Both zinc and copper have important roles in growth and connective tissue health, making them especially critical for growing animals. | Photo: Anne M. Eberhardt/The Horse

Zinc (Zn) and copper (Cu) are dietary trace minerals with different functions in the body, but they are often discussed together. That’s because they use the same “vehicle” for absorption from the digestive tract into circulation and compete for a ride on that vehicle. As such, horses must consume Zn and Cu in proper amounts so that one mineral doesn’t outcompete the other.

The National Resource Council’s Nutrient Requirements of Horses (2007) recommends that Zn and Cu be fed in a 4:1 ratio (4 parts Zn to 1 part Cu) for mature horses to ensure proper absorption of both minerals.

Zinc

Zinc is part of over 100 different enzymes in the body, many of which participate in protein and carbohydrate metabolism. The highest Zn concentrations are found in the iris and choroid (between the sclera and retina) of the eye, pancreas, hoof horn, liver, and