Consumption of nutrients does not always equal absorption of nutrients. Nutrition impacts cartilage, tendons, ligaments, bone, hoof, skin, muscle and connective tissues (fascia). Collectively influencing all these parts are the horses’ endogenous enzyme systems. For example, collagen, elastin, and keratin are all structural support tissues that will critically determine how our horses respond to athletic stress.
Within each cell and support tissue, myriad enzymes are critical to health and performance. Enzymes are proteins that catalyze (accelerate) chemical reactions vital for tissue strength and elasticity. For most enzymes to work, they must have a cofactor, and often this is a trace mineral such as zinc, copper or manganese. If the equine structural support system does not have an adequate pool of these trace minerals, then enzyme activity is limited and tissue integrity can be compromised. Could we improve the equine structural support system by optimizing zinc, copper and manganese absorption? We may be able to gain insight through interesting research in food animals.
All of us strive to feed our horses high quality rations that are formulated by talented equine nutritionists using the latest research guidelines. The obvious question is, “How can horses being fed a balanced ration be deficient in trace minerals?” The simple answer is they may be marginally deficient or have a subclinical deficiency.
What is a subclinical deficiency? Our horses on balanced rations look and feel fine, but when we stress them with athletic exercise, their structural support system can’t handle the load and end result is tissue damage. When this occurs we could see a clinically lame horse with tendon, ligament or joint damage. A subclinical trace mineral deficiency is not readily apparent until we exceed the tissues’ ability to respond to stress.
Most horse feeds have more than enough copper, zinc and manganese to meet National Research Council guidelines. However, the absolute key is not how much mineral is consumed, but rather how much mineral is absorbed. The amount of mineral that is absorbed out of the intestinal tract and into the horse’s bloodstream is dependent on many factors. The form or type of trace mineral consumed can dramatically influence the amount of mineral absorbed. If a particular mineral structure is more likely to be absorbed, it is considered to be more bioavailable.
INORGANIC TRACE MINERALS
The most common form of trace minerals used in horse feeds are inorganic mineral salts such as zinc oxide or copper sulfate. These are the least expensive forms of trace minerals and least bioavailable to the animal. The vast majority of inorganic trace minerals will never be absorbed by the horse’s intestinal tract. In fact, inorganic trace mineral salts have now become an environmental concern in the food animal industry. So much of the inorganic trace minerals are passing out in the manure that the environment is being polluted.
Inorganic mineral salts in the acidic pH of the horse’s stomach will break apart. For example, when copper sulfate reaches the horse’s stomach the copper will separate from sulfate. Then in the alkaline pH of the small intestine the copper can recombine with other molecules to form un-absorbable complexes. When this happens the copper will never be absorbed by the horse. This same problem occurs with zinc and manganese inorganic salts.
Many entities in our horses’ diets can bind with inorganic minerals and render them unavailable. Phytates that are commonly found in grain are known to readily bind with inorganic minerals in the intestinal tract. Diets high in calcium salts such as alfalfa forages are also known to bind inorganic minerals. Hard water can contain calcium or sulfur salts that will render inorganic mineral unavailable. The bottom line is that a high percentage of the inorganic minerals consumed are passing out the south end of a north-bound horse.
An alternative to these poorly absorbed inorganic minerals are organic minerals. The word “organic” does not mean these minerals are produced “organically.” Organic in this context is a chemical description of the mineral structure. Simply put, a mineral is organic when it is bound to carbon-based molecules. Whatever is bound to the mineral is called the ligand. Typical ligands of organic minerals are usually amino acids, peptides or sugar molecules. Not all organic minerals are created equal. The particular ligand bound to a trace mineral will determine how bioavailable the mineral is to our horses.
Another name commonly used for an organic mineral is a chelated mineral. The word chelate is Greek for “claw.” The chemical bonds of the ligand grab onto and surround the mineral like a claw. Organic or chelated minerals are also referred to as protected minerals. Theoretically, the chemical bonds are so strong that these minerals are “protected”. In other words, an effective organic mineral will not break apart in the stomach and will not form insoluble (unavailable) complexes.
If an organic mineral is not acid resistant, it is no better than an inorganic mineral. Organic minerals that survive the stomach will be able to present the mineral to the intestinal cells for absorption. In fact it is now possible to measure organic trace mineral absorption through accurate RNA based assays.
I have been a champion of organic minerals in equine nutrition for many years. The logic behind organic minerals seemed sound so I have been an advocate. I assumed that most organic minerals were of similar value and just variations on the theme. It is now clear to me that the value of organic minerals is totally dependent on the ligand bond and whether this bond is resistant to stomach acid degradation.
I became attracted to organic minerals because of food animal research that has shown profound clinical benefits. However, to date there have been few equine-specific organic mineral studies. Plenty of anecdotal evidence supports the use of organic minerals in horses, and research is underway to validate their use in a holistic nutritional approach toward total structural support.
Food animal research may not initially appear to be of any value to your horses. However, if we are to gain new perspectives in equine nutrition, we should at least critically consider research in all species. The basic scientific principles are often applicable across species. In addition, the types of studies done in food animals with organic minerals may never be duplicated in horses for humane and ethical reasons. If we dismiss all food animal research, we may miss out on exciting nutritional possibilities for our horses. I fully support and seek equine specific research, but I can’t ignore what talented scientists have proven with organic minerals in food animals.
Proven food animal benefits with one acid resistant class of organic minerals include:
- Increased bone mineral concentrations
- Increased bone breaking strength
- Less tendon and ligament pathology
- Less cartilage pathology
- Fewer foot lesions
- Less synovitis (inflammation of joint capsule)
These results have not been found with all organic minerals. I suspect that the above benefits will be repeatable only with organic minerals that can survive the acid of the stomach. If we are to utilize organic minerals in horses it seems logical to start with minerals that have proven acid resistance.
For all the potential advantages, I believe we need to consider high quality organic minerals that are scientifically validated. Even if your current ration includes organic minerals, not all organic minerals are created equal and most of the minerals in your horse feed will be inorganic. Especially if your horse is under an athletic stress, it may be beneficial to supplement additional high quality organic trace minerals to optimize the entire structural support system.
As we move forward in equine nutrition we should consider how we can support total structural health. Multiple cells and tissues are involved and a holistic approach to supplying nutrients should be considered. Cellular enzymes are critical to the production, maintenance and repair of tendons, ligaments, cartilage, bone and hoof tissues. The amount of copper, zinc and manganese available will determine optimal enzyme activity. Most trace minerals in horse feeds are inorganic and poorly absorbed. Organic trace minerals are more bioavailable and supplementation with certain forms has been shown to have significant biological benefits in food animals. We need more equine specific research, but the use of effective organic trace minerals could be part of a holistic approach to total structural health in horses.
Kenneth J. Kopp DVM, is Technical Support Veterinarian at Arenus