy, but be careful about growing it on your farm." Breeding progress has likely improved silage-specific corn hybrids, but there is a corresponding genetic improvement going on with conventional and bio-engineered hybrids as well.

The BMR Corn Silage Calculator: What are the economic trade-offs for yield and quality?

To better understand the economic effect of bmr corn in dairy operation, Dr. Randy Shaver et al. have developed a spreadsheet that can be downloaded here and here. This MS Excel spreadsheet calculates milk production of brown midrib (BMR) corn silage hybrids versus conventional  hybrids. The spreadsheet calculates differences based cow herd size. Dr. John Goeser (Rock River Labs and adjunct UW faculty) has produced a video explaining how to use the spreadsheet here.