Navigating the BMR Transition: What Neutral Research Says and How to Win the Switch
Across the industry, more dairies are asking the same question: If we move away from brown-midrib (BMR) corn silage, what happens to cow performance and the bottom line?
The good news: there’s a clear body of neutral research that shows why BMR works, where it can cost you, and how to transition successfully to high-digestibility, non-BMR silage without giving up milk.
Below is a concise tour of peer-reviewed studies and university guidance, followed by a practical transition playbook you can use with your nutritionist and forage team.
What the research consistently shows
1) BMR improves fiber digestibility—and often bumps milk
Decades of controlled trials have documented that the bm3 mutation lowers lignin and increases fiber digestibility (NDFD), which can lift intake and milk. Oba & Allen (University of Michigan) reported that cows fed bm3 corn silage had greater NDF digestibility and produced more milk than when fed an isogenic control, at a fixed inclusion rate near 45% of diet DM.
Subsequent controlled comparisons and reviews reached similar conclusions: in many settings BMR diets raise DMI and milk yield versus conventional silage. A university review summarizing trials across herds found milk yield gains around +1.7 kg/d for BMR diets in several studies.
Other controlled Latin-square work (Kung et al.) also observed higher milk for BMR vs. normal silage across cutting-height comparisons.
And more recent trials confirm the trend: bm3 silage typically increases fiber degradability and can increase DMI and milk yield.
Bottom line: the NDFD advantage of BMR is real and repeatable across many studies.
2) The trade-off: yield drag and agronomic risk
Multiple extension sources caution that BMR’s fiber advantage is frequently offset by lower DM yield (often quoted in the 10–20% range), plus increased lodging and foliar disease risk—factors that matter at whole-farm scale.
In other words, BMR can win in the cow but lose acres in the field—especially in stressful growing seasons or where standability is critical.
Bottom line: if the yield penalty or standability losses exceed the milk gain, BMR’s whole-farm economics can turn negative.
3) Non-BMR can match milk when starch and overall digestibility are managed
A useful nuance in the literature: processing, moisture at harvest, and kernel/plant characteristics influence starch availability and total-diet digestibility enough to narrow or eliminate BMR’s milk advantage.
For example, Ebling & Kung compared processed conventional silage to unprocessed and processed BMR silage; once harvest practices were optimized, differences in intake, digestion, and milk narrowed materially.
Meta-analyses and management trials also show that very high DM at harvest reduces starch digestibility and milk, independent of hybrid; correct processing (1–3 mm) and target DM improve total-tract starch digestibility and milk output.
Bottom line: with the right non-BMR genetics (high rumen-available starch + good NDFD) and tight harvest/ensiling control, you can preserve milk while avoiding yield drag.
A practical playbook for transitioning away from BMR
The research paints a balanced picture: BMR’s fiber advantage is real, but its agronomic costs are also real. If you’re planning a pivot toward non-BMR while protecting performance, here’s a proven framework to follow.
1) Choose non-BMR genetics for cow outcomes, not grain traits
When you evaluate conventional hybrids, lean on the same performance drivers that make BMR successful in the cow:
Higher NDFD: Seek non-BMR hybrids that test strongly for NDFD in your region; several programs now select specifically for dairy NDF traits (not just tonnage).
Soft/rumen-available starch: Kernel endosperm type matters. Softer, more floury starch increases rumen availability—critical if you are reducing purchased grain. (Trials consistently show starch structure plus processing drive energy capture.)
Stay-green/plant health: A wider, safer harvest window helps you hit target moisture and protect starch/NDF digestibility in variable weather.
2) Manage harvest for digestibility (the great equalizer)
Numerous neutral studies agree: harvest decisions can make or break milk, independent of hybrid.
Moisture target: Aim for ~65–70% whole-plant moisture. Very high DM (too dry) drops starch digestibility and milk.
Kernel processing: Tight rolls (≈1–3 mm) improve total-tract starch digestibility versus coarse or unprocessed material.
Cutting height & effective fiber: Balance energy and physically effective NDF for rumen stability; higher cuts can increase energy density, but don’t solve poor processing or moisture misses.
3) Use ensiling time strategically—then validate with data
Starch digestibility increases during storage as zein proteins break down; optimizing time in the pile (and monitoring VFA/temperature) helps conventional silage “catch up” on energy capture. Use wet-chemistry labs to track 7-h and 30-h starch/NDFD and adjust inclusion rates accordingly. (University methodologies such as Milk2016/Milk per Ton/Milk per Acre are appropriate benchmarks for value.)
4) Keep the economics honest with IOFC
The right metric for the transition isn’t seed cost or acres alone—it’s Income Over Feed Cost (IOFC). When non-BMR silage allows higher forage inclusion, lowers purchased grain, and maintains milk, IOFC rises even if milk is flat to slightly lower. University extension tools and standard models are designed for exactly this comparison.
What to expect as you switch: three realistic scenarios
High-forage, well-managed harvest
With non-BMR genetics selected for starch availability and NDFD—and with correct moisture and processing—milk is typically maintained, grain purchases drop, and IOFC improves. (This is the most common successful outcome reported in neutral comparisons where management is dialed.)Excellent fiber digestibility environment
In very high-producing herds chasing top-end DMI, BMR can still out-milk non-BMR by ~1–2 kg/d, but only when yield drag doesn’t penalize whole-farm inventory. If acres are tight or harvest risk is high, the BMR advantage may vanish in the budget.Stress year / variable fields
When weather raises lodging/disease risk or tightens the harvest window, non-BMR with stronger agronomics often wins on consistency, protecting both inventories and ration stability—not to mention labor sanity. Extension cautions about these BMR risks are consistent across regions.
A balanced takeaway
Why BMR works: Higher NDFD → higher intake → more milk (in many studies).
Where it struggles: Yield drag (10–20%), lodging/disease risk, and shorter product lifecycles in some programs.
How non-BMR succeeds: Choose dairy-focused, high-digestibility genetics; nail moisture and processing; use storage time and lab data; measure outcomes with IOFC.
If you’re planning your “life after BMR,” the science offers confidence: you can keep milk moving with non-BMR hybrids—and, with the right forage management, often improve whole-farm economics.