Young Horses Need More Zinc, Copper For Strong Skeletons, Says UF Expert

April 4, 2002

GAINESVILLE, Fla. — They run fast and jump high, sometimes suffering torn cartilage and broken bones as a result.

They’re not human athletes, they’re horses. And a University of Florida expert says current national nutrient recommendations may not provide all the zinc and copper the animals need to develop strong cartilage and bone in their early years.

“The entire equine industry is based on athleticism, whether we’re talking about horses used for racing, show or pleasure riding,” said Ed Ott, animal sciences professor with UF’s Institute of Food and Agricultural Sciences. “The skeletal system is literally the foundation for a healthy, capable animal.”

A 1989 National Research Council report, considered the “gold standard” for equine nutrition, recommends that growing horses get 40 milligrams of zinc and 10 milligrams of copper per kilogram of feed. But recent UF research shows foals 5 to 18 months old develop the strongest bones when given feed containing double those amounts, Ott said.

Both minerals are used for enzyme processes in forming and maintaining cartilage, and zinc is also involved in mineralization of cartilage, the process by which cartilage is replaced by bone in developing horses.

In light of the findings, Ott, who headed a panel of experts that issued the report, said the recommendations should be revised in order to help reduce the incidence of fractures and other skeletal injuries to horses.

In 1999, Ott and other equine nutrition experts met to discuss recent research, said Charlotte Kirk Baer, director of the council’s Board on Agriculture and Natural Resources in Washington, D.C.

“Their consensus was that the report should be revised,” Kirk Baer said. “We’re all in favor of that, it’s mainly a question of when the funding becomes available. Because the council is a private entity, its projects are dependent on funding from the federal government, foundations and industry sources.

“Unfortunately, several federal agencies have made cutbacks in their allocations to the council,” she said. “We’re concerned that perhaps the agencies aren’t aware of the tremendous value that industry and the general public place on these reports.”

Early next year, the council will issue an updated report on nutrient requirements for dogs and cats, she said.

The council’s recommendations for horses are important to feed producers and others with a professional interest in equine nutrition, said Larry Mack, nutritionist with Seminole Feeds in Ocala.

“The report is certainly a base of information, although it’s not the only thing we look at,” Mack said. “The council tends to be pretty conservative and makes recommendations based on the most thoroughly reviewed findings, whereas we try to be a little more cutting-edge in order to stay competitive.”

He said commercial horse feeds often are fortified with zinc, copper and other minerals. Many Seminole feeds contain 120 milligrams of zinc and 40 milligrams of copper per kilogram.

Ott said that recreational horse owners may want to consider the proper supplementation of their grazing animals.

“You can’t assume that forage will meet 100 percent of a horse’s nutritional requirements,” he said. “You may have problems if the soil is deficient in some nutrients, or there aren’t enough plant species available to provide a balanced diet.”

Zinc and copper are considered trace minerals, because horses need them in minute amounts, Ott said. A 6-month-old foal weighing 235 kilograms would need about 472 milligrams of zinc and 118 milligrams of copper per day.

“Prior to birth, the skeletal systems of horses and other vertebrates are composed entirely of cartilage,” he said. “In horses, much of the mineralization process occurs between birth and 1 year of age, and mineralization isn’t complete until 3 to 4 years.”

To conduct the research, Ott worked with graduate students at UF’s Horse Research Center near Ocala. They provided foals with varying amounts of zinc and copper and used X-ray technology to estimate bone mineral content and skeletal strength.

“We used non-invasive procedures so that we could work with the same foals as they matured,” he said. “For horses, the most critical time in skeletal development is between 5 months and 18 months, when their bodies are growing fastest.”

He said future UF research will examine the roles zinc and copper play in skeletal development of younger and older horses.