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Can Horses Eat More Hay Without Weight Gain? The Surprising Factors

Over the years I've had the pleasure of speaking to thousands of customers and listening to their concerns about obesity, gastric ulcers, boredom and consumption of manure, dirt and shavings for their meal fed horses (or donkeys, mules and grazing barnyard companions). They really want to feed more hay or transition to free-choice to satiate their herd, but they don't have the confidence to make the switch.

Feeding limited amounts of highly palatable/digestible energy hay perpetuates the vicious cycle of much anticipated meals, followed by periods of time without forage. And that's not the way horses were designed to eat. So, the gastric acid discomfort builds up, boredom begins and our horses become increasingly anxious - and sometimes aggressive - come meal time.

Read on to learn how a simple shift in your approach and forage selection can 1) reduce or eliminate meal time stress and 2) give your horse more chew time and bulk (without the weight gain).

Two bay horses eating hay
​Physically and mentally, all grazing animals are designed to forage, at will, throughout the day and night on a variety of forages with a vast array of fiber content. They also move from place to place while doing so. This innate grazing behavior:

Can My Horse Really Eat More or Free-Choice Without Gaining Weight?

​It depends on the hay you feed. If the hay is calorie dense and/or has an appealing taste and smell, your horse will likely be far more enthusiastic about eating it as fast as possible. Since most of my customers are considering slow feeding to manage or lose weight, we want to find hay our horses can chew on that's lower calorie and not as tasty or aromatic. The answer? Provide bland diet food to naturally slow consumption rate and encourage self-regulation!

​These principles also apply if:
  • Your horse is a healthy weight, but is currently fed measured meals and you want to feed more or offer a less appealing always have hay source.
  • Your herd has free choice forage available, but is gaining weight and you are considering feeding meals again.
  • Your horse is turned out on pasture part time (grazing muzzles are a must) and then confined/fed meals to manage his/her weight. Better understand the factors that contribute to sugar levels in pasture and hay.
  • You have been advised to put your horse on a "diet" without addressing the diet itself. 

Two Important Considerations for Successful Free Choice Feeding or Increasing Measured Meals

  1. Your Hay – Palatability, maturity, Nonstructural Carbohydrates (NSCs), digestible energy (DE) and nutrient/protein content of the forage being fed
  2. Your SupplementsMeeting vitamin/mineral requirements (in proper ratios) to ensure proper hormone/thyroid, immune and neurological function 

​The Palatability Factor & Sugar Content

Feeding a less palatable hay naturally slows consumption rate. This factor alone promotes self-regulation, which is the ability to stop eating despite the presence of forage.

While researching the topic, we discovered a study conducted by the founder of, Katy Watts. The study sought to better understand the contributing factors that determine the palatability of hay and whether sugar content (WSCs) influenced the horses' hay choice.

Watts tested six different types of hay being fed in Colorado at Equi-Analytical for a complete nutrient profile. All of the hays were of good hygienic quality, without mold or dust and had bright green color.

Her discoveries?
  • Aroma was the main contributing factor in the horses' preferences. They preferred hay that smelled most like fresh cut grass. 
  • Second to smell was texture/lower NDF fiber content. Softer hay was preferred.
  • The two hays ranking lowest in palatability had the highest fiber content (NDF) with no discernible aroma.
  • Sugar content (WSCs) did not influence the horses' preferences - hence the importance of testing hay despite palatability.​
Horse eating hay from trays in palatability of hay study conducted by Katy Watts of
Photo courtesy of Katy Watts, founder of

If you cannot test your hay for sugar content/nutrient levels, you can smell and feel the texture (maturity) by opening a bale. Coarser hay with no discernible aroma should be far less appealing. Mature grass hay (head without seed) or grass hay straw (mature grass hay with the seed head harvested) has the lowest propensity for storing sugar and starch (second to environmental conditions). To achieve adequate protein in the diet, you may need to supplement mature grass hay with limited amounts of an immature cutting of grass hay, alfalfa, or a protein rich concentrated supplement. Testing your hay is always optimumLearn How & Where to Test Your Horse's Hay & Interpret Results

The Donkey Sanctuary recommends free choice barley straw in addition to limited grass hay or pasture as a viable option to achieve satiation and gut fill for donkeys, mules and horses. ​

​What are Non-Structural Carbohydrates (NSC)?

NSC is a term describing the carbohydrate content of plants - defined as WSC% + Starch% or ESC% + Starch%, depending on the vet or nutritionist you are consulting. For individuals that are overweight or have Cushings Disease (PPID), Insulin Resistance (IR) or Polysaccharide Storage Myopathy (PSSM), the recommended NSC levels in the diet should be 10% or less.

According to Equi-Analytical’s common feed profile:

NSC (WSC% + Starch%) levels of grass hay in the normal range are 8.037% -17.663%

​What is NDF?

​Neutral Detergent Fiber (NDF) represents the fibrous bulk of the forage and is a main contributing factor to texture/palatability. It gives the plant rigidity, enabling it to support itself as it grows. NDF digestibility in forages is directly related to leaf-to-stem ratio. The NDF in leaves is significantly more digestible than NDF in stems. More mature cuttings possess a higher stem-to-leaf ratio, resulting in lower digestibility and palatability.

