Horse owners receive nutrition advice from many sources, from well-meaning horse owners online to barn managers and trainers. While some feeding practices have been passed down through generations, not all align with modern equine nutrition research. Misconceptions about forage, grain, supplements, and feeding habits can lead to unbalanced equine diets or unnecessary health risks.

Prioritizing what horses truly need nutritionally helps owners make informed feeding decisions that support digestive health, body condition, and performance. Nicole Rambo, PhD, equine nutritionist at Kalmbach Feeds Inc., in Upper Sandusky, Ohio, separates fact from fiction by addressing several common equine nutrition myths still circulating in horse barns today.

Myth: A Forage-Only Diet is Enough for Horses

A forage-first diet supports digestive health, but pasture or hay does not always meet a horse’s nutrient needs, particularly for those in work. While some horses in light work can maintain body condition on forage alone, some need additional calories to support performance and body condition.

“Forage quality varies depending on plant species, stage of growth, and soil conditions,” says Rambo. “Because of this variability, forages may be deficient in certain nutrients, which is why many horses benefit from a grain concentrate or ration balancer to ensure balanced nutrition.”

Workload should also factor into diet decisions. “While vitamin or mineral deficiencies can be difficult to detect, energy deficiencies are often easier to identify, typically appearing as poor body condition or lack of energy,” Rambo says.

Myth: Supplements Can Fix a Poor Diet

Some owners might try to correct dietary issues by adding more supplements. However, manufacturers design supplements to complement a balanced feeding program, not replace one. Over-supplementation can also create nutrient imbalances and unnecessary expense.

Supplements cannot compensate for poor quality or insufficient forage or concentrate. “Feeding multiple, uncoordinated supplements can create dangerous imbalances or toxicities, particularly with fat-soluble vitamins and minerals like selenium,” says Rambo. “Targeted supplements can help in specific situations, such as supporting joint health in senior horses or digestion during stress or travel.”

Myth: Feed a Thin Horse More Concentrates

Simply increasing concentrates for a thin horse can raise the risk of metabolic problems, colic, or laminitis, says Rambo. The overall feeding program, including the type and quality of forage and concentrate, usually matters more than the amount of grain alone.

“First address issues such as dental problems, parasites, or ulcers that may be contributing to weight loss,” says Rambo. “Then focus on maximizing high-quality forage intake, such as pasture or alfalfa. Underweight horses should ideally have free-choice access to quality hay and consume at least 2% of their body weight in forage daily. Improving hay quality, such as feeding an alfalfa-grass mix, and choosing feeds higher in fiber and fat and lower in non–structural carbohydrates can also help.”

Myth: Performance Horses Need High-Starch Diets

Historically, trainers and horse owners fed many performance horses (especially racehorses) high-starch grains such as oats and corn to supply rapid energy. However, large starch meals can overwhelm the small intestine, says Rambo. When undigested starch reaches the hindgut, it disrupts microbial balance and can contribute to acidosis, gastric ulcers, and other digestive problems. “Modern research shows that horses do not require high-starch diets for performance,” says Rambo. Forage-focused diets with added fat and fiber can give performance horses enough energy while supporting gut health.

Myth: Feed Bran Mashes

For generations, horse owners have fed bran mashes as a warm winter treat or to encourage hydration and appetite after stressful events. While horses often find bran mash palatable, the traditional practice can also create nutritional concerns.

“A major concern with bran mash is its high phosphorus-to-calcium ratio,” says Rambo. “Historically, horses fed large amounts of wheat bran developed nutritional secondary hyperparathyroidism—often called ‘big head disease’—because the imbalance causes the body to pull calcium from the bones.” Bran mashes can also disrupt the microbes in the hindgut, which might increase the risk of digestive problems, colic, or in some cases, laminitis. “A better alternative is to add warm water to the horse’s regular feed to create a mash, rather than introducing a new feedstuff like bran.”

Take-Home Message

Long-standing feeding traditions do not always align with equine nutrition research. Starting with quality forage, then adding concentrates and targeted supplements when needed, can helps support digestive health, body condition, and performance while avoiding nutrient gaps.