Fall is a great time to test feedstuffs for nutritional value

Published on Mon, 11/21/2016 - 3:19pm

By Joseph W. Ward, Ph.D.

One of the best ways to provide nutritionally balanced rations for your livestock is to test your on-farm feedstuffs then balance the rations based upon your feed testing results.  Fall is a great time to do this testing.  Knowing the nutritional values of your corn, soybeans, hays and silages removes a lot of the guess work.  This prevents costly underfeeding and overfeeding of feed nutrients.  Feed rations can be balanced for all ages and stage of production nutritionally for optimum animal performance.

How to feed test: Proper sampling of feedstuffs is paramount for nutritional testing to have value.   It is important to have a representative sample of the feedstuffs that you send to an analytical laboratory for testing.  Samples submitted must be clearly labeled.  Record on the sample bag in permanent marker, the feedstuff name, date crop was harvested, date sampled, farm name, and lot number/cutting. It is a good practice to write a brief description of each sample you collect and keep these records in a permanent location for future reference. Sample and analyze each lot or cutting separately that are to be fed to your livestock is usually the most cost-effective route.  Here is what you need to know when testing feed:

How to sample:  It is very important that you take a representative sample of each cutting, silo, bunkers, etc.   The nutritional analysis is only as good as sample you take. Taking samples correctly takes time.  Allow yourself ample time to collect subsamples of hay, silage, etc.  Using a coring probe with a sharp tip makes sampling easier and quicker to perform. Forage and grain core samplers may be available for loan from your area extension specialist, nutritional consultants, or other producers.  Unstable silage can change during shipping.  Place samples in a plastic bag, remove as much air as possible and seal tightly. Vacuum sealing is highly recommended for samples that are unstable, being shipped long distances or for analysis that are susceptible to changes during fermentation.  You may want to consult with your feed testing laboratory for direction on how to properly handle the samples that are being tested for mold, yeast and/or toxins.   

Sampling every hay bale is best but not practical.  Select 7 to 15 bales for each lot (cutting) for testing. Hand-grab samples will not be representative unless the feedstuff is already will-mixed prior to sampling.   Mix all the collected subsample for each lot in a clean 5-gallon plastic bucket.  Mix the entire sample thoroughly, and then pour it on a clean piece of paper or plastic, Divide the sample into four equal parts (quarters), saving two opposite quarters including all fines.  Place the sample in a gallon plastic bag, exclude air and seal tightly.  Make sure you have properly labeled the sample bag using a permanent marker on the outside of the plastic bag. 

For grain and bulk feedstuffs, use a grain probe and collect at least 5 to 7 subsamples from various locations in the bin or truck.  A probe that penetrates at least three-fourths the  depth is best.  Mix the subsamples and reduce the sample size if necessary to about a quart.  Label the contents of the plastic bag using a permanent marker, exclude air and seal.

When collecting silages, balage and other wet feedstuffs, make sure you keep the sampling container closed to prevent moisture loss.  Mix the samples thoroughly and use the quartering method to reduce the sample size between a quart and gallon.  Place the sample in a gallon plastic bag, exclude air and seal tightly.  Make sure you have properly labeled the sample bag using a permanent marker on the outside of the plastic bag. Record the information for future reference.

Have the right tools: A coring probe will provide a more accurate sample than a hand-grab sample. Several probes are available, and all have advantages and disadvantages. Having a hay probe with a sharp cutting tip, a heavy-duty portable electric drill, as well as power to drill into the feed source, is essential and saves a lot of time sampling. Have plenty of plastic quart and gallon size plastic bags, a 5-gallon bucket for mixing samples, a permanent marker for labeling and clean mat or paper to pile the sample on a clean surface for quartering the mixed subsamples.  Quartering the sample allows for reducing the sample size while maintaining a representative sample with the proper distribution of particles of all shapes and sizes for testing.

How many to sample: Sampling every bale is best but not practical. Classify the feeds by type, cutting, field, etc. Then core representative bales and empty the samples into the sample container. Core at least seven bales, but 15 to 20 bales would be better.

Using a hay probe, collect a subsample for each bale by coring in the end of square bales and in the circumference of round bales.  Core in an upwards direction to reduce moisture spoilage.  Place all the subsamples in a 5-gallon clean plastic bucket and mix well.  Fill a quart size zip lock bag with the well mixed sample until it’s ¾ full.  Exclude excess air, seal tightly and with a permanent marker write the descriptive information listed above on the bag.

Send the collected feedstuff sample to a feed testing laboratory:  Consult with your area extension specialists or feed representative for feed testing laboratories near you.  Also, the National Forage Testing Association maintains a list of certified testing laboratories.  Remember hay and silage samples are perishable.  Ship or deliver samples to the laboratory as soon as possible to prevent moisture loss and microbial deterioration of the sample.

What to test for: Feeds can be tested for many things. The most important tests for ration balancing are dry matter, crude protein, acid detergent fiber (for determining energy content), calcium, phosphorous, magnesium, potassium and sulfur. Most laboratories provide an array of packages for testing forages and grains.  Samples may be analyzed using either NIRS (near-infrared spectrophotometry) or wet chemistry methods.  It’s best to choose the wet chemistry for mixed forages and mixed grain samples.  Your feed testing laboratory and nutritional consultant can assist you in choosing the best analytical testing methods for your sampled feedstuffs.

Using lab results: The laboratory results of properly sampled feedstuffs can provide valuable nutritional information about your feeds.  Knowing the nutritional value of your feedstuffs takes the guess work out of balancing rations for your livestock. Overfeeding or underfeeding livestock can be very costly compared to the cost of testing your feedstuffs.  It is very important to implement your feed test results in your ration balancing programs as soon as you receive the results to properly feed your livestock.  Sampling feeds tells us the nutritional value of the feed but it serves no purpose until it is used and implemented in your feeding program to properly balance your livestock rations.


The author, Joseph W. Ward, has a BS in Animal Science, a MS in Animal Nutrition from Purdue University and a Ph.D. from Oklahoma State University in Ruminant Nutrition.  Born and raised in Indiana on a livestock farm, Dr. Ward has consulted in Europe, the Far East, Oceania, and South Africa.  He has been active in animal production and animal feed manufacturing/processing since the early 80’s.  He is an organic inspector for crops, livestock and processing.  Currently, he serves as North America Product Manager for Phileo Lesaffre Animal Care. Dr. Joe can be reached at j.ward@phileo.lesaffre.com.