The connective tissues of all mammals are rich in the mineral sulfur. The skin, hair, ligaments, tendons, cartilage and the hooves of horses are primarily collagen. Collagen is the protein of connective tissue, and is the most abundant protein in the mammalian body. Sulfur depletion is known to lead to connective tissue problems; however on the other hand too much sulfur in the diet may have a negative effect on connective tissue strength.
Amino Acids combine to make Protein
There are twenty amino acids known that make up the building blocks for mammalian body protein. Approximately one-half of the amino acids are essential amino acids in which the body is unable to make these amino acids and therefore they must be ingested. Methionine is an essential amino acid that can also be converted by the body to another “sulfur containing” amino acid called cystine. Cystine is important because it furnishes the sulfur “welds”, or crosslinks, that are necessary for healthy collagen and thus strong hoof infrastructure. A deficiency of sulfur containing amino acids could lead to structural weakness of the ligaments, tendons, bones, joints, and hooves.
Since methionine and cystine are naturally occurring “sulfur containing” amino acids they are considered “organic” forms of sulfur. The organic forms of sulfur supply the majority of sulfur to meet the horse’s sulfur requirement. Plants provide both inorganic and organic sulfur to the horse; however the inorganic sulfur is poorly absorbed by the horse’s digestive tract. The majority of sulfur a horse utilizes is derived from the organic sulfur of methionine and cystine in the amino acids of plant proteins. The equine hindgut microbes may utilize some inorganic sulfur in the synthesis of their cellular proteins but the absorption of these amino acids is compromised at this point in the digestive tract.
It is the opinion of the authors of this article that due to the differences in absorption and utilization between organic and inorganic sulfur the daily sulfur requirement of a horse is difficult to accurately determine. The daily sulfur requirement must be based on organic sulfur rather than the organic and inorganic sulfur intake. Horses with connective tissue problems and poor hoof quality have been shown to benefit from DL–methionine supplementation. DL-methionine is a form of methionine that can provide sulfur for multiple metabolic functions. Unpublished research by Life Data Labs, Inc has determined an effective daily level of DL-methionine supplementation is 5 to 8 grams for a 1000 lb horse with poor hoof quality.
Hoof Supplements, Joint Supplements, MSM and Sulfur
Many hoof supplements contain organic sulfur in the form of the essential amino acid methionine in order to balance the relative deficiency of this amino acid in typical equine feedstuffs. If the horse has joint problems in addition to hoof problems, joint supplements containing glucosamine, hyaluronic acid, chondroitin sulfate and/or avocado extracts can be given in addition to the hoof supplement. Keep in mind that a quality hoof supplement will likely help the joints since both hooves and joints are composed of connective tissues, thus eliminating the need for a joint supplement!
Many but not all joint supplements also contain MSM, or methylsulfonylmethane. MSM contains about 34% sulfur manufactured via a chemical reaction involving DMSO (dimethyl sulfoxide) and hydrogen peroxide.The resulting MSM is chemically identical to the MSM that is found in small quantities in natural plant materials. A refinement process is necessary to remove any impurities or toxic by-products from the MSM following the chemical reaction.
Excessive dietary sulfur can result from either MSM supplementation, excess supplementation with the sulfur containing amino acids methionine and cystine, or a combination of MSM / methionine / cystine supplementation. Excess sulfur in the diet has been shown to block proper absorption of copper in many species. Copper, along with vitamin C, is necessary for the formation of collagen to build the healthy connective tissue essential for strong hooves and joints.
There are other negative effects of over supplementation with many nutrients, and it is generally not a good idea to give more than one vitamin/mineral supplement to a horse. Giving a balanced supplement backed by research and years of proven effectiveness and avoiding other supplements with duplicate nutrients can lead to a healthier and happier horse.
With special thanks to -
J. Frank Gravlee, DVM, MS, CNS
Founder of Life Data Labs, Inc.
Developer of Farrier’s Formula®
Co-authored by H. Scott Gravlee, DVM
Equine Nutrition Consultants