Effects Of Exercise Training On The Digestibility And Requirements Of Copper, Zinc And Manganese In Thoroughbred Horses

Hudson, C., J. Pagan, K. Hoekstra, A. Prince, S. Gardner and R. Geor. 2001. Effects of exercise training on the digestibility and requirements of copper, zinc and manganese in Thoroughbred horses. In: Proc. 16th Equine Nutr. and Physiol. Soc. Symp. pp. 138-140.

Very little research has been conducted to determine the trace mineral requirements for athletic horses. Preliminary studies in our laboratory demonstrated a significant increase in urinary Se excretion after a single bout of exercise, suggesting that regular exercise and training may increase Se requirements. The objectives of this study were to 1) determine the digestibility and retention of copper, zinc and manganese over four different levels of intake (basal, 50% of NRC added, 100% of NRC added, and 200% of NRC added) and 2) determine how regular exercise and training alters the requirements for these trace minerals. Six mature Thoroughbred geldings [3 sedentary (SED) and 3 horses in regular exercise training (EX); mean age 11.2 +/- 2.6 yr, body weight 534 +/-46 kg] were studied in a 16 week longitudinal experiment that consisted of 4 periods, each with a 23-day adaptation period followed by a 5-day complete collection digestion trial. In period 1, horses were fed a diet of unfortified sweet feed and timothy hay (basal intake) that provided approximately 85%, 160% and 65% of the NRC recommendations for Cu, Mn and Zn, respectively. Results of the present study suggest that exercise training results in a higher requirement for Zn, but does not affect the true digestibility and maintenance requirements of Cu and Mn in mature Thoroughbred horses.

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