Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find Part 1 of the latest question and answer installment that you can share with your footcare clients.
Q: What role do fats and waxes play in the equine diet when it comes to hoof quality?
A: The outermost layer of the hoof wall (stratum externum, aka periople) contains a variety of fats and waxes, as does the “hard”/dead portion of the hoof wall. The stratum externum grows down from the epithelial cells of the periople, which are located below the coronary band. While the hardest layers of the external hoof have the highest molecular weight of keratin, equally important are the fatty substances.
When present in correct amounts in an unbroken layer, fats and waves seal moisture into the deeper hoof structures and seal out water. The major fat is cholesterol sulfate, which is a polar lipid. Like the phospholipids in cell membranes, these molecules form a double layer.
“Polar” means one end is attracted to fat, while the other end is attracted to water. These molecules line up with their fat loving/water hating tails facing each other and their water loving heads exposed to the outside and inside. Other polar phospholipids (the ceramide family) are also present.
The “soft” horn — the white line area — contains less fat and more squalene, which is a precursor for cholesterol. Its higher levels in this area may mean that it contributes to cholesterol content in the horn. Or the higher squalene level could result in a softer, more fluidly trap around the cells, allowing the growing hoof wall to slide down easier.
Various fats and waxes fill the spaces between the keratinocytes, which are the cells producing keratin. They give the outer layer of a healthy hoof a naturally slick feel and shine. There’s no problem with synthesizing cholesterol, or the phospholipids and other fatty substances in the hoof, as the “fat deficiency” per se is not an issue. However, the alteration of dietary fats can change the composition of the fats in the hoof wall.
A September 1998 Equine Veterinary Journal article looked at the effect of a supplementary dietary evening primrose oil mixture on hoof growth, hoof growth rate and hoof lipid fractions in horses. Conducted by Royal Army Veterinary Corps members at the Defense Animal Center in Melton Mowbray at Leicester in the United Kingdom, the lipid chemistry of the normal equine hoof, together with the effect of oral supplementation with an evening primrose oil mixture (EPOM) on its growth, growth rate and lipid content was assessed in a controlled and blinded feeding trial. Twelve horses were paired as closely as possible according to sex, age, weight, height and color and then one from each pair was randomly allocated to treatment or control groups. The treatment group received 30 ml of oral EPOM/day, otherwise the nutrition and management regimes were the same for all horses.
No significant differences were seen between treatment and control groups for hoof horn growth or growth rate. However, there was a significant difference in hoof horn growth within the treatment between 4-8 weeks after the start of supplementation.
White line disease has become a more common disease bit and has led to a near epidemic of intensive hoof treatments/soaks in a variety of products, ranging from a few days a week to several times a day. More often than not it does not have the desired effect, as the horse did not have white line disease in the first place.
It’s not immediately obvious from that study whether the changes were good, bad or of no consequence. However, they do show the composition of fats in the diet will influence this important component of the hoof wall. What we need are long term studies looking at fat from all sources on various diets, including grazing, and then comparing the data to hoof wall quality.
Dr. Eleanor Kellon, a staff veterinary specialist for Uckele Health & Nutrition, has been an established authority in the field of equine nutrition for over 30 years. The owner of Equine Nutritional Solutions in Robesonia, Pa., she is a founding member and leader of the Equine Cushing’s and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via integration of research and real-life clinical experience. Prevention of laminitis is the group’s ultimate goal.
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Click here to read Part 2 of the Nov. 1, 2019 installment: What are the major causes of laminitis concerns during the fall months?