by Daniel Olson, Founder of Forage Innovations
One of the largest breakthroughs in corn silage quality has been the identification of the Brown MidRib gene in corn and the development of hybrids that carry the gene. BMR hybrids generally have better fiber digestibility and lower levels of UNDF (undigestible fiber) then their conventional counterparts. This can allow dairy farmers to feed more forage in their diets and to potentially get higher milk production. While the benefits of BMR corn are well documented, I have actually been seeing a shift away from BMR corn in the last few years. This article will cover a few of the questions that you should answer to determine if BMR is a good fit for your farm.
#1: How much corn silage do you want to feed?
A dairy cow has a minimum and a maximum amount of uNDF that she can utilize. Too little can impact rumination and therefore animal health . Too much can limit DMI and production. BMR corn has about 2% less uNDF240 (as a percent of DM) than conventional corn hybrids. If you are planning on feeding 80%+ of your forage as corn silage, BMR may benefit you because it will help keep the uNDF in a optimum range.
#2: Will you be feeding much alfalfa in the diet?
While most rations are 6-7% uNDF240, average quality alfalfa may be 15%+ uNDF240. This can make it very hard to keep the overall ration low enough in uNDF. BMR can help with that and pairs nicely with alfalfa in a ration.
#3: Do you have above average soil fertility and adequate moisture?
While BMR corn may average 10-15% less yield than conventional corn it is not as consistent. That means on good ground with adequate moisture the yield drag may be negligible, but when BMR fails, it generally does so spectacularly. It is just not a great agronomic fit on farms that are drought prone or have more marginal soils.
#4: Do you have a large land base?
The challenge with heavy BMR corn diets are that it not only yields less, intakes usually go up. High forage diets are wonderful if we actually have the forage but if those inventories are tight it can really be a challenge to make things work. The other issue is that BMR corn does best on a tight rotation with minimal corn-on-corn. If the whole farm is planted in corn it can make rotation and agronomics difficult.
#5: Can you wait to feed it?
While Brevant’s Unified and the Kingfisher BMR are floury, the majority of BMR corn has fairly flinty (vitreous) starch and should ferment 3-6 months before feeding. Because BMR tends to have a little lower starch levels then convention corn, it is important to get the most out of the starch that it has been produced.
In summary, while BMR has benefited many farms, it is not magic or a requirement to gain high milk production or profitability. On my client farms that don’t use BMR corn, we focus on bringing digestible fiber into the diet with other forages like warm and cool season grasses and small grains. These forages can fill this requirement of the ration while keeping uNDF levels down. They also give us crops to utilize manure and help with a healthy crop rotation.