What is “Quality Hay”?

Written by Lynda M. Vanden Elzen

IMG_9370Nearly every day, someone asks us, “What is quality hay?”  Is 2nd cut better than 1st cut?  Is timothy better than orchard grass?  Are alfalfa mixes better than grass hay?  Is soft hay better than coarse hay?  Is low sugar hay better than “regular” hay?  These are all good questions.  The answer is that it depends on the horse you’re feeding.

Many horse owners who come here to look at hay want pretty, dark green, soft second cut, and then when we ask them about their horse, they tell us they have an overweight, sedentary quarter horse.  The hay analysis notwithstanding, soft hay is usually lower in fibre, which means the horse can eat more of it more quickly.  This is great for a hard keeping thoroughbred, but not so great for a fat pony.  A hay that is dark green in colour can be high in protein and nutrients, but it can also be high in nitrates, especially when you’re talking about our local hay here in the Fraser Valley.  High nitrates can tend to cause diarrhea in many horses.  So, from this short introduction, I think you can see that an appraisal of hay quality is relative to the horse who will be eating it.

A short checklist for evaluating the quality of hay relative to the horse who will be eating it:

Cut, Texture & Stage of Maturity

First cuts tend to grow for a longer period of time, so the plants are more mature – thus more stalky – at the time they are cut and baled.  Second cuts contain less mature plants, so tend to be softer.  As well, alfalfa tends to come up stronger in second and subsequent cuts, as it prefers dry soils and hot weather.

From Ashley Griffin, M.Sc, at the University of Kentucky:

“Nutrient value largely depends on the age at which the hay was harvested. Early maturity hay is very leafy and has a high nutrient density and palatability. Late maturity hay contains coarse, thick stems and fewer leaves than early maturity hay. Hay type should be matched to the horse type. Early maturity hay would be perfect for growing horses and lactating mares, but it may not be the best choice for horses with low nutrient requirements. Mid- to late-maturity hays are best for horses with low nutrient requirements, because the horses can eat more to satisfy their appetites without overeating and becoming fat.”

Species of Grass and/or Legume

Timothy and other grass hays tend to be lower in energy and protein and higher in sugars than alfalfa and other legumes, but the only way to know the nutrient value of hay is to test it.  Please check out our detailed articles on “Alfalfa and Protein” and “Timothy and Sugars“.

How Does it Test?

Hay testing can provide a great deal information about exactly what your horse is eating.  Gone are the days when we had to rely on how hay looked or what was in it – now we can tell, within about a 2% variance, how much protein, fibre, and energy it has, the carbohydrate and moisture levels, and with certain kinds of testing we can know mineral content as well.  Test results are often surprising, so we have learned above all that we just cannot assume how any hay will test.  Grass hays tend to test higher in sugars and lower in protein than legume hays like alfalfa, and alfalfa tends to have a much higher mineral content due to the fact that the roots of the alfalfa plant extend much deeper into the soil than those of grass species.  Alfalfa hays also tend to contain more energy per bite than grass hays (visible on the test as Digestible Energy or Relative Feed Value). The amount of fiber (ADF, NDF, Lingin) is important to consider as well, as it affects the amount of total feed the horse is able to consume in a given period.


Most people want dark green hay.  Many of the sources we consulted to prepare this article state that higher quality hay tends to be dark green.  This is true, but it is only part of the whole truth.  A dark green colour can indicate higher protein and nutrient levels, but it can also indicate high nitrate levels.  From the Kansas State University Research Extension:

“The potential for high nitrate concentrations occurs when crops such as corn, sorghum, cereal grains and some grasses are exposed to drought, hail, frost, cloudy weather, or soil fertility imbalance. Nitrates accumulate in the lower portion of the plant when stresses reduce the crop yield to less than that expected based on the supplied nitrogen fertility level. When fed to livestock, nitrates interfere with the ability of the blood to carry oxygen…Nitrate toxicity is a misnomer because nitrite (NO2 ), not nitrate (NO3 ), is poisonous to animals. After a plant is eaten, rumen bacteria rapidly reduce nitrates in the forage to nitrites. Normally, the nitrites are converted to ammonia and used by rumen microorganisms as a nitrogen source. However, if nitrite intake is faster than its breakdown to ammonia, nitrites will begin to accumulate in the rumen. Nitrite is rapidly absorbed into the blood system where it converts hemoglobin to methemoglobin. Red blood cells containing methemoglobin cannot transport oxygen and the animal dies from asphyxiation.”

Nitrates accumulate in a plant when the plant continues to take them up from the soil, but is unable to use them.  Factors influencing nitrate accumulation include anything that may stress the plant and stop it from converting the nitrates it has absorbed into amino acids (protein), or over-fertilization.  Some examples of plant stressors are drought, lack of sunlight, inclement weather, and cold temperatures.  Plants store their nitrates in their lower portions, so the height of the cutter blade when cutting hay can impact nitrate levels as well.  Higher nitrates can tend to cause diarrhea in horses, and we see this often in our local Fraser Valley hay especially.

Was the Hay Treated with a Drying Agent?

