Vitamins and Minerals Guide for Horses

Last Updated on August 21, 2023 by Allison Price

Find out how to get the most from what we know about your horse’s vitamin and mineral requirements.

Super Steed vitamins are on sale at your local vitamin and feed store. This is almost half the cost of the “Performance Lift”, which you normally give to your horse each day. What can you do? What is the best vitamin supplement?

It’s a great question. Your veterinarian may not know the answer. Truth be told, solid science regarding vitamin and mineral supplementation is still in its infancy. To make a decision on which supplement to buy, you need more than just price comparisons and marketing claims.

I will explain the role vitamins and minerals have in horse health and what basic nutrient requirements are. You may be surprised at how little we know about the needs of your horse. Next, I will tell you what we know about certain vitamins and minerals. I will help you determine which supplementation is best for your horse so that you can make a decision on the right product.

Vitamins and Minerals 101

Vitamins are organic compounds (contains carbon-atoms) that are essential for healthy growth and metabolism. They can only be produced or synthesized by an organism (your horse). Vitamins can have many functions in keeping your horse’s health and functioning. Vitamin D, for example, aids in calcium absorption from the horse’s small intestinale. Vitamin E, on the other hand, helps protect the cells and eliminates damaging free radicals.

Minerals, unlike vitamins, have a distinct definition apart from their function in the body. An inorganic substance (doesn’t contain carbon atoms), a mineral is a stable, at-room temperature, and has an ordered arrangement atoms. In simpler terms, a solid crystal. There are almost 5,000 known minerals. However, only a few are necessary for your horse’s health to function properly. Some minerals are essential, like potassium, which is crucial for keeping your horse’s muscles contracted and his heart pumping.

What about requirements?

There is still much to learn about the specific requirements of many vitamins and minerals. The National Research Council of the National Academies published estimates and based their review of data provided by experts. These requirements are not necessarily determined by specific studies. Therefore, recommendations could change as more information becomes available. In 2007, the most recent NRC requirements estimates were published.

It is difficult to determine if your horse requires supplementation. If so, how much. Your horse’s vitamin and mineral requirements will likely be met if he is healthy and has a regular work schedule. It is rare to have toxicemia. Therefore, the most common recommendation is to give a balanced vitamin-mineral supplement as an insurance policy against potential deficiency. This guide will explain why your horse requires specific vitamins and minerals. It will also show you where they can be found and what you should do to supplement his diet.

Vitamin Guide

Vitamins can be broken down into fat-soluble (dissolves in fat) or water-soluble. A, D, E and K are fat-soluble vitamins. Vitamins that dissolve in fat include vitamin A, D, E and K. Vitamin C and the B vitamins (thiamin, B1, riboflavin and B12; niacin and folacin; pantothenic acid and biotin) are water-soluble vitamins.

Because they have the same function of helping with cell metabolism, the B vitamins can be considered a group. They were initially thought to be one vitamin. However, it was later discovered that each of them has a slightly different chemical structure. Practically, it is important to note that fat-soluble vitamins can cause toxicity and water-soluble vitamins don’t. This guide will show you what you know and don’t know about vitamins.

Vitamin A
What it does. Vitamins A are essential for proper vision function. Vitamin A is essential for proper muscle function and differentiation of cells in growth. It also helps maintain healthy mucous membranes. It also plays a role in reproductive function.

Where it came from: Betacarotene is found in fresh pasture and hay. It is converted to vitamin A. It will be stored in your horse’s liver for several weeks, even after it is no longer available. This will protect you from any deficiency during periods when pasture is unavailable or quality of hay suffers.

Required by a 1,100-pound horse. Approximately 15,000 IU daily (1mg B-carotene equals approximately 400 IU vitamin A).

He might need more: Vitamin supplementation is not necessary if your horse does not have access to green forage. Vitamin A supplementation may be recommended if your mare is having fertility issues or if she is pregnant and has no access to pasture or green hay.

B Vitamins
What they do. The vitamins in this group all play a role in the metabolism of carbohydrates, proteins and fats. They aid horses in obtaining the energy they need from the food they eat.

