Understanding Horse Nutrition, Part 1: Too Fat, Too Thin, or Just Right

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 Written By Dr. Kris Hiney
Horse nutrition can be a complex issue. We can feed horses to maximize stamina and power, prevent digestive disorders, avoid metabolic disorders, prevent attacks caused by genetic diseases, grow horses to be sound throughout life — the list goes on and on. Trying to wrap one’s mind around all of these issues can be intimidating at best, even for equine nutritionists, let alone the average horse owner. However, we will begin with the basics, and then build to more complicated ideas.

This month we begin our series on Understanding Horse Nutrition: How to Achieve Maximal Performance, with Part 1 — TOO FAT, TOO THIN, OR JUST RIGHT? We will be discussing the proper weight or condition for your horse depending on its career. We will then put together these ideas to determine the amount of energy we should be providing to our horses. We will conclude our energy talk with the most optimal way to provide energy to your horse to gain that competitive edge. In future months, we will discuss common horse diseases and disorders that are impacted by our feeding strategies.

One of the easiest nutrients to be fed to horses is not a nutrient at all – but energy. Ironically, energy is often the most commonly misunderstood. When horse nutritionists talk about energy, we simply mean calories. Energy to your horse can be supplied in many ways, from carbohydrates, fats or proteins. All of these can be utilized for your horse for fuel.However, when many horse owners refer to energy, what they really mean is how their horse feels. Does he seem lethargic, or does he come bouncing out of his stall or paddock? While how the horse feels can be impacted by how many calories it receives, there are many other factors that contribute to the overall health or attitude of the horse. But certainly improper management of the calories the horse is receiving can alter your horse’s demeanor.The idea seems simple enough, we feed horses enough so they are neither fat or skinny, right? Pretty much, but of course there has to be a little bit more to it. Exercising horses need more energy, sedentary horses need less. Some types of horses need more feed to put on weight, while the “easy keepers” could exist on air. We all know this, just from our own life experiences. So why do so many horse owner’s struggle with achieving that perfect weight in their horses? Is there a perfect weight? What’s good for one type of horse may not be good for others.

Body Condition Scoring – from 1 to 9.To better define the energy needs of horses we will look at the idea of body condition scoring in horses. The body condition scoring system for horses is a numerical system used to assign a number to describe the fatness of a horse, or how much energy he has stored on his body. The system that is most often used today was created in the 80’s at Texas A&M University. Horses are assigned a number from 1 to 9, with 1 being extremely thin and 9 obese. This system of assigning numbers with the degree of fatness allows veterinarians, equine nutritionists, barn managers and trainers a common language to describe the best condition for horses to be for their optimal performance. The system is even used in court to prove cases of animal neglect and abuse. You may be familiar with similar types of systems, as they are frequently used in other livestock, and even with our in-house companions, cats and dogs.
Fat – seeing and feeling.

In horses, we examine eight parts of the animal’s body, both visually and manually, to come up with an overall body condition score (See Figure 1). The six main areas to examine are over the crest of the horse’s neck, their withers, behind their shoulder, over their ribs, the crease on their back, and their tailhead. Examining all areas of the horses’ body gives us the best idea of the condition of the animal, by taking the average value. Just like in people, some horses carry fat preferentially in different parts of their body. Sometimes where the fat is located can be an important indicator of potential metabolic problems (more on that in upcoming months!). Taking all parts of the horse into consideration is key in determining the condition score of the horse.

A horse that is average in their amount of fat is given a value of 5. If your horse scores a 5, his back should be level, you can’t see his ribs, but you can easily feel them; the withers appear rounded over the spinous process, and his shoulders and neck blend smoothly together. A horse with a score of 4 has a negative crease down it’s back (essentially the upper portion of the vertebrae are not surrounded by fat and stick up), and the ribs are faintly seen. In these horses, the withers, shoulders and neck are not obviously thin. As we go lower in body condition score, the horses appear more and more emaciated. On the opposite side, horses that are above a five begin to have a crease down their back, the ribs begin to be harder to feel, and fat gets deposited along the withers, the sides of the neck and behind the shoulder. As horses increase in fatness, the crease down the back gets deeper, fat develops up and around the tailhead, and the horse essentially loses some of the contours of its body as fat fills in.

So what body condition should you shoot for?It depends. For most exercising horses and healthy, mature horses, a score of 5 to 5 ½ is ideal. These horses will have sufficient energy reserves for work but not be impaired by excessive weight. Condition scores above 6 are generally not recommended due to the extra stress upon the bones and joints of the horse. Excess fat can also impair a horse’s ability to dissipate heat. Therefore, in horses that undergo longer periods of exercise (think three-day eventing horses, endurance horses etc.) and need a greater ability to thermoregulate, the most successful athletes range between a 4 and a 5.
Aim a little higher for breeding horses.We encourage mare owners to allow the girls to enter the breeding season at a score of 6 or 7. Mares at a score of less than five have more reproductive challenges, with delayed time of their first successful heat cycle, needing more cycles to conceive and a reduction in pregnancy rates. The boys are also encouraged to enter the breeding season at a healthy weight, as the stress of breeding season in a heavily booked stallion can cause him to lose weight.
Prepare older horses with sufficient weight for the season.

If possible, owners of older horses are also encouraged to allow them to gain additional weight prior to winter. If older horses are housed outside without adequate shelter, the energy needed to keep themselves warm may cause a drastic loss in weight. By preparing them for the season with sufficient weight, these horses have more insulation, more energy reserves, and can go through the winter season more easily.

“Hands on” time with your horse!So go out and take a look at your horses and try to give them a score. But don’t forget to get your hands on them, if you really want to know the answer!


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