Understanding Hay Analysis

November 30, 2020

In my recent article on the benefits of turnout for horses, I talked about the importance of grass turnout. In North America, we have seasonal ebbs and flows and it’s not always safe to turn your horse out. So, the next best thing? Quality hay! It’s important that you know how to tell the difference between good quality hay and something that might not give your horse the nutrition they need. Poor quality hay can cause nutritional deficiencies, gut issues and other serious health problems. Let’s talk about how to assess your hay quality. 

When your horse can’t have the perfect scenario (rotational grass turnout on well-managed pasture), 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, low stamina and other serious illnesses. 

So how can you tell if your hay is making the cut? Hay quality can vary greatly depending on the region it is grown in, species of grasses, stage of grass maturity, fertilization methods, 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 want to ask you hay supplier about the types of grasses included in your 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 or herbicides used. 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 sprays and, whenever possible, choose hay that has been fertilized with organic fertilizers such as manure and compost. 

Judging Hay With Your Senses 

Taking a good physical look at your potential 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 as well as the outside of the bale. Here are the main traits to look for in your hay: 


Green color indicates 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 indicates high quality, digestibility, and that it has been harvested at the optimal time (not as a mature/flowering plant). This is a much more nutritious option than mature grasses.  Course stems, seeds or flowers means the hay was harvested in its mature stage, is less nutritious and less digestible. Flowers will only be seen in mature legume hay. Seeds may be seen in mature grass hay. 

Picture: Flowering alfalfa (legume).  

Weeds and foreign material means the hay was poorly managed when grown. Weeds 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. Blister beetles are toxic and can infest mature alfalfa hay so do be sure to look for these. (see picture below). 


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

Understanding Basic Hay Analysis 

Getting your hay analyzed is an important part of getting to know your hay. 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 the pieces of the equine nutrition puzzle but they give you 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! 

Hay analyses average about $20.00 per test so it’s well worth it. A good hay supplier will often have this testing done and you can simply ask them to send you the results. You will get a lot of information about what nutrients are present and what might be missing. If you are doing he testing yourself, 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).   

Some basic values for nutrients that you should 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), Calcium and Phosphorus. Other minerals may also be tested which is a plus. 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. 

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 

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 and average of 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. 

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 ideal. 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 or other foods that balance the calcium: phosphorus ratio. 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.

Assessing Your Horse’s Diet 

An important aspect of assessing your horse’s diet is to determine how your horse is doing on his current feeding schedule. His body condition, energy level, hoof health and even his mood can be affected by hay quality. Always consider your horse’s current state of health when determining the best course of action with his diet. If you’re not sure, ask your veterinarian or hire an equine nutritionist to help you. 

Nutrient Deficiency Hair Testing 

So, you’ve tested your hay, evaluated your horse’s overall diet (including supplementation) and you’re still having trouble with your horse’s health. What next? The next step is to hire an equine nutritionist to help you. Nutritional deficiencies can present like specific health problems in horses so it’s important to try and figure out if it’s simply that your horse isn’t getting enough of all the equine-required nutrients or if they have an underlying disease that needs further attention from your veterinarian. If your horse is really struggling clinically or has a diagnosed disease, they may require blood testing to check specific vitamin levels. Particularly useful blood tests include vitamin B12 and vitamin E. 

Along with hiring a nutritionist, you can also opt to do hair testing to determine your horse’s entire nutritional profile. Hair testing can give you individual information specifically from your horse including all the amino acids, fatty acids, minerals and vitamins that may need adjusting. This can be a very useful tool if you’re struggling to figure out why your horse isn’t feeling their best. It’s not always easy to get all the information about 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, your horse may not be absorbing nutrients correctly. Gut issues are a common and preventable problem in horses and I will discuss this further in future articles but probiotics along with other gut-supportive supplementation are often necessary. Check out my blog on equine ulcers to learn more about how to address gut disease in your horse. 

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