Copper and zinc balance in exercising horses fed 2 forms of mineral supplements.

The research article is about a comparative study on the absorption and retention of copper, and zinc in horses using two forms of mineral supplements: inorganic sulfate and organic chelate.

Objectives and Methodology of the Study

• The primary objective of this study was to examine and compare the absorption and retention of copper (Cu) and zinc (Zn) in horses undergoing moderate-intensity exercise and being supplemented with either an inorganic sulfate (CuSO(4) and ZnSO(4)) form or an organic chelate form (Cu-Lys and Zn-Met) of the minerals.
• For this study, nine mature horses were used in a seven-period, 28-day modified switchback design experiment.
• The horses were subjected to a controlled ‘mineral repletion-depletion’ diet sequence prior to introduction of the experimental diet to ensure a standardized mineral status across all horses.
• The experimental diet provided 90% of the 1989 National Research Council (NRC) recommendations for Cu and Zn, comprised of a 50/50 blend of concentrate and hay and designed to meet the energy, protein, calcium, and phosphorus needs of moderately exercising horses.
• The researchers collected and analyzed feed, urine, water, and fecal samples during the last four days of the experimental periods to measure the apparent absorption and retention of Cu and Zn from the two mineral supplements.

Key Findings

• The study found that horses fed the organic chelate diet ingested approximately three times more Cu and Zn compared to those fed the sulfate-supplemented diet, causing a higher intake and fecal excretion.
• All horses showed negative values for apparent absorption, with Cu absorption and retention as a percentage of intake being greater for horses fed the organic chelate diet. However, the cause of the excessively high fecal and urinary excretion values of Cu and Zn were beyond the comprehension of the researchers.
• Despite these anomalies, the study managed to establish that Cu-Lys was absorbed more efficiently than CuSO(4).
• No significant difference was observed in the absorption of Zn-Met and ZnSO(4).

Implications of the Study

• This research provides an invaluable insight into the absorption and retention of Cu and Zn in horses, important for establishing optimum feeding strategies for maintaining the health and performance of active horses.
• However, the unusually high fecal and urinary excretion values for Cu and Zn present in this study have led the researchers to interpret their results with caution, underscoring the need for further research in this area.