Spring Calories Count for Horses

Rapidly growing spring and summer pasture grasses are high in calories and sugar, which can contribute to weight gain in horses.

Photo: iStock

Your horse came out of winter in good body condition; how can you keep that trend going as the grass greens?

 

Ever had a horse that stays in good flesh or becomes just slightly lean during a harsh winter, but then promptly expands as soon as warm weather hits? Seemingly overnight, just as the pastures turn green, this horse appears as if it could foal at any moment. 

Although this might (or might not) be an exaggeration, rapid spring weight gain is not uncommon. In my experience, I have had two Thoroughbreds—usually a notoriously hard-keeping breed—that could maintain and gain weight on good-quality pasture and hay alone. 

“With cool-season grasses at peak production in the spring and warm-season grasses at peak production in the summer, there is an increase in overall forage availability from pastures, leading to the potential for weight gain,” says Bridgett McIntosh, PhD, Extension equine specialist in Virginia Tech’s Department of Animal and Poultry Sciences, in Blacksburg. “Rapidly growing pasture grasses in the spring and summer months are also higher in digestible energy (calories) and sugars, which contribute significantly to weight gain.”

Some of the best skills a horse owner can hone are estimating weight and body condition score. As owners who see our horses say in and day out, we are often incapable of assessing our charges objectively. Both of these calculations can provide a black-and-white way to evaluate weight changes and help you develop a management plan to either maintain your horse’s weight or change it.

How Much Does My Horse Weigh?

You can calculate a horse’s weight in a variety of ways. The most accurate is to use a scale designed for horses. Because most farms do not have such a scale—whether it’s because managers don’t perceive it as a need, don’t want to make the investment, or there aren’t enough horses on the farm to justify the cost ($600-1,000)—you might have to go elsewhere to find one. Our university’s feed company brings a scale to the farm and weighs all our horses once a month as part of their services. It never hurts to ask your feed dealer if this is an option, but keep in mind that a smaller company might not be able to provide such a service, especially for only a few horses. 

Another option for estimating weight is to use a weight tape designed for horses. Many feed companies provide these to clients for free, or you can purchase them from your local horse supply store or online. These tapes give you a relative idea of changes in the horse’s weight but not absolute values. 

Here at Midway University, students weight-tape the horses monthly after first weighing them on a scale. If the horse weighs more or less one month, both the tape and the scale will reflect this, but the numbers won’t be identical. Using the same tape every time, however, does improve the reliability of determining whether the horse gained or lost weight and approximately how much. Some weight tapes also “max out” at around 1,300 pounds, making them useless for assessing many Warmblood and draft types. Lara Levine, equine feed sales and technical representative for Southern States Cooperative, in Lexington, Kentucky, recommends using a weight tape every 30 days to monitor body changes. 

If you don’t have a weight tape, you can estimate your horse’s weight using a formula. With a long tape measure, determine your horse’s body length and heart girth, and plug those numbers into this formula to get an estimate in pounds:

(heart girth x heart girth x body length) / 330

Make sure you measure body length from the point of shoulder (and not from the center of the chest as you would to determine blanket size) to the point of buttock. You can use online tools (TheHorse.com/31852) or download apps to your smartphone that will do the calculations for you. 

What is Body Condition, and Why is it Important?

Body condition scoring (BCS, TheHorse.com/30355) is a relatively simple method of assessing fat cover on your horse. The nine-point scale is designed to describe the amount of fat and muscle a horse is carrying. A score of 1 is considered to be a poor or emaciated horse with no body fat, while a 9 is extremely fat or obese. 

For the everyday horse owner, BCS is a great way to determine if a horse is carrying more weight than desired. Assess a horse’s body condition at the same time that you weigh him, and record changes from one month to the next. Most horses need to stay between a 4 and a 6 on the scale. McIntosh also recommends calculating a horse’s “cresty neck score,” which Virginia Tech researchers developed.

“Generally you should be able to gently press into his barrel and feel the ribs but not see them,” says Levine of good body condition. “Watch out for a cresty neck and fat deposits along the back, around the tailhead, in the stifle area, and behind the girth; these indicate a horse that may be susceptible to developing the hoof disease laminitis (the separation or failure of the laminae that connect the hoof wall to the coffin bone within) or a metabolic issue such as insulin resistance (a reduction in insulin sensitivity that makes it more difficult for cells to take up blood sugar for metabolism or storage).”

Weight in combination with body condition score—especially when horses begin to acquire fat deposits—can alert an owner that a horse needs to shed some pounds.  

The Importance of a Veterinary Evaluation 

If we have a horse at Midway University that seems to keep or gain weight without excess forage or commercial rations, we have our veterinarian perform a thorough veterinary exam to rule out disease, as easy keepers are also more prone to developing health problems such as laminitis. 

