Question

Could the protein in a balancer pellet cause my yearling filly to be flighty and oversensitive? I am specifically worried about soy consumption.

Answer

Soybean meal is a high-quality source of protein for horses because of its excellent amino acid profile. In fact, soybean meal is often considered the gold standard when it comes to plant-based protein sources for horse feeds, particularly those intended for young horses. Many well-formulated feeds and supplements contain soybean meal, including several brands of balancer pellets.

Regarding the filly’s excitability, it is unlikely that soybean meal consumption, particularly the amount that would be included in a ration balancer, would result in a behavioral change. This is not to say, though, that behavior is not influenced by feeding management. Changes in behavior are commonly observed in horses when the energy fraction of their diet is increased, especially when that increase is achieved quickly and not gradually over several days. Extensive research has shown that consumption of nonstructural carbohydrates (NSC) may affect behavior in susceptible horses. But, as you might suspect, many horses are not affected at all by NSC in the diet.

Other factors that may contribute to your filly’s increased excitability include the weather (especially a shift to cooler temperatures), exercise and turnout frequency and duration, and other dietary factors, such as hay source. If she is being fed a high-energy hay like alfalfa, switching to a lower energy hay such as a mixed-grass hay may help moderate her energy level. A thorough diet evaluation that consideres everything your filly consumes in a day will ensure adequate intake of all nutrients.

Consistency in handling young horses, including establishing behavioral boundaries, is also crucial. A well-mannered young horse is not only a joy for its regular handlers but also for the people it will encounter during its lifetime, such as farriers, veterinarians, and other professionals.