Article by Kentucky Equine Research Staff

Mineral Content of Pasture Affects Hoof Composition in Foals

March 14, 2022 By Kentucky Equine Research Staff

Rife with nutrients, high-quality pasture provides horses with many essential minerals, especially when grown in rich soil. Nutrient deficiencies in soil, however, can lead to pasture grasses with mineral shortages. A classic example involves low-selenium soils giving rise to low-selenium forages. Deficiencies can then carry over into body tissues. Researchers evaluated the calcium, copper, and zinc concentrations in soil and pasture and then compared them to concentrations found in the hoof capsules of foals.^*

Sampling of soil, pasture, and hoof capsules occurred in two periods. The first happened in summer and fall when all foals, between one and six months of age, were still nursing their dams; the second occurred after weaning when foals were nine to 12 months old. Forty-one foals were used in the preweaning period, 28 in the postweaning period.

All foals used in the study were Criollo, a South American breed revered for its tractability, soundness, and stamina under saddle. Mature height tends to be between 14 and 15 hands, and most are considered easy keepers. Foals were born and raised on five farms in Brazil. Mares and foals grazed native pastures consisting primarily of bahiagrass, kaimi clover, blanket grass, dallisgrass, and bermudagrass, though hundreds of other pasture species were likely part of the grazing landscape. They received no concentrate or mineral supplementation.

Prior to sampling, hooves were scoured with a mineral free-detergent and dried with anhydrous ethanol. Using a hoof rasp, 2-g samples were collected from the front of the hoof wall, about 1 cm below the coronary band.

At the same time as hoof sampling, researchers collected pasture samples. Seventeen 1-kg samples were collected every season from the pastures grazed by mares and foals. Soil samples were also collected from each of the five farms.

In the end, researchers observed that the “levels of calcium, copper, and zinc in the hoof capsule during the preweaning and postweaning stages are influenced by the season and different physiographic regions.” More specifically, researchers found no association between calcium concentration in the hoof walls and in pasture from different regions. Contrarily, the copper concentration of the hoof and pasture in preweaning and postweaning, as well as zinc in preweaning, were positively associated. In regard to season, calcium and zinc were higher in both hoof and pasture samples in summer and spring, respectively, yet in autumn the concentration of copper increased. The lowest concentration of these minerals in hoof samples were observed in winter.

“While this study investigated the mineral concentration of hoof samples collected from pasture-raised foals south of Earth’s equator, hoof health is a concern for horse owners the world over, no matter the breed, age, or use,” said Catherine Whitehouse, M.S., a nutritionist at Kentucky Equine Research. “This research emphasizes the importance of a properly balanced diet in the formation of resilient hoof tissue even at a young age.”

A well-balanced diet often confers all of the nutrients needed for healthy, strong hooves. Whitehouse knows well, nevertheless, that some horses benefit from supernutritional hoof support. “Walk in any boarding or training barn that places high importance on nutrition, and you’ll likely find hoof supplements. But, as a caveat, selecting the right supplement is imperative.”

The “right supplement,” according to Whitehouse, is one that contains not only biotin, the nutrient most notably aligned with revamping weak hooves, but also other important nutrients: the amino acid methionine, organic zinc, and iodine. Look for high-quality hoof supplements that are manufactured by reputable companies, especially those with an active research program.

“Even high-quality supplements are not a panacea for all horses,” Whitehouse explained. “While the hooves of many horses respond to supplementation, others don’t, but it’s the only avenue of investigation after other potential causes of poor hoof health are ruled out, namely mistakes in farriery and ration formulation.”

^*Silva, P.M., J.L.S. Silva, D.H. Bonemann, A.S. Ribeiro, L.O. Silva, G.L.B.L. Pizzi, and C.F. Martins. 2022. Influences of the seasons of the year and physiographic regions on the levels of calcium, copper and zinc in the hoof capsule of foals pre- and postweaning and raised in native pasture. Equine Veterinary Journal 109:103854.

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