Preservatives in Feed and Supplements

I have been asked many times about preservatives in horse feed and supplements. Frankly, I didn’t know very much about preservatives because BioStar never uses them, so I decided to hop down into the rabbit hole and find out.

Ethoxyquin was developed over 35 years ago as a rubber stabilizer by Monsanto. Approved as a both a fungicide and a preservative, ethoxyquin is used in feeds to protect fats from rancidity (lipid peroxidation). The foundation of ethoxyquin is quinoline, which is made from coal tar (just like the B-vitamins found in pet supplements, human supplements, and equine supplements). Quinoline is also the foundation for an herbicide called Assert (Canadian trade name: Spike-Up) and used as a growth regulator to protect apples and pears in harvest and storage.

Propionic acid is formed synthetically from ethyl alcohol and carbon monoxide. It is classified by the EPA as a fungicide and bactericide. BASF is the world’s largest manufacturer of propionic acid, producing 149,000 metric tons in 2010. Propionic acid is a component in apple cider vinegar (along with lactic, citric, and acetic acids) and is also a chemical component of human sweat. Propionic acid, as it is used in feeds and hay, is not from apple cider vinegar; it is the synthetic form. The New Jersey Department of Health has a Hazardous Substance Fact Sheet on propionic acid, and the greatest dangers seems to be to the humans using it to spray crops. It is listed as a carcinogen. However, I could find no data at all about the dangers of propionic acid to horses. As propionic acid is used in various parts of the country on hay, it appears to be relatively safe for equine ingestion.

Citric acid is a component of citrus fruits, but this preservative is not extracted from lemons, oranges, and limes; it is made through a fermentation process of corn-steep liquor, molasses, and hydrolyzed corn starch. At the end of the fermentation process, citric acid is isolated by precipitating it with calcium hydroxide to yield calcium citrate salt that is then regenerated with sulfuric acid. The corn by-products used (corn-steep liquor, and hydrolyzed corn starch) are from genetically modified corn. In 2007, worldwide production of citric acid stood at 1,600,000 tons with China the largest single-country producer, manufacturing over 50% of that total. Archer Daniels Midland (ADM) is the largest producer in the US.

Further down the rabbit hole: People who are sensitive to MSG (monosodium glutamate) may not be aware that during citric acid processing, not all the corn protein is removed, resulting in hydrolyzed protein which then yields free glutamic acid (essentially MSG). Individuals with MSG sensitivities need to be aware that textured protein, soy protein, soy protein concentrate, soy protein isolate, whey protein, whey protein concentrate, whey protein isolate, and citric acid always contain processed free glutamic acid.

Natural vitamin E is known as semi-synthetic vitamin E (d-alpha tocopherol). The oil form is sourced from soy, palm or vegetable oils, and then esterified using acetate. Acetate is made from acetic acid that can be produced by bacterial fermentation (for use in apple cider vinegar and called virgin acetic acid) but is predominately made by methanol carbonylation. This method, developed by Monsanto, uses methanol and carbon monoxide to produce acetic acid. Methanol is derived mostly from natural gas, although it used to be commonly produced from coal. The basic esterification process is a chemical reaction in which two reactants (commonly an alcohol and an acid) form an ester. Though generally not used as a preservative, synthetic vitamin E (dl-alpha tocopherol or dl-alpha tocopheryl) is used by some companies in the feed and supplement industry for vitamin E supplementation.

Oils sourced for natural vitamin E: Keep in mind that the principle oils extracted for their vitamin E content (corn, soy, palm) are extracted using hexane; corn and soy oils are from genetically modified seeds unless stated organic. Palm oil, which is becoming a worldwide source of edible oil and biofuel, has recently come under severe criticism as the deforestation of Indonesia (the largest producer of palm oil) goes unchecked.  The region in question includes rainforests (Borneo, Sumatra) as well as habitats for several endangered species including orangutans, Sumatran tigers, clouded leopards, and Sumatran elephants. It is estimated that 1.87 million hectares are cleared each year in Indonesia for palm plantations.

Remember: Natural vitamin E is not the same as food-sourced vitamin E. Food sourced vitamin E is the whole food itself: wheat germ, wheat germ oil, sunflower seeds, almonds, and camelina oil, etc. provide the family of tocopherols including alpha, beta, delta and gamma tocopherols. Plus horses get the benefits of the whole food itself including the co-factors.

Acetic acid is commonly used as a preservative in hay. Seventy-five percent of the acetic acid is produced by carbonylation using methanol and carbon monoxide. Acetic acid is one of the main components of vinegar, but this biological source accounts for only 10% of world production. There is no known evidence of toxicity in horses eating hay with acetic acid.

BHA and BHT: These food preservatives are banned in England, Japan, Canada, Australia and 160 other countries around the world. The National Institutes of Health’s National Toxicology Program concluded that: “BHA can be reasonably anticipated to be a human carcinogen.” The European Commission has placed BHA as a Category 1 potential endocrine disruptor based on evidence that it interferes with hormone function in at least one living organism.

Some studies suggest that BHT also acts as a weak endocrine disruptor and may impact lungs, liver, kidney and thyroid. Some data have shown that it does cause cancer in rats as well as developmental effects and thyroid changes.

Reading Labels and ingredients listings is as important, if not more important, than reading guaranteed analysis. Whether or not one wants to use a supplement or feed with preservatives, additives, or flavorings is a very personal choice. Product marketing is a powerful influence…and I know of no equine feed or supplement company that proudly promotes the fact that their products contain preservatives, additives, and flavorings. My personal rule of thumb is: if a full disclosure of ingredients is not on the website, don’t purchase the product.

Ultimately, we don’t know what the cumulative effects on horses are when feeding a combination of hay, feed and supplements that all have preservatives, additives, and/or flavorings in them. Fortunately with whole foods like alfalfa and timothy pellets/cubes, coconut meal, flax seeds, chia seeds, whole oats, rice bran we don’t have to be concerned with preservatives, additives or flavorings since these food components don’t contain them.

BioStar supplements do not, and will not, contain any preservatives, additives or flavorings.