Where they came from: The bacteria in your horse’s large intestinal tract produces the B vitamins. They can also be found in high-quality pasture or hay.

Horses over 1100 lbs. Supplementation levels have not been determined.

He might need more: If your horse has low-quality hooves then supplementation with 20mg of biotin per day may be beneficial. A nervous horse might benefit from the calming effects of B vitamins.

Vitamin C
What it does. Removes harmful free radicals (unstable molecules or unhappy molecules) from the body. Vitamin C is important in protecting cells and helping to form collagen, which is an important part of the body’s connective tissue.

Where it came from: Vitamin C comes from the liver of your horse.

Required for 1,100-pound horse. No specific requirements. Your horse will produce sufficient amounts of food without supplementation.

He might need more:Vitamin C requirements can rise during stressful times when your horse’s body may not be able meet his demands. Vitamin C doesn’t get well into the horse’s intestinal tract. However, it will be more easily absorbed if it is given in large quantities over a long period of time. A study found that older horses respond better to vaccinations when they are given 20g of vitamin C per day.

Vitamin D
What it does. Helps regulate the excretion and absorption of calcium in your horse’s small intestinal tract. These functions are crucial for maintaining the health of your bones and joints.

Where it came from: Vitamin D is made by the horse’s body when exposed to UV radiation (sunlight). He will likely get his vitamin D requirements met if he walks outside 6-8 hours per day. Good-quality hay also contains Vitamin D, but the amount will decrease as it is stored.

Horses over 1,100 lbs are required to use Approximately 3,000 IU daily.

When your athlete might need more: If your hardworking athlete is kept indoors with little exposure to the sun, supplementation may be recommended. Vitamin D is also important for children growing up, so ensure they spend enough time outdoors in the sun.

Vitamin E
What it does: Removes harmful free radicals from the body and protects its cells. It supports the immune system, nerve function, and muscle function. Vitamin E works with selenium (a mineral), to ensure proper muscle function.

Where it came from:Fresh pasture provides the highest level of vitamin E. However, levels decrease as hay is stored over time. D-alpha tocopheral is the active form of vitamin E.

Horses over 1,100 lbs require A daily intake of 500 IU is recommended. However, the minimum level is not well-established.

He might need more: Horses without pasture turnout may need vitamin E supplementation. Horses that are hard-working, horses who eat high-fat diets, and pregnant mares might need additional vitamin E. This may help with certain neurological or muscular conditions.

[READ ABOUT: Vitamin E]

Vitamin K
What it does:Vitamin K performs many functions. It is essential for the proper functioning of blood-clotting systems in horses.

Where it came from: Vitamin K is found in hay and is made by normal bacteria in the large intestine of your horse.

Required by a 1,100-pound horse: Because horses produce sufficient amounts of vitamin C without supplementation, there are no requirements.

He might need more: A horse with severe or prolonged intestinal disease could have a reduced ability to make adequate vitamin K. Your horse may need more vitamin K if he is toxic to a substance that blocks vitaminK (such as rodent poisons or warfarin).

Mineral Guide

A basic diet of hay and pasture will provide the majority of your horse with all of its mineral requirements. Sometimes, the ratio of two minerals can be more important than the actual amount because it could influence absorption and activity. Calcium:phosphorus ratios should not exceed 1.5:1 because excessive phosphorus can have a negative impact on calcium absorption. Zinc:copper ratios should not exceed 1:3, as these minerals compete for the same transport systems in the body.

Nutritionists are also paying attention to the minerals in the ration. Inorganic minerals, or mineral salts, are less readily absorbed by horses than their organic counterparts (paired with proteins and amino acids). If you live in an area that requires selenium supplementation, it is a good idea to opt for a supplement with organic selenium over selenite (the non-organic).

Below is a guide that will inform you about the most important minerals to be included in horse’s diet.

Sodium Chloride (Salt)
What it does: Helps to maintain proper fluid balance within your horse’s body.

Where it came from: Your horse receives sodium chloride as part of his basic diet. Salt is a common ingredient in concentrate (grain) rations.

