Effect of dietary vitamin E supplementation on the integrity of skeletal muscle in exercised horses.

The research investigates how different levels of supplemental vitamin E affect the muscle integrity in exercised horses. Various indicators of muscle integrity were monitored over an experimental period of 90 days, where horses were maintained on three distinct diets: no vitamin E supplement, supplement of 80 IU vitamin E/kg DM, and supplement of 300 IU vitamin E/kg DM.

Research Methodology

• The study included a total of 19 horses, categorized by sex, and then randomly assigned to one of the three different dietary supplements.
• The base diet (BASAL) contained less than 44 IU of vitamin E per kilogram of dry matter (DM) but met all other nutritional requirements.
• Throughout the 90-day experimental period, the horses underwent regular exercise for five days each week. Researchers measured both serum and middle gluteal muscle alpha-tocopherol concentrations at the outset of the trial, and then after 30 and 90 days.
• At the end of the trial, all horses performed a repeated submaximal exercise test (RSET) and various measures including alpha-tocopherol, thiobarbituric acid reactive substances (TBARS), conjugated diene (CD) concentrations in the middle gluteal muscle, and serum creatine kinase (CK) and aspartate aminotransferase (AST) activities were taken before and after RSET.

Key Findings

• The horses receiving the BASAL and 80 IU vitamin E supplement diets were found to have decreased serum alpha-tocopherol concentrations over the course of the 90-day treatment period. This contrasted with the horses receiving a 300 IU vitamin E supplement, who maintained consistent alpha-tocopherol concentrations throughout.
• The horses fed the 300 IU supplemented diet showed notably higher serum and muscle alpha-tocopherol levels after 30 and 90 days when compared with the horses fed the BASAL and 80 diets.
• Results also showed increases in serum CK and AST activity after RSET, regardless of the vitamin E supplementation levels in the horse’s diet. This suggests that the level of dietary vitamin E supplementation did not influence these particular enzymes.
• The level of muscle alpha-tocopherol was found not to affect muscle CD or TBARS, which are both indicators of oxidative stress.

Conclusion

• This study provides insight into how dietary vitamin E supplementation might impact muscle integrity in horses. Notably, it showed that a higher supplemented dose (300 IU/kg DM) maintained consistent alpha-tocopherol levels and higher serum and muscle alpha-tocopherol concentrations. It did not appear to affect CK, AST, CD, and TBARS measures, and thus further research is needed to understand the specific impact of vitamin E supplementation on muscle function and integrity.