Fat adaptation in horses involves interval training and feeding a high-fat diet to improve mitochondrial oxidation of fatty acids. This adaptation results in sparing the use of glycogen and glucose, improving stamina and possibly sprinting ability. It also leads to a protective effect against certain types of tying-up.
In a presentation at a Kentucky Equine Research nutrition conference, speakers shared findings from various equine fat adaptation studies:
- Preference tests demonstrated higher palatability (voluntary acceptability) of corn oil compared to other vegetable oils and animal fats.
- Spontaneous activity and reactivity were lower in horses fed diets fortified with corn oil or mixtures of soy lecithin and corn oil.
- The speed at which blood lactate concentration began to increase sharply during an incremental exercise test was higher in fat-adapted horses than in controls. This submaximal test could be used to predict the metabolic potential of an unfit horse and to monitor fitness of horses in training.
- In fat-adapted horses, blood lactate concentration was higher during anaerobic work but lower during aerobic work. These results suggest that glycolysis is enhanced during anaerobic work, which would enable sprinting, but suppressed during aerobic work, which would confer stamina.
- Lower CO2 production in fat-adapted horses during strenuous exercise would reduce the mechanical effort of respiration, a beneficial change for horses with mildly compromised pulmonary function, especially in hot and humid conditions.
- Exercising horses fed a hay:oats:oil (45:45:10) diet compared to hay and oats (50:50) produced less heat per day, required less water, and carried about 12 kg (26 pounds) less dead weight in the large bowel. Thus, fat-adapted horses may stay cooler and need to move less body weight during exercise, but they also have less water available for absorption from the hindgut, a possible disadvantage in some equestrian disciplines.
Kentucky Equine Research has developed a dietary supplement, EO-3, that delivers long-chain omega-3 fatty acids in a palatable liquid form. Benefits include support of the immune system, enhanced bone metabolism and development, and regulation of gene expression to positively affect insulin sensitivity. Omega-3 fatty acids also increase the flexibility of red blood cell walls, reducing the risk of exercise-induced pulmonary hemorrhage.