Glycemic Response to Soaked Hay

Horse HayFor horses diagnosed with Equine Metabolic Syndrome, obesity, laminitis and/or insulin resistance, the need for dietary management of nonstructural carbohydrate intake is necessary. One management tool horse owners can use is regulating the glycemic response in diseased horses, which is the effect food has on blood glucose levels after a meal. Past research has shown that soaking hay for 30 to 60 minutes reduces nonstructural carbohydrate levels; however, researchers have yet to explore if hay soaking has an effect on glycemic response. Recently, researchers at Middle Tennessee State University examined how soaked hay versus non‐soaked hay affected the glycemic response in horses.

Two different hay types were evaluated both as soaked hay and non-soaked hay; prairie grass and alfalfa. Wet hays were soaked in cold water for 60 minutes and 12 healthy horses (average of 17 years and 1,207 pounds) were fed the hays. Blood samples were taken immediately at the time of feeding and every 30 minutes for 2 hours, and every 60 minutes up to 5 hours.

Researchers found that horses had a higher glycemic response to alfalfa hay compared to prairie grass hay. However, there was no difference in the glycemic response to non‐soaked or soaked hay of either type. Over time, plasma glucose levels were higher in horses fed alfalfa versus grass hay.

Researchers concluded that although the type of hay fed influenced the glycemic response, no difference in physiological glycemic response was observed in healthy horses fed non-soaked or soaked hay. Additional research is needed to determine if soaking hay has physiological merit in horses diagnosed with Equine Metabolic Syndrome, obesity, laminitis and/or insulin resistance.

For more information on this study, click here.

For more information on hay soaking, click here.

Summarized by: Devan Catalano, BS, University of Minnesota.

This article is reprinted with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at

Prevention and Management of EMS in Horses

There is no treatment or cure for Equine Metabolic Syndrome (EMS), so taking preventative measures though diet and exercise are the best defenses against the development of EMS.

Crinkles on Toby's neck are evidence of his 'overweight' status

Here are some great defensive strategies to help prevent your horse from developing EMS:

    • Prevent obesity by providing a forage-based nutritionally balanced diet with controlled starches and sugars.
    • Maintain an optimal body condition through regular exercise.
    • Work with an equine nutritionist or veterinarian to understand what a healthy weight and body condition is for your horse to help prevent over-feeding or dietary imbalances that can contribute to EMS.

For horses who already are dealing with EMS, follow these tips to help successfully manage their condition:

    • Prevent or reduce obesity through controlled starch and sugar in the total diet along with exercise (unless horse is painful from laminitis episodes).
    • It is recommended that these horses have very little to no access to fresh pasture to avoid the overexposure to the sugars in grass.  Use of grazing muzzles or a dry lot are good alternatives to stall confinement, as this allows the horse to exercise on its own.
    • Have a nutrient analysis done on your hay to understand the NSC content – keeping in mind that it is important to understanding to NSC content of the total diet (hay + grain, if applicable).
    • Soaking hay (15 – 30 min warm water) can help leach out some of the sugars in the hay, just be sure to feed the hay right away before it spoils, and discard the sugar waste water, so the horse does not have access to it.
    • Low calorie ration balancers are good horse feed options to balance the diet if there are vitamin and mineral deficiencies from feeding a forage only diet, and/or from soaking hay.



What is Equine Metabolic Syndrome (EMS)?

EMS is a hormonal disorder in horses, similar to metabolic syndrome in humans, that is characterized by obesity, insulin resistance, and abnormal fat deposits, which can predispose affected horses to chronic laminitis.

What types of horses are affected?

First and foremost, most horses do not suffer from EMS.  The majority of horses tolerate dietary carbohydrates such as starch, sugar and fructan, quite well, and thrive on this important and readily available source of energy. Performance horses in particular need sufficient non-structural carbohydrates (NSC) in their diets for work and recovery after exercise. Too little starch and sugar in the diet can diminish athletic performance over time horse grazing and looking back representing What is Equine Metabolic Syndrome (EMS)?in non-EMS horses.

EMS can occur in any breed, however ponies, Morgans, Paso Finos, and horses that tend to be “easy keepers” seem to be most vulnerable to developing EMS. It should also be noted that not all obese (fat) horses are insulin resistant, and not all insulin resistant horses are fat.

How do I know if my horse is insulin resistant (IR)?

Veterinary diagnostic testing (blood work) is recommended to confirm IR, but here are some other classic signs of insulin resistance in horses and ponies:

    • A classic sign of IR is a “cresty neck”, of which a clear correlation between neck circumference and IR has been documented.
    • Horses with regional deposits of lumpy or dimpled fat pads behind the shoulder, around tailhead, and/or over the loin are suspect of being IR.
    • Horses that seem to gain weight rapidly, or blow up easily, particularly in spring with new pasture growth, relative to other horses may indicate IR.
    • Horses that are tender footed, and/or that demonstrate rings on the hoof wall, expanded white line and blood spots on the soles of their feet, suggests mild, chronic bouts of laminitis and IR.

EMS is sometimes confused with other clinical disease such as Cushing’s Disease and hypothyroidism due to similar clinical signs, despite different underlying causes. It is very important to work with a trusted vet to ensure an accurate diagnosis if any of these conditions are suspected.

Traditional Grain or Ration Balancer?

When it comes to feeding a horse with EMS, it’s important to pay close attention to their starch and sugar intake.

Since forage should always be the base of any good equine diet, it’s important to know your hay’s NSC content. This can be done by a commercial laboratory via your local feed representative. Contact Nutrena to inquire about hay testing in your area. Depending on the findings, you can adjust the amount being fed and possibly soak the hay to remove some of the excess sugar.

If you are feeding a traditional grain, it is best to look for one especially formulated for horses with metabolic issues such as Safe Choice Special Care. (link to product)

However, if you are concerned about caloric intake, a ration balancer might be a better option. This is a concentrated feed that is designed to be fed in smaller amounts, reducing caloric intake. A product like Empower Topline Balance provides amino acids, organic trace minerals, vitamins, pre- and probiotics in a concentrated form, designed to balance and complement the nutrition coming from forage.

While both products are low in non-structural carbohydrates (NSC), the major difference in the two products is the caloric content. Safe Choice Special Care is higher in calories compared to Empower Topline Balance. Because Empower is concentrated, the feeding rate (pounds per day) is much lower compared to Safe Choice Special Care. For horses needing additional calories beyond their forage, while keeping the diet balanced, Safe Choice Special Care would be a great choice. For horses that are overweight or doing just fine with forage only but would benefit from balancing the total diet with regard to amino acids, vitamins, minerals, a ration balancer such as Empower Topline Balance would be a good fit.

Estimating the horse’s target body weight and doing a body condition score are great tools to help determine which feed is best for your horse as well as how much to feed them based on manufacturer recommendations.

Ready to ensure your horse is getting the optimum nutrition at feeding time, every time? Find the perfect feed formulated specifically for horse’s needs with our Feed Selector Tool.

Feed Selector tool

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