Alternatives to brown mid-rib corn silage

Brown midrib corn silage was first introduced to the dairy industry nearly 30 years ago. Compared to conventional corn silage, BMR’s lower lignin content made it a tool to increase fiber digestibility, typically resulting in greater dry matter intakes and increased energy-corrected milk production. These results have been noted on farms and in numerous controlled dairy lactation feeding trials conducted over multiple locations and years.

Corteva — the parent company of Pioneer, Brevant and Dairyland Seed — announced this spring that BMR offerings will begin phasing out and the final year of BMR sales will occur no later than the 2030 growing season. Farms that have traditionally used BMR varieties have already begun looking for alternatives.

While BMR has been a valuable tool on many Midwest dairy farms, it also had some drawbacks. Although the BMR genetics improved over the years, agronomic traits such as standability, stalk integrity and reduced yields remained a concern in certain locations and growing conditions. This led to additional acres needed to harvest adequate amounts of corn silage, which was especially challenging when land base was limited. In addition, growing BMR corn silage typically has been more expensive than conventional corn silage. This often led to a bigger discussion of whole-farm profitability and income over feed cost.

Improving fiber digestibility

Several farms have found success in improving the fiber digestibility of their conventional corn silage by controlling the planting population. Research at the University of Wisconsin showed a significant improvement in fiber digestibility with 30,000 plants per acre compared to 35,000 or 40,000 plants per acre. It should be noted that quality improvement responses may not be consistent across different hybrids. Soil type, fertility and growing conditions may also affect this response.

Increased cutting height at harvest can also have a positive impact on silage quality. The highest concentration of lignin in the corn plant is in the bottom portion of the stalk. A complex organic compound, lignin binds cellulose molecules and hardens and strengthens plant cell walls. Lignin content increases as plants mature and gives structural support to the plants as they become taller. The increase in lignin in mature plants negatively affects forage quality and interferes with animal digestion rates.

Leaving more of the stalk in the field increases the harvested silage’s concentration of available energy to the cows by increasing digestible fiber and starch concentration in the harvested silage. These quality benefits come at the expense of lower yields, which brings us back to one of the limitations of BMR corn.

The range of fiber digestibility between BMR and conventional corn silage has narrowed over the years. New hybrids continue to be developed to maximize yields while still improving plant digestibility. In addition, newer technology such as short-statured corn hybrids gained some attention this past growing year as they appeared in some corn plot comparisons. Short corn has the same number of leaves and similar-sized cobs as conventional hybrids. Although yields may be lower, short corn is likely to see an increase in fiber digestibility and starch concentration compared to conventional hybrids. Keep an eye out for additional research on short corn moving forward.

If you are an avid BMR user for some or all of your corn silage needs, you should begin exploring alternatives now to give yourself time to determine which options best suit your system. Allocating some of your BMR acres to alternative options would allow you to do some on-farm evaluation from both agronomic and animal performance standpoints. Work with your agronomist and nutritionist to determine the best strategy for your operation.

Barry Visser is a nutritionist for Vita Plus.