Probiotic supplementation in trained trotter horses. effect on blood clinical pathology data and urine metabolomic assessed in field

The attention of sports com- munity toward probiotic supplementation as a way to promote exer- cise and training performance, together with good health, has in- creased in recent years. This has applied also to horses, with prom- ising results. Here, for the first time, we tested a probiotic mix of several strains of live bacteria typically employed for humans to improve the training performance of Standardbred horses in athletic activity. To evaluate its effects on the horse performance, we mea- sured lactate concentration in blood, a translational outcome largely employed for the purpose, combined with the study of hematological and biochemical parameters, together with urine from a metabolomics perspective. The results showed that the probiotic supplementation significantly reduced postexercise blood lactate concentration. The hematological and biochemical parameters, together with urine mo- lecular profile, suggested that a likely mechanism underlying this positive effect was connected to a switch of energy source in muscle from carbohydrates to short-chain fatty acids. Three sulfur-containing molecules differently concentrated in urines in connection to probi- otics administration suggested that such switch was linked to sulfur metabolism.