Another factor that can influence hay colour is moisture content at bailing.  Higher moisture hays will tend to be darker green, where lower moisture hays were usually left out in the sun longer to dry so will be more bleached.  This is why hays which were treated with propionic acid, a drying agent, will tend to be darker green and also tend to be less prone to dust or mold – because propionic acid application allows hays to be baled at 18-20% moisture as opposed to 10% or less in non-treated hay.  However, propionic acid has its own set of risks and drawbacks.  Dr. Juliet Getty hypothesizes:

“Not considered to be harmful, propionate is one of three volatile fatty acids (VFA) naturally produced by the hindgut bacteria during hay fermentation. The other two VFAs are acetate and butyrate. These VFAs are a significant energy source for your horse. Acetate is utilized by many tissues including the heart, muscles, and the brain. Butyrate provides energy for the cells that line the hindgut epithelium. Propionate is a major precursor toward glucose production through a process known as gluconeogenesis. And that’s a problem for the IR horse. Once propionate is absorbed and metabolized, it is converted to glucose! So when you feed alfalfa that has been treated with propionic acid, you are essentially increasing your horse’s blood glucose level, just as you would if you had fed a hay with a large amount of sugar and starch. Increased glucose leads to increased insulin. And the rest is… well, you get the picture.”

In our anecdotal experience here, we have also noted that some customers who have been feeding treated hay from other suppliers have had trouble with hard manure and loss of appetite in their horses.  This may or may not be due to having consumed treated hay, however it is worth noting.

Are Dust, Mold or Foreign Material Present?

Consuming excessively dusty and moldy hay can inflame the respiratory tract and cause heaves.  Molds in hay can also cause colic and produce mycotoxins.  That said, all hay contains some dust and mold.  Hay is grown outdoors in hay fields and there is just no way to ensure that any hay is free of dust or mold. Mold spore levels can be judged as follows, according to Pennsylvania State University:

 Feeding Risksa at Various Mold Spore Counts
a Risks refer primarily to effect of mold per se without regard to possible mycotoxin content. Dust may also reduce feed consumption.

Data from Richard S. Adams, Kenneth B. Kephart, Virginia A. Ishler, Lawrence J. Hutchinson, and Gregory W. Roth. 1993. Mold and mycotoxin problems in livestock feeding. The Pennsylvania State University.

Mold Spore count per gram Feeding Risk and Cautions
Under 500,000 Relatively low Risk
½ to 1 million Relatively Safe
1 to 2 million Feed with Caution
2 to 3 million Closely observe animals and performance
3 to 5 million Dilute with other feeds
Over 5 million Discontinue feeding

All hay should be inspected prior to feeding to check for mold, dust, and foreign materials such as weeds and anything else that may have been captured inadvertently at bailing.  We have seen some pretty interesting things show up in hay bales – from sticks and mud, to a dead coyote!  Farmers hay hundreds of acres at once in many cases so these things happen!  That said, most of the time, if a horse is being fed enough, he won’t try to eat moldy hay, weeds, or foreign materials.

In Conclusion

The definition of “quality hay” depends on the horse who will be eating it.  There are some absolutes that are true across the board, as above, such as mold and nitrate content, but in terms of protein, texture and fibre, trace mineral content, carbohydrates/sugars, and energy content, there is no answer that is true across the board, because every horse is an individual.

Many of our horses these days are overweight and sedentary, and many of those are metabolically thrifty as it is, thus many of them can benefit from a higher fibre, lower sugar, moderate to lower protein, lower digestability hay.  It keeps them eating longer between feedings and reduces the total amount of calories they can consume in a given time period.  In contrast, a harder keeping, harder working horse like a racing thoroughbred or an event horse requires as many calories per bite as we can get into them, so a softer, higher protein, higher energy, lower fibre hay is better for them.  Your horse is an individual, so the definition of what is a quality feed for your horse is as unique as he is.



“What You Need To Know About Horse Hay”  – Dr. Dennis Cash Ph.D, Montana State University, Ashley Griffin M.Sc, University of Kentucky, Jennifer Nadeau Ph.D, University of Connecticut, Dr. Christine Skelly Ph.D, Michigan State University (http://www.myhorseuniversity.com/resources/eTips/September2011/Didyouknow)

“Selecting Horse Hay” – Ashley Griffin M.Sc, University of Kentucky (http://articles.extension.org/pages/11223/selecting-horse-hay)

“Forage Facts Publication Series – Nitrate Toxicity” – Kansas State University Research and Extension (https://www.asi.k-state.edu/doc/forage/fora13.pdf)

“Quality Hay Production” – Cooperative Extension Service, University of Kentucky College of Agriculture (http://www2.ca.uky.edu/agcomm/pubs/agr/agr62/agr62.pdf)

“Hay Judging” – Oklahoma Cooperative Extension Service PSS-2588 (http://www.okrangelandswest.okstate.edu/files/grazing%20management%20pdfs/F-2588web.pdf)

“Do not feed moldy hay to horses” – University of Minnesota Extension (http://www.extension.umn.edu/agriculture/horse/nutrition/moldy-hay/)

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