By Christine Gelley, Agriculture and Natural Resources Educator, Noble County Ohio State University Extension
As hay making season ends and hay feeding season approaches, it is time to remind everyone that feeds hay how important getting a hay test completed is for deciding how to feed your livestock this winter. A hay test will cost you far less than the cost of a single round bale. The results you get back will give you the information you need to decide what type of feed and how much you will need to purchase to keep your animals productive until good pasture is available to graze again.
If you have never done a hay test before, Extension is here to help you. We have tools you can borrow and personnel to help with consultation. Here are the steps of how to take a hay test.
- Subsamples can be collected with a Hay Probe and a clean bucket or with your hands and large scissors.
- Select 10 random bales from the same field and cutting.
- Drill/Reach into the center of the bale, from the wrapped side, not the exposed side, and remove a probeful/handful of hay.
- Hold over the bucket and empty/cut 4-inch to 6-inch long pieces.
- Repeat the above until you have subsampled all 10 bales.
- With your hands, gently mix up the pieces in the bucket.
- Fill a quart plastic bag with your composite sample.
- Press out all the air and seal the bag.
- Label the sample bag with your name and sample ID.
- Complete the Sample Information Form for the lab you wish to use.
- Return the Hay sample(s) along with the Sample Information Form.
- Go over the results of your hay test with a professional familiar with how to feed your class of livestock.
When you get your hay test back there are some key terms that are important to understand for interpretation. Forage nutritive values analyses from the laboratory often include the following factors:
- Dry matter (DM) is the percentage of feed that is not water.
- Crude protein (CP) measures both true protein and non-protein nitrogen.
- Adjusted crude protein (ACP) is a value corrected for heat damage. It should be used in place of crude protein.
- Neutral detergent fiber (NDF) measures the structural part of the plant, the plant cell wall. NDF gives “bulk” or “fill” to the diet. Therefore, lower numbers indicate higher quality.
- Acid detergent fiber (ADF) primarily consists of cellulose, lignin, silica, insoluble crude protein and ash, which are the least digestible parts of the plant. Low ADF is preferred because it indicates a higher energy value.
- Total digestible nutrients (TDN) represent the total digestible components of crude fiber, protein, fat, and nitrogen-free extract in the diet.
- Relative Feed Value (RFV) predicts the animal intake rate and energy value of forages according to the amount of digestible dry matter (DDM) and potential dry matter intake (DMI). It is calculated by taking DDM multiplied by DMI and then dividing by the constant 1.29 and communicated as a percentage in comparison to the feed value of full bloom alfalfa, which has a RFV of 100.
- Relative Feed Quality (RFQ) is another metric for ranking forage quality. It is similar to relative feed value but is determined from an improved equation for indexing grass forages because it considers fiber digestibility in the calculation. The calculation for RFQ is the percentage of dry matter intake (DMI) multiplied by the percentage of total digestible nutrients, the sum of which is then divided by the constant 1.23 (this divisor creates a similar mean and range to RFV, which RFV and RFQ to be compared).