Is a Probe Necessary to Test Horse Hay?

Is a Probe Necessary to Test Horse Hay?

Using a hay probe or corer is the best way to collect a sample for testing.

Photo: Courtesy Dr. Dennis Sigler

Q. I just got my hay in for the year and have decided I’d like to get it tested, but I don’t own a hay probe. Do I really need one, or can I take some handfuls of hay to submit to the lab?

A. When having a hay analysis performed, your goal is to get data that represents all the hay of that type in your stack. Hay within a stack will have grown across the field, and growing conditions can vary depending on soil conditions, sunlight exposure, etc., and these factors can result in nutrition content variation bale to bale. The variation shouldn’t be too great, but some will exist. For this reason, you want to submit a sample for analysis that captures the variation that exists within the hay stack.

The data you receive from the lab is only as good as the sample you send them. Therefore,  your representative sample needs to capture potential variation between bales and across the stack.

Obviously, the more bales you sample, the more representative your data will be. However, it’s not realistic to sample every bale in a stack unless you only have a very small number of bales. At that point, testing the hay might not make much sense because you might have fed most of it by the time you get lab results back.

Using a hay probe or corer is the best way to collect a sample. A hay probe is a long metal tube often connected to a power drill that is inserted into the short end of the bale to a depth of about 18 inches. The core of hay that has been cut by the tube is emptied from the tube into a clean dry container or locking bag, and the process is repeated on another bale. To do this well, there are two important considerations:

  1. You need a drill powerful enough to insert the probe far enough in to the bale. I have killed more than one battery-operated drill coring hay!
  2. It’s important to insert the probe into the short end of the bale so you get cross-sections from several flakes. Ideally, you should take cores from 15 to 20 random bales from your stack. This will help ensure the data you receive from the lab represented all the hay in your stack as closely as possible.

The problem with grabbing handfuls is that it’s difficult to insert your hand very far in to a tightly packed bale, and you really need to pull from the center of the bale. It’s also almost impossible to reach in to a bale from the short end and collect a handful that represents multiple flakes in that bale. Reaching in to the same bale and taking hay from several places within the bale results in a very large amount of hay. Do this on 15 to 20 bales and you will have a huge volume of hay—far more than the lab needs for analysis.

Video: How to Sample Hay for Analysis

Learn how and why to sample your horse's baled hay for nutritional analysis at

Depending on the type of hay, you might find it difficult to extract your hand from a bale and still have the entire plant in your hand. Some hays, such as alfalfa, lose their leaves very easily, especially when handled roughly. The carbohydrate fraction and protein content in stems versus leaves can be quite different, so losing leaves might result in a sample that’s not representative of what your horse will actually eat and, therefore, are of little value.

Take-Home Message

It’s possible to do a good job taking samples from bales by hand, but it takes care. Using a probe is an expense, but you’ll get much better data. And, if you’re someone who buys large amounts of hay at one time, a probe is an excellent investment.

About the Author

Clair Thunes, PhD

Clair Thunes, PhD, is an independent equine nutrition consultant who owns Summit Equine Nutrition, based in Sacramento, California. She works with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the United Kingdom Pony Club. Today, she serves as the regional supervisor for the Sierra Pacific region of the United States Pony Clubs. As a nutritionist she works with all horses, from WEG competitors to Miniature Donkeys and everything in between.

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