According to Equi-Analytical’s common feed profile:

NDF levels of grass hay in the normal range are 55.524% - 69.319%

Importance of Routine Dental Exams When Feeding High NDF/Mature Forage

Routine dental exams are a necessity for all of our beloved companions, regardless of what they eat. Higher NDF/ mature forage requires optimum mastication (grinding), which requires unobstructed motion of the jaw. Any condition causing pain can discourage the required chew time necessary for proper digestion. 

​The Digestible Energy (DE) Factor

Energy contributions from protein, fiber, nonstructural carbohydrates and fat form the foundation of the system. Gross Energy is the total energy value of a feed. Digestible Energy is Gross Energy minus the energy contained in the feces and measured in megaCalories (Mcal) per kilogram of feed (Mcal/kg). 

The lower the DE, the less calories assimilated per kilogram (2.2 pounds) of hay.

According to Equi-Analytical’s common feed profile:

Horse digestible energy levels (Mcal/lb) of grass hay in the normal range is 0.811 -1.008.​

5 ​Tips for Transitioning Successfully to Feeding More or Free- Choice Forage

​In addition to feeding less palatable, lower-sugar/higher NDF (mature)/lower DE hay, I've found over the years that the following tips have helped contribute to me and my customers' success.

1.  Implement Slow Feeders 

​Using slow feeders or bale nets minimizes wasted hay and promotes longer chew time, which further reduces the particle size and rate of consumption. Chewing activates saliva production providing moisture (higher saliva to forage ratio) and aids in digestion. This better prepares fiber content for optimal digestion as it travels through the remainder of the digestive tract. 

Slow feeding prevents individuals from picking through it to eat only the tastiest morsels (especially important with less palatable hay) and helps to regulate metabolism and insulin spikes. 

2. ​ Avoid Confinement 

​Mobility stimulates gut motility and mimics natural grazing behavior. It also lessens mental and physical stress. 

3. ​ Supplement for Balance

Every hay-only diet requires supplementation. No hay is ever balanced to itself (optimum ratios), nor will it contain the National Research Council (NRC) minimum requirements of all vitamins and minerals. It is important to note that NRC minimum requirements are levels that borderline deficiency - hence the term minimum. These levels may not necessarily be optimum. If you don’t test and balance your hay, feed a comprehensive concentrated vitamin/mineral supplement to promote optimum immune, hormone, neurological and thyroid function.

All hay only diets should also include a healthy source of omegas with optimum 3-6-9 ratios (ground flaxseed or chia). Omegas are rapidly destroyed during the curing process of hay. A study at the Equine Science Society determined that feeding a 1000 pound horse 4.5 ounces of flax seed resulted in blood levels of omega-3 comparable to horses on pasture.

4. ​ Feed Loose Salt to Avoid Dehydration & Provide Clean Water

​Correct sodium balance in the horse is necessary for proper thirst response and body water equilibrium (electrolytes and hydration). Salt is necessary for the production and secretion of bodily fluids such as sweat, saliva, intestinal tract fluids, urine and mucus. The vast majority of diets do not provide sufficient sodium without supplementation. This can greatly reduce the risk of impaction colic due to dehydration.

5. ​ Introduce New Forages Slowly

​Begin by blending small amounts of less palatable hay with your current forage, increasing the percentage over time. Blending palatable and less palatable varieties typically results in the same enthusiasm and rate of consumption.

When your herd has adapted to the new forage, feed the less palatable hay separately or exclusively to achieve optimum results. 

Concluding Remarks

  • To the best of my knowledge, the palatability concept in feeding free choice or increasing meal sizes is rarely explored or written about, but certainly worth considering. Always consult your veterinarian when making any changes in your feeding program.
  • Domestication of grazing animals designed to forage 24/7 on a variety of plants, brush and trees certainly presents challenges. In nature, their activities consist of walking and grazing, interacting with herd mates and periods of rest.
  • On the other hand: confinement, feeding limited amounts of palatable, highly digestible forage and isolation can cause obesity, anxiety-related stress, vices and boredom – especially when they suppress a horse's natural instincts.
  • Providing appropriate free choice forage, freedom of movement and a species appropriate environment will provide your herd with the basics of their natural lifestyle and instincts - despite domestication.

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Monique Warren, Hay Pillow Founder with the Hay Pillow Slow Feeder product line - standard ground hay pillow, mini hay pillow, hanging hay pillow & horse trailer manger hay pillow

About the Author

Monique Warren invented the Hay Pillow® slow feeder and is the owner of Hay Pillow Inc. ​Warren has been an equine guardian for over forty years and slow-feed advocate for over 10 years. She contributes equine nutrition, digestive and hoof health articles to publications such as Equine Wellness, The Journal, The Naturally Healthy Horse, Natural Horse Magazine, Nicker News, The Horse's Hoof and Miniature Horse World Magazine. Equine nutrition and horses feet are her passions. She resides in Southern California.

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