Practice good feed management
If test results show worrisome nitrate levels in your corn silage, work with your nutritionist to adjust the ration accordingly. Here is some advice:
• LIMIT INCLUSION LEVELS. The amount of silage you should be able to feed depends upon the silage’s nitrate content and what animals you plan to feed it to. (For recommendations, please see “Is my silage safe to feed?” below.)
• GRADUALLY INTRODUCE THE SILAGE. Feed small amounts to start with and gradually increase levels over time.
• DILUTE IT. If possible, supplement with other forages to dilute the problematic silage. Work with your nutritionist on options that could work on your farm.
• CONSIDER ALTERNATIVES. Another option is to replace some of the corn silage with non-forage fiber sources. Some effective fiber is necessary in the diet, says Tamilee Nennich, assistant professor and extension dairy specialist at Purdue University. However, certain non-fiber feed sources, such as soybean hulls, corn gluten feed, cottonseed hulls and wheat midds, can help meet the cow’s fiber requirement. Straw or low-quality hay also may be an option.
Remember to consult with your nutritionist prior to altering the ration in any way.
Sampling drought-stressed silage
Proper sampling and analysis can help you make the most of drought-stressed corn silage harboring higher-than-normal nitrate levels. Here’s what you can do:
First, be safe. Do not take samples from the silage face because of both safety reasons and the inability to get a good sample, says Bill Weiss, professor and dairy extension specialist at The Ohio State University. Instead, take a few handfuls from several loader buckets over the course of a couple of mixer loads.
Put the handfuls into a 5-gallon bucket, mix well and dump the contents onto a clean floor or piece of plastic. Spread them out into a pie shape and divide the pie into quarters. Choose one quarter at random and put the contents into a re-sealable plastic bag. Follow your lab’s procedures for sending in samples.
If you store silage in silo bags, take five or six handfuls from the face, put them into a bucket and repeat the directions above.
It’s a good idea to sample periodically during the feeding period as silage is removed and put into the mixer, Weiss says. He recommends taking three or four samples over a short period of time (i.e., a couple of weeks) and using the average of the results to formulate the ration.
Is my silage safe to feed?
The following table shows recommended feeding guidelines based on nitrate nitrogen levels in corn silage: