Feeding the weanling and yearling horse

Ideally, you should feed young horses to grow at a moderate, steady rate. The National Resource Council (NRC) recommends rates of average daily gain for horses. Recommended average daily gain values for horses of different mature bodyweights range from 0.28 to 0.39 percent and 0.15 to 0.21 percent of the horse's body weight for weanlings and yearlings, respectively. Feeding a young horse for a moderate growth rate doesn’t result in a smaller horse. 

Feeding a young horse for a maximum growth rate is undesirable because bone hardening lags greatly behind bone lengthening. At 12 months old the young horse could reach about 90 to 95 percent of its mature height but only about 75 percent of its mature bone mineral content.

Ideally, young horses should gain weight at a rate that their developing bones can easily support. Growing bones don’t have the strength to support rapid weight gain from overfeeding, especially energy. Rapid weight gain can also make other skeletal anomalies worse. In these cases the risk of developmental orthopedic disorders (DOD) and unsoundness increases.

DOD and unsoundness can also occur during uneven growth. For example, switching an underfed, slow growing horse to a good diet that allows quick growth, increases the risk of DOD. Foals between the ages of 3 and 9 months of age are at greatest risk of DOD.

Natural feedstuffs usually provide enough major minerals such as calcium (Ca) and phosphorus (P). Young, growing horses need a diet ratio of Ca to P between 1 to 1 and 3 to 1.

Changes in forage or grains in the diet will likely alter the Ca to P ratio.

• Legumes tend to have more Ca than P and are higher in Ca than grass.

• Grains are typically much higher in P than Ca.

Common feedstuffs usually don’t provide enough trace minerals. Thus, supplementation is usually recommended.

Always provide free choice salt. Horses will regulate their own salt intake.

You should also supplement vitamins to most young horses.

High quality forages provide young horses most of the energy and nutrients they need.

Weanling diets should never be less than 30 percent forage by weight. Ideally, they should have much more forage. Maximizing forage intake will mimic natural feeding behavior and bring about gut health.

You can test your hay to find its energy and nutrient content. Pasture energy and nutrient content is harder to account for because it changes. Thus, don’t rely on pasture alone to provide your young horse with all the nutrients they needs.

A horse’s ability to efficiently use forage develops over time. Thus, young, growing horses need more carbohydrates than mature horses. Often, horse owners feed more cereal grains (e.g. oats and corn) at the cost of forage when forages can’t provide enough energy. But there’s a limit to how much cereal grain you can feed a horse without harm. The grain ration should contain added fat.

You can formulate your own concentrate ration or purchase a commercially prepared concentrate formulated for horses at different growth stages. Only feed enough concentrates to achieve the desired growth rate and maintain a moderate body condition score. Don’t feed any more than this.

Feed the concentrate part of the diet across multiple feedings throughout the day. Remove and replace uneaten concentrate with fresh concentrate the next feeding. Always consider the expected feed intake when calculating your horse’s daily ration.