A safe diet strategy promotes weight loss without triggering metabolic, gastrointestinal, or behavioral problems. Using Henneke’s equine body condition scoring (BCS, a scale of 1-9), the goal is to reduce the horse’s body condition score by no more than one per month. An ideal score for most of our equine athletes is a 4 or 5—moderately thin to moderate, Shepherd said. Depending on the size and type of horse, a single score change could equate to a 25-50-pound weight loss over 30 days.
The key to healthy weight loss is a forage-based ration, explained Shepherd. Eliminating energy-dense grains and textured feeds is a simple way to cut excess calories and sugars (such as molasses) that overweight horses don’t need. A good-quality hay can provide enough fiber to satisfy hunger while also meeting an overweight performance horse’s energy requirements. Shepherd also recommends complementing the forage with highly fortified “balancer pellets.” These generally contain 30% crude protein and supply essential vitamins and minerals. Two key nutrients that must be met by either balancer pellets or a granular vitamin-mineral supplement are vitamin E, for horses without access to pasture, and selenium, for horses in deficient areas. The supplement or pellets should also include copper and zinc, which might be partially met by forage. Provide free access to salt near a fresh water source, as well.
Reaching a Target Weight
Using a weight tape, begin by recording the horse’s current weight and body condition score. Then determine his “target weight,” based on size, breed, and desired BCS. Shepherd said apps have been developed to help owners formulate breed- and performance-specific nutrition plans. She also suggests that the same person remain in charge of the weight tape, so the horse gets measured the same way each time. Monitor changes every two to four weeks.
A safe way to start a weight loss program is to feed 2% of the horse’s body weight on a “dry matter” basis per day. Shepherd used a 1,400-pound gelding with a body condition score of 7/9 doing “moderate” work (five hours of exercise a week, including some jumping) as an example. The rider’s goal is to lower this horse’s BCS to 5/9, a reduction of approximately 100 pounds. This gelding would require 28 pounds of dry matter (1400 x .02 = 28), which equates to 31 pounds of grass hay “as fed” if the forage is 90% dry matter (28/.9=31.1).
Feeding hay based on weight is a practical approach. The weight tape and body condition score will allow you to monitor progress and adjust the ration as needed. If the horse isn’t losing weight or reaches a plateau for a few weeks, Shepherd suggests reducing the amount fed by 10 to 20%. However, she cautions against dropping a horse’s forage intake below 1.5% of his body weight without first consulting an equine nutritionist. He might have metabolic or other issues to consider, and dropping forage too low can lead to colic and/or behavioral issues.
Of course, hay type and quality can affect how quickly a horse sheds pounds. But unless you have the forage analyzed, you can only approximate how much digestible energy, protein, fiber, vitamins, and minerals it supplies. A more mature, stemmier hay will be lower in calories and more filling than a less mature, soft, and leafy hay.
Horses that tend to be overweight are generally food-motivated, said Shepherd. So another important part of any dietary strategy should be slowing consumption. Using well-designed haynets or bags with smaller openings can prolong feeding periods and reduce boredom. Behavioral problems can develop in horses with too much time between feedings. Use grazing muzzles to restrict foraging in pastured horses, as turnout offers an added advantage in that horses burn calories as they move about. However, it’s important to make sure the grazing muzzle is well-designed, fits securely, and doesn’t interfere with the horse’s ability to drink. Shepherd also advised checking the muzzle periodically to make sure the holes haven’t become too big to limit grass intake.
In most cases, trimming fat from active horses is straightforward. Remember, they’ll gain an athletic advantage with a body condition score of 4 or 5, due to a higher power-to-weight ratio, said Shepherd. Once the horse reaches his target weight, based on body condition score rather than actual pounds, reevaluate and adjust the ration to ensure the horse is getting the nutrients he needs to thrive and compete.