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Hay Analysis Part II: Judging Quality

Deciphering the analysis results

Hay analysis So you've had your hay tested and have the results back. Now what? What does it all mean? There are a number of ways to judge the quality of your hay, but some of the easiest results to look at to assess quality are the relative feed value (RFV), digestible energy content (DE), neutral detergent fiber (NDF) and acid detergent fiber (ADF) content, water soluble carbohydrates (WSC), starch and crude protein (CP).

Relative Feed Value

Relative feed value is a method of measuring hay quality that takes into account the expected consumption and digestibility of the hay as a factor of its maturity. The system was designed for use in ruminants however it still has use for assessing hay for horses. As the RFV increases over 100 quality increases and an RFV below 100 indicates lower quality. Comparing RFV’s of different hays is an easy way to quickly assess which is of higher quality.

Digestible Energy

Digestible energy (DE) for horses is not calculated by every lab so ensure that you send your sample to a lab that performs equine-appropriate analysis. The DE per pound will indicate how many calories per pound your horse will receive. Performance horses, brood mares and youngstock will benefit from hays with higher DE values (more than 0.9 Mcal/lb) versus the easy keepers who may benefit from a lower DE (less than 0.9 Mcal/lb). By feeding easy keepers lower calorie hay you will be able to keep more hay in front of them which is good for reducing boredom and for their gastrointestinal health.

Crude Protein

Crude protein (CP) in the hay is a crude estimate of the actual protein content.  Legumes typically have high crude protein contents (18.5-23.5%) while grass hays have moderate levels (7-15%) with grain hays generally having the lowest (5.5-11%). Level of maturity at cutting impacts protein content with more mature hays having lower crude protein.  If a large enough amount of low protein hay is fed it is still possible to meet a horse’s protein needs.  Alternatively when feeding a lower protein grass or grain hay a legume hay may be added to the ration to increase the overall protein level.

Young growing horses have the greatest need for protein in their ration, again making them candidates for the higher quality less mature cuttings.  While it is possible to meet most horse’s crude protein needs even when feeding a lower protein hay, the quality of that protein may not be adequate to meet all of their requirements and it may be necessary in those situations to feed a source of good quality protein such as those found in many commercial ration balancing feeds.

Next time

In a future blog post we will discuss the carbohydrate fractions seen on a hay analysis and how to determine whether your hay or forage is a good choice for your horse especially those with metabolic issues.

Creative Commons License
How to Sample Your Hay for Analysis Part II by Dr. Clair Thunes PhD is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.
Based on a work at

Published: Oct 21, 2015
Last Modified: 
June 2, 2024 @ 12:04 am

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