There is more to sampling hay than grabbing a handful of grass or a flake from a bale and sending it off to a lab for testing. So, what is the right process for testing hay? How should a sample be collected? How many bales should be sampled? We will break it down for you in a few easy steps.

1. Identify a single “lot” of hay A lot of hay is the hay of a single variety that comes off a single field in a single cutting. If your hay comes from multiple fields, you have several different types, or you have more than one cutting from the same field than those are all separate lots of hay and should be sampled separately. Very large lots of hay (over 200 tons) may need to be split into two lots.

2. Sample at the right time Freshly baled hay undergoes some changes, particularly moisture loss called “sweat”. During sweating hay can heat up due to microorganism activity, which reduces th e moisture content of the hay and therefore increases dry matter content. The sugar content of the hay is also affected during sweating. Hay can sweat from a few days to weeks, and generally becomes stable once it reaches around 90% dry matter content. It is best to wait a few weeks before testing the hay to allow for this sweat period to finish.

3. Use proper tools and proper technique Hand grab samples just aren’t as accurate as a proper core sample. Choose a sharp coring device 3/8”-3/4” in diameter. Sample the bales at a 90° angle to the center of the bale and 12”-18” inches deep. The goal is to sample across as many layers of hay as possible to get a good representative sample. Sample in-between the baler twine to help keep the corer sharp and prevent plastic contamination. We love the hay corers from Star Quality Samplers.

Core probes collect a representative sample of stem and leaf

4. Sample at random and take enough cores

Walk around your stack and sample 20 bales at random. Again, the goal is for the best representative sample possible. Don’t pick or choose bales based on how “good” or “bad” they look. Make it as random as humanly possible.

The “gold standard” number of core samples is 20. This number is the same no matter what size and shape your bales come in. If you only have 20 bales or less than take one core from each bale.

Image: Variation between cores in a "uniform" stack (Putnam, N.D.)

5. Sample a good size and handle right

After sampling 20 bales you should have about a ½ lbs, or 227g of sample. Too small of a sample will not be as representative, and too large a sample can be difficult to handle in the lab. Seal the sample in a plastic bag and protect it from both heat and freezing temperatures. Double bagging is always helpful. Don’t let the sample get too much sun exposure, this can damage the sample and affect your results. Send the sample to the lab as soon as possible.

6. Choose a NFTA-Certified Lab

Not all labs are the same, and not all forage analysis packages test for the same things. You want a high-quality lab that participates in a 3rd party independent quality control program. The National Forage Testing Association (NFTA) independently sends blind samples to their participating laboratories 6 times per year and rates each lab on their performance. We use a NFTA-Certified laboratory for our forage testing, which can be used alone or in combination with our nutrition plans. We are also a NFTA Certified Hay Sampler and can sample your hay for you to make sure your hay is sampled right.

Six steps for proper hay sampling

How hot is too hot to ride?

Vitamin D in horses