“Typically, horses that regularly gain weight in the spring, summer, and sometimes throughout the fall are ingesting more calories and sugars from grass in the pasture,” says Levine. “Grass that is in the growing stage produces more sugar, so horses that are susceptible to these sugars tend to gain weight and be at risk for obesity and laminitis during spring and summer (especially following a rain when it’s been dry) and potentially again in fall when cool-season grasses hit another growing stage. Horses that have developed insulin resistance or (another) metabolic disorder, ponies, Warmbloods, and other easy-keeper breeds may be more prone to weight gain in the spring. Feeding too much of a commercial ration or offering high-quality hay during this time may exacerbate the problem.”

Limiting Feed Intake

Now that we know how to assess weight and body condition and have ruled out diseases or disorders, how do we prevent that spring weight gain? Horses left on their own will graze between 16 and 20 hours a day. 

“Grazing management strategies should include the use of muzzles, and drylots are recommended to reduce forage intake when pastures exceed the horse’s nutrient and energy requirements,” says McIntosh, as can happen when you’re growing good-quality pasture.

Limiting a horse’s time on and access to pasture is not always easy, depending on the horse’s management program. Herd dynamics might also come into play, especially if the group has some horses that are easy keepers and others that are hard keepers. Often when the hard keepers continue to graze, the easy keepers, being social, will also continue to graze even after they’ve met their nutritional needs. 

Some farms house easy keepers in stalls for several hours a day or put them on a dirt paddock. In both cases horses still need access to water, good-quality hay, and salt/minerals. Both McIntosh and Levine recommend restricting calories in the diet and increasing exercise to maintain and/or lose excess weight. 

Grazing muzzles can help decrease pasture intake for those air ferns out there.

Photo: Kevin Thompson/The Horse

Feeding a low-quality hay to meet forage needs with less calories might be necessary, says Levine. It is also important to stop feeding high-calorie commercial ration to horses prone to putting on weight in the spring. Easy keepers do not need the excess calories. Limiting pasture access also requires having someone move the horse on and off pasture, which can become time-consuming. 

Another option is to put a grazing muzzle on your horse. Some muzzles are a combination of halter and muzzle, while others attach directly to the horse’s halter. These can be an effective way to decrease pasture intake. Muzzles decrease pasture intake by 30-79%, depending on the type and height of the pasture (Glunk et al., 2014; Longland et al.). Monitoring grazing habits as well as body weight and condition will help you determine if the muzzle is effective. I have seen horses wear out the base of these muzzles, effectively increasing the size of the hole so they can consume more grass. So, if you choose to use a muzzle, make sure it is doing the job you expect it to do. 

Horse owners might also want to evaluate the forages in their pastures. Pastures that have more legumes, such as clovers and alfalfa, will tend to be higher in energy than pastures with more grasses. Local Extension specialists can help you evaluate your pasture quality and forage content. Pastures also tend to be higher in energy than hay, so giving a horse grass hay before turnout might help him feel “full” and not consume as much pasture. Another way to limit pasture intake is with rotational grazing. Use temporary fencing, such as electric tape fence, to limit how much of the pasture is available. As the horse grazes an area down, you can move the fence. As with stall and drylot confinement, make sure the horse with limited pasture space still has free-choice access to water and salt.

Nutrient Supplementation 

When you limit a horse’s feed intake, make sure he’s still receiving his required vitamins and minerals. “Feeds and supplements should be selected based on the nutrient content of the pasture and hay as determined by a forage analysis,” says McIntosh. “Little to no additional feed or supplementation may be required (for) some horses, depending on their exercise level and forage quality. For many horses, especially easy keepers, a ration balancer (also called a balancer pellet) is recommended to complement the forage to meet nutrient requirements without adding additional unnecessary calories.” 

Many feed companies have such a product that serves as a multivitamin. These are designed to be fed in small amounts, but contain the necessary protein, vitamins, and minerals to meet the horse’s nutritional needs without adding the calories he would get from a traditional feed.

Take-Home Message

In summary, owners should manage their horses to prevent or limit weight gain when pastures grow rapidly and increase in nutrient content during the spring and summer months. Evaluating weight and body condition regularly will help you detect gain as it’s happening. After ruling out medical conditions, you know it’s an issue that you can prevent or manage. The method you choose depends on your management style, pasture layout, and available time.

About the Author

Janice L. Holland, PhD, PAS

Janice L. Holland, PhD, PAS is an associate professor of Equine Studies at Midway College in Midway, KY. Her main academic interests are equine nutrition, pasture management, and behavior.

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