The research team’s results indicate that a forage-only diet and transportation prior to exercise could positively impact horses’ performance. | Photo: Anne M. Eberhardt/The Horse

Researchers know that diet can impact a horse’s metabolism. Recent studies have also confirmed that diet alters horses’ metabolic responses to exercise, especially when comparing all-forage diets with more traditional high-concentrate diet. However, it hasn’t been clear how transportation—an important factor, considering that performance horses are transported to competition venues on a regular basis—impacts metabolism. But researchers recently learned it could have a more significant impact than previously thought.

Study Design

Researchers from the Wågen National Center for Education in Trotting and the Swedish University of Agricultural Sciences, both in Sweden, separated six trained adult Standardbred trotting mares into groups, in which they consumed one of two diets with similar calorie contents. One group consumed forage only (Group F, a timothy and meadow fescue haylage) and the other ate a 50/50 mix of the same forage plus oats (Group FO). The researchers also provided mares with a commercial vitamin and mineral mix, limestone, and salt daily. After a 29-day trial period and a three-day washout, the mares switched diets so that each consumed both diets.

On Day 21 of each study period, the researchers transported the horses for 100 kilometers before and after the mares performed an exercise test simulating a trotting race (the transport test, or TT). The mares did a second similar exercise test on Day 26 of each period but were not transported before or after (the control test, or CT). The team measured horses’ water intake and heart rates, along with collecting blood samples at various intervals pre- and post-exercise for 24 hours, before the first and after the second transport or at similar time points while CT horses remained in their stalls