Equine Nutrition: It’s De Plane

Posted By Dr. Jeannie Thomason on Oct 23, 2014 |

By Dr. Sarah Reagan
Instructor & Advisory Board Member at The American Council of Animal Naturopathy

(Please note that the following discussion applies to healthy horses, not sick/debilitated ones.)

Those of you too young to remember the TV show, Fantasy Island, may get a little lost by the article title; if so Wikipedia can explain it thoroughly.  🙂  The idea for this piece came to me after reading a post on Wild Horse Education concerning body scoring on wild horses and the natural fluctuations they go through. Sometimes it seems our domestic horses live on a “fantasy island” when our husbandry methods go contrary to their biological nature.

Body scoring on a horse was developed by Dr. Henneke et al. in the early 1980’s, as an attempt to standardize the assessment of body condition without mechanical means, using visual observation as well as palpation. Its use is primarily with horses in domestic situations but can be used to assess wild horses – IF the naturally occurring variations are taken into consideration. And therein lies the crux of the situation…we humans have a tendency to think we have “saved” the horse from the vicissitudes of the wild by giving him a warm bed and regular meals.

According to Wikipedia:

The Henneke horse body condition scoring system is a numerical scale used to evaluate the amount of fat on a horse’s body. It was developed by Henneke et al. (1983) at Texas A&M University with the goal of creating a universal scale to assess horses’ bodyweight. It is a standardized system that can be used across all breeds without specialized equipment; condition is assessed visually and by palpation. Scores range from 1 to 9 with one being poor and nine being extremely fat; the ideal range for most horses is from 4 to 6. … The system is based on both visual appraisal and palpable fat cover of the six major points of the horse. The system is used by law enforcement agencies as an objective method of scoring a horse’s body condition in horse cruelty cases. [In practice it is also used in clinical applications and by owners.]

Hennecke fat depositsThis is a pictorial guide to the various places on a horse’s body that will accumulate or lose fat. This particular horse is what has been determined to be about “ideal” (body score of 6) regarding weight and fat deposition. Obviously breed confirmation can have some effect on this

An excerpt from the book Equine Nutrition: From a Species Appropriate Perspective (p112), and is the book used in the ACAN Equine Nutrition course:

A little recognized aspect of the nutritional ecology of the horse is that they have evolved to be able to adapt to varying planes of nutrition. What is a “plane of nutrition”? A plane of nutrition is defined as the quantity and quality of per capita food intake. In practical terms, this means that the horse is perfectly adapted biologically to seasonal fluctuations in nutrient availability. This does not translate into – “it is ok to feed my horse only one or two large meals per day”. What it means is that the horse instinctively knows he is supposed to increase his nutrient intake – and thus likely his fat deposits – prior to winter. When you see your horse put on a little weight in the fall, this is no particular cause for alarm. By the same token, when you see your horse lose some amount of weight over winter, this again is not necessarily cause for alarm. To contradict this natural biological process can have consequences that I think are not being given proper recognition. When we disrupt these innate biological processes, we can begin to step into at least the realm of metabolic imbalance if not outright disease condition. There has been much written about the biology of behavior, but too little about the behavior of biology as science has tended to take a Newtonian view that biological processes are “mechanized”.

Allowing the horse to actually lose weight over winter respects his natural biological processes. Western civilization tends to be obsessed with diet, and overeating is an all too common occurrence. This unfortunately carries over to the animals under our care; horse owners tend to panic when they see their horse losing some amount of weight over winter and will increase the quantity of feed to compensate. This is foreign to the horse whose not-so-distance ancestors were completely adapted to a decreasing plane of nutrition over winter. Those same horses also knew to increase their plane of nutrition prior to the onset of winter and would naturally gain weight during that time. Modern day horse owners will then respond to this with either increased exercise (to get that weight off!) and/or reduction in amount of food. All of this has the effect of being virtually the opposite of what the horse would naturally do left to his own devices.

There are now many factors involved in the current management situation of the wild horses in the western US states that have dire effects upon what would otherwise be a normal situation; in other words, we no longer have “normal” regarding wild horses in many of the areas. That being said (and the discussion of which is much too involved to get into here), we can still glean some amount of information as to appropriate biological responses in horses. The remainder of this discussion referring to wild horses will “pretend” they still live in such a biologically appropriate manner.

In the wild a horse may show a body score of 4 as summer is coming on; gain weight during the warm months and going into winter, increasing to a 5 or 6; then drop to a body score of 3+ as winter ends; this cycle gets repeated year after year. In addition to seasonal changes to the food supply, we also find that the reproductive cycle plays a significant role in determining response to varying nutrition planes, with both mares and stallions being affected. The physiological response on the mare is of course due to the requirements of the foal both in-utero (we should see weight gain in the mare especially during the last trimester and reasonable weight loss after birth) and post-foaling (nursing); the physiological response of stallions is typically seen in weight loss in response to the dynamic tension that naturally exists in competing for mares.

In domestic situations, most people strive to keep their horse equivalent to a body score of 6 or a little above continuously, although we may find many people think that a body score of 6 is too “thin”. Even though there is an abundant amount of information available showing that horses evolved physiologically to be trickle feeders (i.e. requiring little bits of food over most of a 24 hour period) for some inexplicable reason many (if not most) horses are subjected to scheduled feedings two or three times per day, year around. In fact, many times their feed is actually increased during late winter months to compensate for what would be natural weight loss. These practices tend to be generated by both the human centric “use” of horses as well as an anthropocentric projection of what the equine body condition should be.

On the other hand on some of the more prominent breeding farms, we can find the concept of variable planes of nutrition being used to force mares to come into cycle earlier in the year so that, again, human needs can be met regarding production and timing of foals to either get the breeding mare back into breeding status or other work. (Artificial lighting is a co-factor in this application, meaning the mare is kept stall-bound at least part of the day under lights in order to trigger the estrous cycle earlier; and of course hard feed is generally used to effect the rising plane.) In essence, there seems to be a generalized attitude (even if not consciously) among all classes of horse owners that the “domestic” horse has adapted to a nutritional cycle that is distinctly different than their wild cousins. Nothing could be further from the truth. (In fact I could debate the idea that horses have ever been truly “domesticated” according to definition…but will save that for another article.)


Unfortunately the word “natural” has become extremely adulterated when it comes to horses. As an equine health coach, you can help teach your clients what a “true natural” lifestyle is for their horse. The courses at ACAN can help you help your clients – we invite you to join us on an exciting learning journey!

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