Beware of nitrates this spring

Posted on March 25, 2020 in Dairy Performance
By Dr. Michelle Chang-Der Bedrosian
We often associate nitrate concerns with drought-stressed plants, but very wet conditions can also stress plants and cause them to accumulate nitrates.  Furthermore, high nitrate levels aren’t just a concern during the harvest season.  We are hearing reports of silages with higher-than-normal nitrate levels this spring.

Silo gas
Last year’s tough harvest season resulted in some crops going into the silo frozen, which means they did not ferment.  As the weather warms, they begin to “thaw” and undergo a fermentation, which also means there is risk for silo gas formation.  Please, be careful!  Follow the same steps now to avoid silo gas poisoning as you would during the harvest season.  Click here for a refresher on silo gas safety.

Nitrate issues in dairy cows
Dr. Limin Kung, University of Delaware researcher, reminds us that “problems with nitrates are dictated by two factors:

  • Total nitrate consumed
  • The amount of nitrate consumed in a single meal”

It may be wise to test for nitrate if you notice weight losses, reduced milk production, abortions or reproductive issues.  In acute cases in dairy cows, nitrate is absorbed into the hemoglobin in red blood cells instead of oxygen, leading to respiratory issues, blueish gums and brownish blood.

Reading nitrate reports
Laboratories may report nitrate as nitrate-N or nitrate ion.  Pay close attention to how it is reported from your laboratory.  Also make sure it is reported on a total dry matter intake basis.  Kung offers these guidelines for total nitrate intake for ruminants:

What do I do if I have high nitrate levels in my feed?

  • Manage the diet:  Gradually incorporate the high-nitrate feed into the diet to allow adaptation, dilute the feed and/or consider feeding more vitamin A.
  • Manage the feeding:  Feed the questionable feed in several small feedings during the day to avoid large doses.
  • Keep the rumen healthy:  Rumen bacteria can detoxify nitrates.  Keep the rumen healthy by providing adequate dietary carbohydrates to maximize microbial fermentation and degrade nitrates, avoid rapid changes in the diet, keep the herd healthy, consider a probiotic to boost rumen fermentation, and limit additional stress to the animal.

About the author:  Dr. Michelle Chang-Der Bedrosian is a Vita Plus forage products and dairy technical service specialist. Chang-Der Bedrosian earned her bachelor’s and master’s degrees in animal science at the University of Delaware. She continued there to earn her Ph.D. in animal and food science, specializing in forage research with Dr. Limin Kung. Her thesis research centered on the use of a protease to improve starch digestibility earlier in the ensiling process. A New Jersey native, Chang-Der Bedrosian gained much of her farm experience during her collegiate years, milking cows, working in a forage laboratory, and performing dairy research. Based in Madison, Wisconsin, Chang-Der Bedrosian’s responsibilities at Vita Plus include forage product research and development, dairy research, and dairy technical services.

Category: Animal health
Dairy Performance
Feed quality and nutrition