Horse Feeding Myths and Misconceptions
Sorting Through the Quagmire of Misinformation
By Shelagh Niblock, PAS
How many of us remember the days when the only way to find out the facts on a subject was to go to the library and look it up? Answers to questions we had about the care or feeding of our horses might have been found in one of the many reference books we all owned. Or, maybe we would find the information we were looking for by perusing the many equine magazines we kept “just in case.”
Now, all of us with a cell phone or a home computer have the information at our fingertips. The answers to our questions about the “best practices” for the care and feeding of our horses are as easy to find as a telephone number. This must be a good news story… right? No, not always.
Since the inception of the internet and in particular, social media sites like Facebook, myths and misconceptions about many aspects of horse husbandry have proliferated. Nutrition and feeding practices for horses have been a particularly fertile field for the development of myth, misconception, and sometimes absolute propaganda.
There are many myths and misconceptions to be found online, and some of them prey on our insecurities about the care we provide for our horses. Nutrition and feeding have been particularly prolific areas of misinformation. Photo: Shutterstock/Wavebreakmedia
Are Facebook and other internet sites reliable?
Facebook has literally thousands of interactive groups where members are invited to share their equine experiences and ask questions of the moderators and/or other members. Other internet sites are set up strictly for dispensing information. The objective of some sites is pure marketing of a product or service. Some websites are good at preying on our insecurities about the care we provide for our horses. Unfortunately, there is rarely any demand for accountability when posting on the internet. Often, information is promoted as fact, and although it may have a nugget of truth at its foundation, it is aimed purely at marketing.
The hay we feed our horses also provides an internet platform for plenty of discussion and often, for misinformation and half-truths. These sites frequently generate more questions than they provide answers for average horse owners. One such subject is the use of GMO (genetically modified organism) forages and glyphosate (Roundup®) on the forages we feed our horses. While there may be rationale for a debate about whether we should be using GMO crops or glyphosate on forages and other feeds, the truth is that they are used, but not widely, and only under certain circumstances.
Is the hay I buy a GMO hay?
There are no approved varieties of GMO cool season forages commercially available anywhere in the world. This includes forage varieties such as orchard grass, timothy, rye grass, brome, and tall fescue. Consequently, all grass hay is “non GMO.”
Roundup Ready® Alfalfa (a GMO variety), however, has been approved for use in both the United States and Canada, although it’s very unlikely you would ever find it in a mixed stand of forage containing both grass and alfalfa. Roundup Ready® Alfalfa cannot be sprayed with glyphosate (the herbicide RoundUp®) in a mixed stand because while the alfalfa will survive the herbicide application, the non-GMO grass will not. Horse owners buying grass hay or alfalfa-grass hay mixes will find that they are always non-GMO and will never have been sprayed with the herbicide glyphosate.
All grass hay is non-GMO, but Roundup Ready® Alfalfa may have had an application of glyphosate applied. Alfalfa-grass hay mixes are always non-GMO because although the alfalfa will survive the herbicide application, the non-GMO grass will not. Photo: Shutterstock/B Brown
On the other hand, pure stands of alfalfa hay may be GMO (Roundup Ready®) and if so, may have had an application of glyphosate applied early in the life of the forage stand. The herbicide is not typically reapplied every year, although it could be applied to a mature stand to clean up a bad weed infestation. The amount of residual glyphosate on a Roundup Ready® crop of hay is reported to be low, and although research in ruminants has suggested it is safe, the research has not been done to determine the impact, if any, in the digestive tract of the horse.
Was my hay sprayed with Roundup® prior to harvest?
The use of glyphosate has increased significantly in commercial agriculture over the last 25 years. One approved use for glyphosate is as a pre-harvest desiccant. In this circumstance, glyphosate is applied to a mature crop to “dry it down” and bring the crop to a consistent moisture level in order to facilitate harvest. An application of glyphosate to assist in the dry down of a crop of grass or grass alfalfa mix hay will never happen because it will kill the stand of forage, resulting in a need to reseed the field. Reseeding a field is a costly and time-consuming exercise that commercial hay growers do not want to have do any more often than about every five years. The use of glyphosate on forages will only happen on stands of Roundup Ready® alfalfa, and even then, usually only in the establishment of the stand.
Is it safe to feed hay treated with propionic acid?
Propionic acid is a short-chain fatty acid that is produced naturally in the hindgut of your horse. Growers will sometimes spray cut forage with propionic acid before baling if the moisture in the forage is high. The propionic acid preserves the hay and prevents the growth of mold and other fungi.
While propionic acid-treated hay is safe for horses, the use of it by the grower does suggest that the hay was baled at a higher moisture content, increasing the risk of inconsistent quality. Propionic acid treatment of hay is very expensive and growers will only utilize this preservative as a last resort when harvesting under difficult conditions.
Before baling, hay growers sometimes spray cut forage with propionic acid if moisture content is too high, to preserve the hay and prevent the growth of mold and other fungi. Photo: Canstock/Aorlemann
Some internet sites have promoted the misconception that the propionic acid sprayed onto hay as a preservative will significantly increase the sugar content of the hay. This assumption just does not make sense if you do the math. It is true that the healthy microbes in the hindgut manufacture volatile fatty acids (VFA) including propionic acid, and they are converted to glucose for energy in the liver of your horse. It is also true that the small amount of propionic acid used to treat hay at harvest could contribute to the energy status of your horse, but only if it is absorbed into the blood stream intact. Even if this was the case, it would not be a significant source of glucose precursor in the diet of your horse.