Horses over 1,100 lbs. Daily salt needs. Because daily salt requirements can vary so much, it is difficult to give specific recommendations. He needs between 1 to 6 ounces of salt daily. Is there nutritional wisdom in horses? However, he does not need salt. He will eat what is in his salt block if it’s available.

He might need more: Salt is lost through sweat. Your horse can lose up to 30g (almost one ounce) in just a few hours of hard work. It is important to ensure that your horse has enough sodium chloride in his system, especially if he works hard and in hot conditions.

[READ MORE: Horse Feeding Salt]

What it does: Essential for building bone.

Where it came from: Alfalfa Hay has high calcium levels, with Ca:Phos ratios as high as 6 to 1. While grass hays contain calcium, the ratios of Ca and Phos can be closer than 1:1, which makes grass hay somewhat calcium-deficient.

Horses over 1,100 lbs require 30g-40g per day.

When your horse might need more:Calcium plays a vital role in bone growth and development, during pregnancy and after birth. Your horse may need more calcium if he is being fed grass hay or cereal grains (such as oats) than his Ca:Phos ratio.

What it does: Combines calcium with Gives strength to bones.

Source: Most hays contain phosphorus, but it is also high in cereal grains. Brans have a high level of phosphorus.

Horses over 1,100 lbs require 18 – 29 g per day.

He might need more: Phosphorus is essential for growth and development, just like calcium. Senior horses might also be less efficient at absorbing phosphorus. Most senior feeds contain slightly more than other concentrates.

What it does. This mineral is involved in energy metabolism, muscle contraction and nerve impulses. It is also one of the most important minerals in bone.

Where it comes: Magnesium can be found in many hays and grains. For a 1,100-pound horse, it is required to consume 7.5g to 12.0g per day.

When he might require more:Magnesium can be used to calm nerves and relax muscles.

What it does Maintains the electrical balance between cell membranes. It plays an important role for muscle contractions and nerve impulses. A 1,100-pound horse will need 25g to 32g of potassium per day.

He might need more: Potassium can be lost through sweat and may require supplementation, especially when the temperature is high. Excess potassium can be a bigger problem for horses suffering from HYPP (a genetic muscle disease). It is important to limit the intake of potassium.

What it does. Helps with bone and joint development. Copper is also involved in the formation of hemoglobin. This is the molecule that transports oxygen to your horse’s bloodstream. Your horse could become anemic if it doesn’t have enough copper.

Where it comes From: Copper is found in most hays and beet pulp. Molasses, which is a good source of copper, is used in concentrate rations. Horses over 1,100 lbs require 0.1g to 0.12g daily.

He might need more: The minerals molybdenum, zinc and iron may interfer with copper metabolism. Additionally, excessive iron can cause copper absorption to be impaired. Extra copper may be recommended if these minerals are present in large amounts. Because copper is essential for proper bone and joint development, this can be particularly important for young children. Copper deficiency can lead to horse coat turning orange or sunburnt in summer.

What it does:Zinc supports a wide variety of enzymes in their respective functions. It is involved in wound healing and immunity, and may also play a role with reproductive function.

Where it came from: Most pastures, hays and grains have adequate amounts of zinc. Horses over 1,100 lbs require 0g to 0.25g of zinc per day.

He might need more: Iron, like copper, can inhibit zinc absorption. Additional zinc might be needed if your horse is being exposed to too much iron. A lack of zinc can cause horses to become orange-colored in the sun, just like copper.

What it does: This mineral is essential for many cell mechanisms. Its roles in nerve and muscle function are the most important. It is essential for the proper metabolism of vitamin A.

Where it comes From: Selenium is found in soil and horses get it from their hay. Certain areas have high levels of selenium while others are low. For a 1,100-pound horse, 3mg is required per day.

He might need more:Some soils in the United States, like the Pacific Northwest, Great Lakes and the eastern seaboard, are deficient in selenium. Additional supplementation is recommended. The range between selenium deficiency or toxicity is the narrowest of all minerals. This is why it is important to consider this mineral. A simple blood test can determine if your horse is getting enough selenium from his diet and help you to supplement it.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!