High-nitrate forages: Beef specialist discusses options for feeding forages high in nitrate given drought

In a recent University of Nebraska-Lincoln (UNL) BeefWatch podcast, dated Sept. 1, Extension Beef Systems Specialist Mary Drewnoski highlights several options producers should evaluate as they consider feeding high-nitrate forages.

In the podcast, Drewnoski discusses grazing, silage and hay production of high-nitrate forages, as well as addresses a few other considerations for feeding livestock.

Grazing high-nitrate forage 

Drewnoski explains several reasons why grazing may be the best option for some producers, based on how cattle naturally graze. 

“Fresh forages will release nitrates at a slower rate than dry forages,” she explains. “If producers allow cows access to the whole field, the cattle are going to be selective. Cattle will naturally take off the leaf and the top of the plant first, and by doing so, they actually select plant parts that are lower in nitrate.”

When testing forages for nitrate, Drewnoski notes the nitrate content in a sample has the potential to be very different when compared to the actual intake of nitrates when fed. This is because microbes in the rumen can help detoxify the nitrate. Cattle can self-adapt to a high-nitrate feed, but it takes time for the rumen to build up the specific population of bacteria. 

“There’s really good data which shows even feeding two pounds of corn per cow can really reduce the risks of nitrates,” Drewnoski says. She also notes, when a high qualify forage isn’t available, one option would be grazing along with grain supplement to help increase energy content in the rumen to process nitrates.

“The rate of intake will be slower when grazing than eating from a bunk or eating off a bale as the amount in a bite is different,” Drewnoski says. She continues, the slower a forage is digested in the rumen, the more nitrate can be processed.

Drewnoski strongly discourages strip grazing because of reduced selectivity of the plant components. 

“This forces cattle to eat the lower part of the plant, which is typically higher in nitrates, right away so they can’t self-adapt,” she says.  

The goal with grazing is to allow two things to happen: slow and steady intakes and selective grazing. Drewnoski shares strip grazing doesn’t allow either of these to happen.

Harvesting forage for silage

            Previous research indicates when feeding silage with improper moisture content, there is less reduction in nitrates, and in some cases, no reduction due to an improper fermentation process. Harvesting nitrate forage for silage can work, Drewnoski explains, but silage production of high-nitrate forage must be managed well. 

            To avoid mismanagement, Drewnoski suggests allowing silage to sit for at least 21 days to ensure the proper fermentation phase has taken place. Through this process, the number of nitrates may decrease by 40 to 60 percent. 

            The challenge during the ensiling process is to enact good fermentation, in which Drewsnoski shares there are two variables: the right moisture content, which ranges between 65 percent and 70 percent, and packing the product in a way that allows very little oxygen. This process results in a loss of nitrates during ensiling.

Drewnoski adds, “The great thing about silage is that it makes it really easy to make a diet.” 

Forage harvested for hay

            “The last option can be the most difficult and toxic,” says Drewnoski. She expresses haying forage high in nitrates should be considered as a last resort. This is due to the rate of the intake and the rate of nitrates released in the rumen when hay is consumed, which is very rapid when hay is digested. 

Unfortunately, high-nitrate hot spots in the bale can also pose a risk. If possible, Drewnoski highly recommends producers grind and blend high-nitrate forages with low-nitrate forages to reduce risk of nitrite toxicity. 

Other considerations

Drewnoski finally discusses other resources in managing nitrates among these forages. Among the most important is testing all parts of the plant and each field. She also recommends producers refrain from feeding damp high-nitrate hay and keeping hay protected from rain. 

Lastly, Drewnoski shares producers can raise the cutter bar when harvesting hay and silage production. This may reduce the quantity, but increase quality and decrease nitrate content of hay. 

            For further questions or concerns regarding options on a management plan of high nitrate forages, Drewnoski recommends reaching out to local Extension Educators. Having a management plan can lower risks and be beneficial to both livestock and producers, Drewnoski concludes.

            Brittany Gunn is the editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.