.Vervolg :
Selenium, Vitamin E--Function in cell membrane protection, and they act as antioxidants.
Biotin--Important in intercellular cementing substance for cell-to-cell adhesion in the outer hoof wall. "Biotin is probably stamped on the front of every hoof supplement out there, but you have to understand the entire process to understand how it helps," Swenson said. "Think of a brick wall. Biotin functions like the mortar holding the bricks together. More biotin can give you better mortar, but you still need good, solid bricks from other nutrients.
"The horse produces some biotin during hindgut fermentation," she explained. "Deficiency is tough to produce. There has been no difference demonstrated between plasma concentrations of biotin in horses with good and bad feet. It seems to be most effective on stratum externum (outer hoof wall) defects, such as in horses with shelly, brittle hoof wall. Toxicity is nonexistent due to efficient elimination in the urine."
Manganese--Deficiency causes abnormal bone and joint development, impaired ability to make or repair joint cartilage, and abnormalities in skin, hair, and hooves. "Foals which lacked manganese during gestation knuckle over," said Swenson. Forages normally have adequate levels, but availability is often minimal. Toxicity has not been reported in horses.
Selenium--This nutrient is more “touchy” than others; chronic toxicity (possibly caused by supplementing this nutrient to a horse which doesn't need it) can cause lameness, cracking and sloughing of hooves, and loss of mane and tail hair. Deficiency can cause muscular cramping, poor stress tolerance, impaired immunity, and subpar performance.
"Some say this was one factor in Custer's demise--traveling through the South Dakota area where soils are very high in selenium (resulting in problems with his horses)," Swenson commented.
Vitamin A--Involved in maintaining epithelial tissue integrity. Deficiency is rare, she said, but occurs when grain and poor-quality hay are fed; inflammation of the coronary band is a result. Plant sources of Vitamin A are usually adequate. One can't create toxicity with beta-carotenes, but it is possible with supplements that contain retinyl palmitate or retinyl acetate. The clinical signs of toxicity include fragile bones and abnormal bone deposits in the body.
In summary, Swenson stated that building the hoof starts at the cellular level. "Understanding the role of nutrients and how they relate to growth, maintenance, and repair is critical for decision making. Balanced nutrition is the key--feeding high levels of one or more nutrients disrupts the balance."