The body of research on how to feed horses with metabolic problems is significant. However, understanding how to feed your metabolically normal animal might help prevent future metabolic problems. Indeed, it can be easy to forget about preventing metabolic problems, said Stephen Duren, PhD, founder of Performance Horse Nutrition, in Weiser, Idaho. He discussed how to keep your “normal” horse nutritionally sound during his presentation at the 2023 EquiSummit, a virtual equine nutrition conference held Sept. 5-6.

“We need to be concerned about keeping a normal horse normal because mistakes can be expensive,” Duren said. Mistakes in feeding young, growing horses can result in a lifetime of health and performance problems, which can be costly to treat and monitor.

“Finally, there are what I call the alphabet diseases—PPID, IR, EMS, PSSM,” said Duren. “These are all expensive to diagnose, medicate, and feed a special diet. Wouldn’t it be easier and less expensive to avoid feeding mistakes and keep the horse healthy from the beginning?”

Gastrointestinal Basics

To understand how to feed a horse, Duren said we need to first understand the digestive tract. He broke it down into the following three sections—the stomach, small intestine, and hindgut—noting that the large intestine (located in the hindgut), where the microbiome ferments fiber, is the largest.

“Anatomically, the digestive system is designed to rely on hay/pasture fermentation, yet many owners are concerned about what grain or concentrate or supplement they’re going to offer,” said Duren. However, he urged owners to consider the fiber content in the diet, because it is crucial to keeping horses metabolically normal.

Feeding Different Classes of Horses

Broodmares

When feeding broodmares, it is important to satisfy their nutrient requirements while maintaining a proper body condition score (BCS).

“The key to getting open/barren mares pregnant is to keep them at a Henneke BCS of 5-6 out of 9,” said Duren. “If they are too fat or thin, then mares take longer to begin cycling, have lower conception rates, and require more cycles to conceive.”

To do this, focus on offering hay/pasture at 1.5-2% body weight and adding a low-intake ration balancer to provide the essential nutrients, he added.

In early pregnancy, the fetus is very small relative to the mare and the foal’s birth weight.

“The mare’s nutrient requirements are very similar to maintenance,” said Duren. “Focus on hay/pasture, and give a balancer pellet. The biggest nutrition mistake is ‘feeding for two’ before it is necessary.”

In late pregnancy, however—the last 110 days of gestation—the fetus gains 80% of its birth weight. “This is when the mare has a large increase in nutrient requirements,” said Duren. “Because their intake capacity is limited due to fetal size, we need to replace some of the bulky fiber with concentrates. Decrease the forage to 1.5%, add in alfalfa for extra calories and protein, as well as a grain concentrate formulated for pregnant mares.”

The lactation period has the highest nutrient requirements. Duren suggests offering lactating mares a very high-quality hay with a fortified grain designed for lactation to avoid weight loss.

Growing Horses

Growing horses are our future athletic horses. If we make nutrition mistakes during this period, such as not providing the proper nutrients for successfully building skeletal tissue, they can have life–long implications.

“We need to provide the protein, minerals, and vitamins to support a sound skeleton,” said Duren.

Performance Horses

Performance horses are certainly not normal, said Duren. “It’s abnormal to keep horses in stalls, feed them meals, ride them, and trailer them, so it’s important to keep the diet and feeding behaviors as normal as possible, mimicking what would happen in a grazing situation.”

Offer high-quality forage to limit the amount of grain or concentrate needed, and when feeding concentrates to provide energy, protein, vitamins, and minerals, do not overfeed. “You want to feed the smallest amount of concentrate that will satisfy nutrient requirements while maintaining an appropriate BCS,” Duren said.

One of the biggest mistakes Duren sees is owners underfeeding performance feeds.

“Owners may not give their horse the full recommended meal because they feel the horse doesn’t need a large volume,” said Duren. “But feeding less than the full recommended meal means they’re not receiving all their nutrients.” He advises feeding a ration balancer to reduce the quantity your horse eats while still meeting his nutritional needs.

Take-Home Message

“Feeding mistakes are costly to the health of your horse as well as the time and money it takes to treat sick horses,” said Duren. “To keep a normal horse normal, maximize forage, only use necessary concentrates, and follow the label instructions.”