By: Shannon Pratt-Phillips, Ph.D.
Equine nutritionist Shannon Pratt-Phillips, Ph.D. dishes on feeding for healthy feet.
I wish good feet were as simple as providing good nutrition. What good nutrition can do, is provide the optimal nutrients for the framework of the hoof. However, nutrition can’t change genetics or conformation, or decrease the importance of a good farrier.
The hoof wall capsule extends from the coronary band below the pastern to the ground, which surrounds and supports the inner structures of the hoof. The hoof wall grows down from the coronary band at a rate of ~1/4 – 3/8 of an inch per month. Damage to this area, or poor nutrition, can affect hoof growth and quality. In fact, hoof quality is one thing that nutritionists can use to evaluate overall nutritional status, in addition to coat quality. The relatively high turnover of these tissues allows for nutritional deficiencies to be more obvious (vs bone density or liver vitamin status, for example).
The first step to improve hoof quality is providing a balanced diet. There are some key nutrients that are components of the hoof and should be in your horse’s diet. Luckily, if you’re feeding enough of a good quality hay and some kind of vitamin-mineral supplement, ration balancer or commercial feed, you’re probably already doing the best you can to ensure that nutrient requirements are met.
To ensure hoof health, your horse should be in good body condition; that is, consuming enough calories for him to have good fat coverage over the body. But, of course, not be too fat, otherwise there is added strain on the hoof to support body weight. A horse that is not consuming enough calories will put the calories he does get toward more essential functions (such as keeping the heart beating) and will direct less toward building new tissues.
A horse that is consuming good quality pasture (high in protein, calcium and beta-carotene), has access to a trace mineral salt source (for zinc) and water, likely has meets the National Research Council’s (2007) nutritional requirements of horses, which includes hoof health. Horses that are kept on hay, or have higher demands, will likely be fed some kind of commercial feed or ration-balancer that contains the key nutrients (described in the sidebar on page 19) at the levels required by those horses. But what about feeding supplemental nutrition above the NRC’s suggestions? Can that improve equine hoof health further? The only nutrient that has been shown to have an impact on hoof quality when fed at levels above the NRC’s requirements is biotin. Of course, this is of interest seeing as horses are rarely deficient in this vitamin, but research has shown that horses with poor hoof quality see improvements when supplemented with 20mg of biotin per day. Another study did report that horses that were fed copper and zinc in a proteinated form (attached to an amino acid) had increased hoof growth over horses supplemented with inorganic forms of these minerals. It is presumed that these chelated mineral complexes have better availability than inorganic forms, so it remains unclear if there would have been a difference between the two groups if the amount of mineral absorbed was the same.
Most commercial supplements contain biotin, zinc and copper (to balance the zinc), as well as some additional amino acids such as methionine and/or cysteine. The key with trying a hoof supplement is to remember that it takes almost a whole year for the hoof to replace itself, so it requires several months supplementation to see any potential benefits.
Nutrients Needed to Grow Healthy Hooves
Protein intake is important, and protein requirements are generally easily met through the provision of good quality hay. However, there may be some key amino acids (the building blocks of protein) that might be limited if hay is the only source of protein in the diet. Lysine is considered the first limiting amino acid, because it is required in amounts that may be limited in traditional horse feeds. Lysine is an important component of many structural tissues within the body and is essential for hoof health. The hoof wall is made up mostly of a protein called keratin. Keratin contains a large percentage of the sulfur-containing amino acid, cysteine. Sulfur is important in producing crosslinks within the strands of keratin to increase its strength. Cysteine can be made within the body (it is not essential in the diet) provided there are adequate amounts of the amino acid methionine (which is essential in the diet). Soybean meal is an excellent source of these amino acids and is typically an ingredient in most commercial feeds and ration-balancers. Alternatively, these amino acids may be added individually to a commercial feed mix. Essential fatty acids, such as linoleic acid (18:2, omega-6) and α-linoenic acid (18:3, omega-3) are important for forming a permeable barrier on the outer layer of the hoof to prevent drying and cracking. Soy and corn oil is a good source of linoleic acid, while flaxseed oil is a good source of α-linoenic acid. These are also often incorporated into equine feeds.
Calcium is an important cofactor for the enzymes that cause epithelial cells to become keratinized and aids in the formation of sulfur-sulfur bonds. Hay is often a good source of calcium, and is also included in equine feeds. Zinc is also considered to play a role in normal hoof health, as white line disease has been shown to be more common in horses on zinc-deficient diets. Vitamin A (found in pasture and hay has beta-carotene, and supplemented directly in equine feeds) plays a role in the integrity of the epidermal cells (skin) that become keratinized to form the hoof wall.
Biotin is an essential cofactor for the enzymes that are involved in the keratinization process, and plays a role in general protein synthesis. Biotin is one of the B vitamins that are produced by microbial organisms within the horse’s digestive tract, and deficiency is very rare in the horse.