Acetyl L Carnitine (ALCAR) Supplement for Horses Mad Barn Horse Antioxidant & Metabolic Boost Acetyl L Carnitine Foxden Equine NEW! Boost your horse's energy, stamina, and recovery with EnduraBoost! This concentrated performance supplement, enriched with L carnitine, provides that extra boost when your horse needs it. With the added benefit of Postbiotics, L Carnitine is amino acid supplement that enhances energy production in performance horses. It works through 6 ways: Muscle level of L Carnitine influence the exercise capacity of a horse. L