Can you feed reduced-lignin alfalfa with BMR corn? – Barry Visser, Vita Plus

Posted on February 1, 2019 in Forage Foundations
By Barry Visser, Vita Plus dairy technical specialist
High-quality forages are essential to maximize performance in lactating dairy cows, especially if your goal is to feed high-forage diets.  With the introduction of reduced-lignin alfalfa, some producers ask if pairing this product with brown midrib (BMR) corn will result in too much digestible fiber.

While controlled research on feeding both reduced-lignin alfalfa and BMR corn silage is limited, producers are having success with this strategy.  The decision and extent to move toward lower-lignin forages are farm-specific.

Fiber digestibility
A complex organic compound, lignin binds cellulose fibers, and hardens and strengthens plant cell walls.  Lignin content increases as plants mature and gives structural support to the plants as they become taller.  Lignification is most pronounced in older stems of mature plants and least pronounced in young, developing plants.  The increase in lignin in mature plants negatively affects forage quality and interferes with animal digestion rates.

In numerous controlled dairy feeding trials from multiple locations and years, BMR corn silage nutrient composition improvements have translated into greater dry matter intake (DMI) and milk yield.  Agronomic and yield drag concerns remain in certain locations and growing conditions.  Even so, BMR corn silages have become the preferred hybrid choice for many high-producing dairy herds.

More recently, reduced-lignin alfalfa varieties have become commercially available. Alfalfa forage with reduced lignin will digest faster in the rumen, allowing for increased intake.  This increased rate of digestion can result in greater milk production.

Harvest flexibility
Alfalfa forage yield is generally highest at full maturity (full bloom), but forage quality decreases with plant maturity, generally due to the increased lignin content that accumulates as plants mature.  The downside to cutting at earlier plant maturities and imposing shorter intervals between cuttings has been reduced alfalfa dry matter yield per acre, more cuttings (and harvest costs) per year, and compromised stand longevity.

One option with reduced-lignin alfalfa is to simply capture higher-quality forage through greater neutral detergent fiber digestibility (NDFD) at your current harvest maturity and cutting frequency.  Another option might be to widen the cutting interval to capture more yield per acre of alfalfa similar in quality to normal-lignin varieties.  The latter approach can eliminate a cutting and save associated harvest costs.

Reduced-lignin alfalfa varieties show 5- to 15-percent reductions in lignin content, and up to 15-percent improvements in NDFD compared to normal-lignin varieties in research trials.  By contrast, NDFD is typically about 20 percent greater for BMR corn hybrids relative to non-BMR hybrids.

Ration considerations
Usage rates for reduced-lignin forages depends on several agronomic factors, including land availability, input costs, rental agreements, geographic locations and soil types.  Availability and cost of fibrous byproduct sources, such as beet pulp, soyhulls and corn gluten feed, can also play into this decision.  These byproducts can be as much as 60 percent greater in NDFD compared to normal-lignin forages.  Although forages have market value, these byproducts are purchased feeds and can present some handling and logistical concerns.  Utilizing BMR and reduced-lignin alfalfa can provide the option to feed higher levels of forages while maintaining desired NDFD levels in your lactating dairy rations.

Significant attention to details may be necessary in situations with major lignin reductions and NDFD increases.  Changes may include increasing physically effective NDF through greater dietary forage and forage-NDF content, reducing dietary starch content, and/or lengthening silage chop settings.

Cow-side observations of manure consistency, cud chewing and rumination are valuable.  Reduced milkfat content or feed efficiency, measured as DMI relative to level of milk production, can be good group or herd diagnostic indicators that these types of interventions are necessary.

Determine the best fit for your operation
Reduced-lignin alfalfa and BMR corn silage can be combined effectively to feed high-production dairy cows.  Work closely with your nutrition and agronomy advisors to determine what is the most strategic and economical combination on your dairy.

This article was originally written for Barry Visser’s January column in Dairy StarClick here for the original article.

Category: Crop varieties
Feed quality and nutrition
Forage Foundations