Hay Analysis: Understanding Your Forage

December 9, 2023

By Sarah Griffiths, DCH

When your horse can’t have the perfect scenario (rotational field and forest turnout), the next best thing is good quality hay. Hay is the main source of essential energy, fibre, vitamins and minerals during the winter and, for some horses, all year round. Ensuring that your horse has access to good hay is paramount in preventing serious health issues. Poor hay can cause a number of problems including impactions/colic, poor hoof growth, poor body condition and other serious illnesses.

So how can you tell if your hay is making the cut? (pun intended!) Hay quality can vary greatly depending on the region it is grown in, species of grasses, stage of grass maturity, fertilization methods and harvesting, curing and storage methods. The first way to assess the quality of hay is by sight, smell and feel. The other way is to get your hay analysed. And, of course, how your horse is doing on it will be another indication. You should consider all of these factors carefully when deciding which hay to use and which supplements you may need to add.

You may get to know the grasses in your area to assess what species might be in your local hay. Fertilized grasses that are less mature are generally higher in nutritional value. When choosing hay, you will want to ask what types of fertilizers are used and if there are any insecticides, fungicides or herbicides applied at any stage of its growth. Your hay supplier should be doing soil testing to assess what minerals might need to be added to the soil prior to growing the hay. A good hay producer will be able to easily explain their process to you. Avoid all insecticidal/herbicidal sprays and, whenever possible, choose hay that has been fertilized with organic fertilizers instead of synthetics.

Judging Hay With Your Senses

Taking a close physical look at a hay source is important. You can learn a lot within 60 seconds of assessing it. Be sure you ask for a bale to be broken so you can see the inside and the outside of the bale. Here are the main traits to look for in your hay:


Some dark green color can (but not always) be an indicator of good quality. It means the hay was most likely cured correctly and that the nutrients have been preserved. Green color also means that there are enough important precursors for your horse to get enough vitamin A in their diet. Yellow, pale looking hay indicates that it might be old and low in nutritional value. Brown or black color hay was improperly cured and is likely mouldy – also look for white fluffy spores. Mouldy hay is toxic so avoid it at all costs!


Leafiness throughout the hay can indicate a higher quality, digestibility, and that it has been harvested at the optimal time (eg. not as a mature plant). This is considered to be a much more nutritious option than mature grasses but horse ancestry lends to the diet that fibre from mature plants might also be important. Course stems, seeds or flowers means the hay was harvested in its mature stage, is technically less nutritious and less digestible BUT we will discuss the possible benefits to feeding a variety of both types. Flowers will only be seen in mature legume hay. Seeds will be seen in mature grass hay.

Weeds and foreign material means the hay was poorly managed when grown. Weeds (particularly buttercup, thistle, and nightshades) should make up less than 10% of the forage and there should be no garbage or other foreign objects present. Dusty hay is a health hazard for you and your horse. It indicates that the hay is old and it should not be fed. Good quality hay is dry but not dusty.

Another note on alfalfa hay: Blister beetles are toxic and can infest mature alfalfa hay so do be sure to look for these.


It should smell fresh and sweet. If there is a musty smell, it indicates mould and should not be purchased or fed.

Understanding A Basic Hay Analysis

Getting your hay analyzed is an important part of getting to know the hay that you are feeding and how to complete it with other types of forage, herbs and supplementation. You cannot assess hay by sight alone and you cannot guess at the nutrient content without testing. Failing to obtain analyses on your hay could set your horse up for nutrient deficiencies and this problem is more common than most people know.

Hay can sometimes look very good but the analysis might still be lacking. Another thing to consider is that basic hay analyses don’t give you all of the answers but they do provide a good baseline. There are many nutrients that won’t be mentioned on a hay analysis that are still important aspects of a balanced equine diet. That’s a story for another day though!

Analysis is affordable so it’s well worth it. You will get a lot of information about what nutrients are present and what might be missing, particularly when it comes to macro and micro minerals. There are options for getting microminerals tested at some laboratories. Ensure that you ask for an equine analysis so that you get the information needed to assess the hay specifically for horses. Horses are hind gut fermenters and have different nutritional requirements from other livestock such as cows or sheep (ruminants).

Basic values for nutrients that you’ll want to look for in your hay include:

  • Moisture (in the “as received analysis” only)
  • DE (digestible energy)
  • ME (metabolizable energy)
  • CP (crude protein)
  • ADF (acid detergent fibre)
  • NDF (neutral detergent fibre)
  • ESC (ethanol soluble carbohydrate)
  • WSC (water soluble carbohydrate)
  • NSC (non-structural carbohydrate)
  • Calcium and Phosphorus
  • Other minerals may also be tested – I highly recommended doing this if you are going to be using the same supplier for a long period of time. There will be two columns present on your analysis, the “as received” column and the “dry matter” column. All ranges below appear in a dry matter basis (DMB) format except for the moisture.


Cured correctly, good hay should be about 10-16% moisture on an “as received” basis . This will ensure that the hay is not too dry or dusty and that it is digestible for your horse. Above 18% means that there could be mould present and above 25% indicates fermentation which is not only unhealthy for your horse but can also be a fire hazard in your barn. Avoid!

Digestible Energy (DE):

An average sized horse (1000 lbs) in light work needs around 20 Mcals per day. Mcals = per million calories. A good hay can range anywhere from 0.75-2 Mcals per pound of hay. You can use this evaluation to ensure you are giving your horse enough calories to meet his daily energy requirements.