The typical application rate on small square bales is one-half to one percent of the actual acid on the hay. If your 500-kilogram horse is consuming two percent of his body weight in hay daily, he will be consuming 10 kilograms of hay. An application of one percent propionic acid to that hay will result in 100 grams (1.0% x 10 kg) of propionic acid or potential “glucose precursor” per day.
This equates to the amount of non-structural carbohydrate (NSC) that would be found in one kilogram of grass hay at 10 percent NSC.
When consumed over the course of the day, it is highly unlikely that this amount of additional propionic acid will have a significant impact in insulin or energy metabolism, even if it was absorbed intact from the gastrointestinal tract. It hasn’t been well established in the research literature exactly where in the equine digestive tract this small amount of propionic acid is metabolized, but it isn’t a big contributor to the energy status of your horse.
Some horses will never learn to self-limit their intake if given unlimited access to forage. If they are already overweight or have a metabolic condition, overeating could put them at great risk of health complications. For these horses, use a weigh scale and hay nets or a slow feeder to calculate and manage their forage intake.
How do I “fix” a loss of topline in my horse?
Another issue easily found on social media discussion pages relates to the restoration of a horse’s topline. Loss of topline refers to a loss of muscle tone and condition over the top of a horse from the point of the withers over the loins, to the croup area. Loss of topline is not necessarily indicative of poor health, neglect, or nutritional deficiency. This condition can be found in senior horses, PPID (Pituitary Pars Intermedia Deficiency) horses, horses who are sedentary, or horses who are thin. It is possible to improve the topline of some horses through exercise and feeding, but correcting it in seniors and PPID horses can be a challenge.
There are no supplements that can cure the loss of topline of any horse. Attention to protein intake and quality is one of the most important considerations in addressing poor topline in a horse. Targeting specific limiting amino acids in combination with exercise that encourages the horse to use its body more effectively also helps. Forage quality and intake are also significant contributors to improving topline. There are no quick fixes for loss of topline, but one of the most effective ways to improve the topline is to ensure your horse is consuming good quality forage.
Will horses “self-limit” when fed free choice forage?
Most horses, if offered free choice forage, will “pig out” on it at least to start with, often consuming far more in 24 hours than they require to meet nutritional needs. Some horses, when offered free choice forage on a daily basis, will self-limit their intake themselves over time, but many never will. If they are already overweight or have a metabolic condition like insulin resistance, equine metabolic syndrome or PPID (pituitary pars intermedia dysfunction, or Cushing’s disease), they will be at great risk of health complications due to excessive energy intake if allowed to overeat.
There are internet sites where a slavish devotion to allowing your horse unlimited access to forage is recommended. The suggestion is that all horses will learn to self-limit their feed intake. Please be very cautious about following this kind of advice. You know your horse the best, and if you are worried that your much beloved “Mr Chubbles” will never learn to self-limit his feed intake, remember that you are the best judge of that. Keeping feed in front of horses all day is good for their physical and mental well-being, but for those horses who will never learn to self-limit their intake, safe hay intake is best accomplished through the judicious use of a weigh scale and hay nets or a slow feeder.
Why is math important?
Opinions abound on the internet about the “safe” intake of some nutrients for your horse. Nutrients such as starch, sugar, NSC, and iron are particularly subject to much discussion. It’s a great idea to have a good handle on how much of these nutrients your horse consumes, but remember a few simple guidelines when calculating nutrient intake totals.
There are no quick fixes for improving the horse’s topline, although opinions on this topic abound on social media discussion pages. Look for unbiased information supported by good research, and if you have any doubts, consult a professional with expertise on the subject. Photo: iStock/Wavebreakmedia
First of all, horses eat nutrient weights, not percentages. A feed with what appears to have a high NSC percentage may not be contributing a significant amount of starch or sugar to your horse’s diet due to the low feeding rate. For example, a pelleted mineral supplement that has an NSC of 40 percent may sound shockingly high, but if you only feed 250 grams daily, you are actually only delivering 100 grams of starch and sugar combined. Again, that’s equivalent to the NSC contributed to your horse’s diet by one kilogram of low sugar, 10 percent NSC hay. If you are worried about precipitating a glucose/insulin response by feeding the mineral, divide the daily intake into two or more small meals a day, thus reducing the NSC per meal and minimizing any potential metabolic impact.
Iron can also cause confusion. The tag on any mineral supplement will report the amount of iron (either total iron or as added iron) in milligrams/kilogram (mg/kg, also known as PPM or parts per million) of product. Rarely, though, will the recommended daily intake of the mineral be as high as 1,000 grams or one kilogram. For example, a mineral that has total iron reported as 1,000 mg/kg, with a suggested intake of 250 grams per day, will be delivering 250 grams of iron. Make sure you do the math in assessing the products you may want to feed, or not feed, to your horse.
How do I find accurate information?
Good peer-reviewed research is still the best way to get facts about the well-being of our horses. Look for writers, research groups, and publications that have a reputation for providing unbiased information that is supported by good research. Utilize search engines like Google Scholar that deliver links to scientific papers.
Beware of special interest groups or organizations marketing a product or a philosophy not backed up by solid research. Purveyors of online information who won’t allow you to question them or critique their findings may have something to hide. Be discerning about whether the website is offering an opinion masquerading as a fact. Websites offering vague references to clinical trials but no citations or references to back up their claims should be considered suspect. Don’t be afraid to question or be skeptical about something. The foundation of good science is the recognition that whatever the outcome of research, critical questions will be asked, and welcomed.
Another important tip: If you have doubts, remember to ask a professional with expertise in the subject. And most importantly, if it sounds too good to be true, it probably is.
This article was originally published in the Early Summer 2019 issue of Canadian Horse Journal.
Main article photo: Shutterstock/Monster Ztudio