Nutritional Ergogenic Aids in Horses: What Are They and Do They Work? | Equinews

Nutritional Ergogenic Aids in Horses: What Are They and Do They Work?By Kentucky Equine Research Staff · February 12, 2013

Correct nutrition is vital in supporting athletic performance for humans and horses, and horse owners try to select the best hay and concentrate for their feed management program. But wouldn’t if be wonderful if you could just add something extra to your horse’s feed tub that would make him stronger, faster, and able to perform for longer periods without getting tired? Humans have long sought this type of result-boosting nutritional shortcut for themselves and their horses, and sports magazines and catalogs often tout a new supplement or capsule backed by the promise of a nearly miraculous increase in ability.

Dietary additives that claim to have a performance-enhancing effect fall into the category of nutritional ergogenic aids. The body of research on the effectiveness of ergogenic aids is very small, even when animal and human studies are considered together. Some of the human studies have been designed in ways that make it impossible to make a fair and unbiased comparison between treated and untreated individuals that have been tested under the same conditions. Animal studies must also be conducted in a situation where the handlers are blind to the treatment. This requirement is especially important in equine studies where riders or drivers can have a huge impact on the performance of the horse.

Conclusions relative to the efficacy of a particular treatment should be based on sound statistical methods. However, in many performance situations this practice is problematic. First, it is essential to be able to accurately measure “performance.” Second, it is essential that differences detected as statistically significant are also biologically significant, and that biologically significant effects can be detected statistically. A one or two second change in race time would be considered biologically significant by most trainers but might be difficult to identify as statistically significant without a large number of animals or repetitions.

When tested in a research environment, some ergogenic aids or practices appear to have a positive effect on some subjects but the differences between the treated group and the controls are not statistically significant at the conventional 5% level of acceptance. This situation occurs because performance criteria are often subject to great variability resulting from individual differences. Because of limited resources, many studies are restricted to such a small number of subjects that it is often unrealistic to expect to find a performance difference that can be identified at the 5% level of significance. Although this level of significance is a good discriminator for most experimental studies, in studies with small sample sizes it may be useful to select a different level of significance for testing hypotheses. At the very least, when treatments produce changes that are different at 0.1 > p >0.05, follow-up research is warranted.

Another problem associated with these types of studies is the lack of dose response information that leads to difficulty in selecting the appropriate treatment rate and adaptation period. Because of the limited number of studies that have been performed and the difficulties involved in conducting those studies, contradictory evidence exists for almost every ergogenic aid. In addition, very few substances have been tested with adequate controls in real performance situations. Particularly with horses, it is difficult to translate laboratory results obtained under controlled circumstances to potential effects on the race track or in the show arena. In a perfect world, each ergogenic aid would be tested in a laboratory situation to identify metabolic and physiological functions, ideal dose rate, and adaptation period, and then tested in the field to identify actual performance effects. Since it is not a perfect world, assessment of the value of ergogenic aids must be made on the information available and on new information. The following is a brief discussion of B vitamins and hematinics (blood builders), two of the more common nutritional supplements reputed to have an ergogenic benefit in horses.

In human studies, deficient vitamin intakes (combined B1, B2, B6, and C) have been reported to have a negative impact on physical performance, even though general health was not affected. One study showed that thiamin supplementation increased the anaerobic threshold in cyclists. The normal equine diet contains most B vitamins, with the exception of B12, which can be synthesized and absorbed in the gut. The microbial population in the large intestine is also capable of synthesizing other B vitamins, including thiamin. It has generally been accepted that the levels of B vitamins provided by typical diets and microbial synthesis are not deficient for horses. However, the absence of classical vitamin deficiency signs does not necessarily imply optimal vitamin status. Because of its role in the conversion of pyruvate to acetyl COA, thiamin has received particular attention as an ergogenic aid. Over the years, the National Research Council has increased the recommendation for thiamin based on research results. In one study where three horses received three levels of dietary thiamin, blood lactate levels following 30 minutes of exercise were lower in horses receiving the highest level of thiamin, but the lactate levels were relatively low (below the proposed anaerobic threshold) for all treatments. Horses receiving the highest dose of thiamin excreted significantly more thiamin in the urine and were in positive thiamin balance. None of these results can be used to prove that vitamin B supplementation definitely leads to better performance in horses.

Hematinics are used to a large extent in the horse industry, although there is very limited research support for this practice. The compounds in this category (used alone or in combination) include iron, copper, zinc, pyridoxine, B12, and folic acid. These nutrients are involved in hemoglobin synthesis and erythropoiesis. The availability of adequate hemoglobin is essential for oxygen transport. In humans, a hemoglobin concentration of 15 to 16 g/dL is considered a desirable level for optimal performance, and low levels will impair maximal oxygen transport.

The occurrence of “sports anemia,” a decrease in hemoglobin levels in athletes, has been described in humans where this condition may occur as a result of increased plasma volume in response to training, or from depleted iron stores and increased hemoglobin losses due to exercise. There is some indication that horses can suffer a decline in hematologic parameters during a training program, but the source of this decline has not been defined.

Human athletes, especially women, may have marginal iron intakes and appear to benefit from iron supplementation. It has been suggested that endurance athletes can also benefit from supplementation with zinc, folate, pyridoxine, B12, and ascorbate in addition to iron. Iron deficiency in horses appears to occur rarely under practical feeding conditions. One study found little response of equine hematological parameters to various hematinics. Another reported that performance horses on typical diets in Queensland were probably B12 adequate but might require additional folate.

Comparisons of hematological parameters and responses to exercise in horses and humans must be made carefully because distinct differences exist between the two species. Horses store a large percentage of their red blood cells in the spleen. During exercise, splenic release of stored cells can increase packed cell volume and hemoglobin values by 50% or more. The spleen does not function similarly in humans. Consequently, measures of hemoglobin taken at rest are relatively representative of the hemoglobin that will be available during exercise in humans, but not in horses. Any small increase in resting hemoglobin produced by a hematinic in horses would be overshadowed during exercise by the increase resulting from splenic release of red blood cells.

Information in this article was taken from a presentation by Laurie M. Lawrence, Ph.D. The full text of the presentationcan be found in Advances in Equine Nutrition.

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