Crude Protein (CP)

The level of crude protein (CP) in your hay is an important factor in how to balance your horse’s diet. Horses are, by nature, not adapted to eating a high protein diet so it’s important that you aren’t feeding too much. Legume hays, like alfalfa, are higher in protein than grass hays and they should be fed in moderation. The average horse needs roughly 12% protein.

Average crude protein in hay:

-Grass (eg. timothy, orchard grass, etc.) – can range from 8-14 % CP

-Mixed hay (often grass & alfalfa) – 14-17 %

-Legume hay – 15-20+ %

Acid Detergent Fibre (ADF)

The most undigestible parts of the hay, (eg. cellulose) are measured by the ADF. A low ADF value means that the nutrients in it are more digestible. A good range for ADF in hay is 35-45%. Anything above 45% is considered low in digestibility. “Digestibility” is a relative term when it comes to horses because they have the ability to use AFD fibre to generate a healthy gut microbiome that can also aid in the production of important nutrients within the hind gut of the horse. Just because they can’t completely break it down and obtain nutrients directly from it, does not mean that eating it is not beneficial to horses. High digestibility in hay could lead to excessive starch intake which is relevant with the rate at which horses are being diagnosed with equine metabolic syndrome (insulin resistance).

Neutral Detergent Fibre (NDF)

The NDF will show you exactly how much insoluble fibre is in your hay. It also will indicate how palatable the hay is. An NDF of 40-55% is an ideal range. Horses often will not eat hay with an NDF over 65%. The idea is, the higher the NDF, the less a horse will eat but this depends on the horse and the hay.

Calcium, Phosphorus and Trace Minerals

This is one thing that really gets people confused! Calcium (Ca) and phosphorus (P) are considered macro minerals which means they are required in higher amounts compared to other minerals in the diet. The calcium and phosphorus ratio is as important as the levels of calcium and phosphorus found individually in the diet. Adult horses need a range from 1:1 to 3:1 of Ca to P. An average adult horse, not in work, requires roughly 20 grams of calcium and 14 g of phosphorus per day. Growing horses require roughly 36-40 grams of calcium per day and 20-22 grams of phosphorus daily. So, if your hay is low in minerals, you will need to provide supplementation. Legume hays are higher in calcium and phosphorus than grass hays. It’s a plus to have the other required minerals in the hay tested as well to determine if supplementation might be needed. These include: potassium, magnesium, manganese, iron, copper, boron, sodium, sulphur, zinc, chloride and selenium. Common equine nutrient deficiencies include calcium, magnesium, zinc, copper, manganese and selenium.


Starch is often said to be a substantial source of energy for horses but horses are extremely sensitive to even low digestible (hydrolysable) starch levels in their diet. It is recommended that horses with PSSM and insulin resistance (IR) should be fed a forage diet that contains less than 15% starch but I would argue that this should be a rule for all horses since IR can result from feeding high starch hay. Additionally, the starch content is only part of the picture and needs to be considered in tandem with the amount of fibre that is present. Fibre is the most important glucose regulator in the equine diet. Hay can be grossly lacking in good fibre, leaving starch to influence blood glucose and insulin much more dramatically.

Ethanol Soluble Carbohydrate (ESC)

Some laboratories will list ESC as sugar – monosaccharides, disaccharides and oligosaccharides that are digested in the small intestine. For horses with metabolic disease or laminitis, the recommendation is to feed hay with an ESC of less than 10% but I would argue that this number should apply to all horses to prevent these diseases from occurring.

Water Soluble Carbohydrate (WSC) – AKA Hydrolysable Starch

This term pertains to sugars that can be dissolved in water including:




-some polysaccahrides

-fructans and pectins

Fructans are the most abundant water-soluble sugars in hay and your goal should be 10% or less to avoid sugar overload.

Non-Structural Carbohydrates (NSC)

This is the type of sugar most horses owners will be familiar at look at on a hay analysis. This number is significant in the management of sugar-related diseases and should be no greater than 10-12%. NSC needs to be considered, as mentioned previously, in relation to the fibre content in the diet. If the NSC is low but the fibre is also low, it indicates that the sugar will have more influence without the presence of fibre – which works as a blood glucose regulator. Low fibre hay should be avoided for all horses.

Nutritional Blood Testing

So, you’ve tested your hay. What’s next?

Identify the missing nutrients in your hay and ensure that your horse is getting those nutrients in another organic and species-appropriate form. Check out my article on common equine nutrient deficiencies for more help on this front.

I also recommend blood testing to give you individual information specifically from your horse starting with a basic mineral profile. From there, you can work with an equine nutritionist to establish if any other testing might be indicated after you receive the mineral profile. Consulting with a professional can also help you to resolve any mineral deficiencies your horse might be struggling with through test/wellness evaluations and diet planning.

Blood testing is a useful tool if you’re struggling to figure out why your horse isn’t feeling their best. It’s not always possible to know what your horse is absorbing/not absorbing and what dietary adjustments might be needed. You may be giving great hay and supplements but if the gut isn’t working optimally or they are having metabolic issues, your horse may not be absorbing/using nutrients correctly. Gut issues are a common and largely preventable problem in horses. Check out my equine ulcer article for more info on how to help heal your horses’ gut.

Have fun assessing your hay and happy feeding!


  1. The National Research Council – Nutritional Requirements for Horses 6th 2007
  2. The Merck Veterinary Manual: https://www.merckvetmanual.com/management-and-nutrition/nutrition-horses/nutritional-requirements-of-horses
  3. University of Minnesota Extension – Horse Management: https://extension.umn.edu/horse-nutrition/understanding-your-hay-analysis#calcium-%28ca%29-and-phosphorus-%28p%29-1320267