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by Rachel Mottet, PhD and Kasia Miedzinska, PhD

Equine obesity – the problem and some solutions 

The world of equine nutrition has made great progress over the past 50 years. Horses now eat fully fortified diets – with tested, safe, quality ingredients – that optimally promote growth, performance and health status.

Many horse owners are actively involved in nutrition decisions and understand that the healthiest diet for horses is one that promotes an abundance of fiber, ideally from pasture or hay. 

While most owners recognize that fairly continuous forage consumption is the best way to keep the horse’s gastrointestinal tract healthy, we are unfortunately witnessing a hugely prevalent issue – equine obesity – which is exacerbated by this model of feeding. 

How did this come to be?

One way is when ‘easy keepers’ or obese horses are fed an all-you-can-eat forage diet. You read that right – some horses can become obese from simply eating too much hay. That probably seems odd since the horse has evolved as a species that spends 14-16 hours per day grazing. Yet equine obesity is extremely prevalent, and our high-quality forage and feed abundance model is a big contributor. 

It’s important not to blame equine obesity on nutrition alone – other factors are at play, including overfeeding energy-dense and high-fat feeds, lack of exercise, show ring expectations of a ‘full’ appearance, a genetic predisposition or thrifty genotype, and numerous other factors. 

But since nutrition is a key factor in obesity, an abundance of caution should be taken when establishing a horse’s nutrition program. Mismanagement can lead to insulin dysregulation and founder, both of which can greatly impact the horse’s quality of life, comfort and longevity. 

Slow-feeder systems

It is important to establish a forage intake program that suits each specific horse. As advocates of ad-libitum (all-you-can-eat) forage, we must determine which is the lesser of two evils: restricting access to hay or potential, significant metabolic consequences. We need to select a feeding system that promotes a natural equine diet, while preventing the horse from becoming obese.

Slow feeder systems have made an enormous difference in the overall health of horses. They mimic the natural, slow, fiber-intake model that is best suited for horses and allows owners to control the amount of hay consumed. (It should be said that not every horse requires monitored hay intake.) 

It is important to note that forage intake should not be less than 1.5% of the horse’s body weight. If this hay is provided in a good slow-feeder system, the horse will spend much of their day eating that amount. This promotes a healthy gastrointestinal tract and allows the horse to more readily maintain ideal condition. 

The circumstances under which horses are fed vary widely across North America, ranging from stall-bound to individual short-term turnout to small group partial turnout (6-12 hours), to living 24/7 in a herd. Slow feeders are available for all these circumstances. It is interesting to note that consistent (even if metered) availability of forage has been observed to alter herd dynamics. 

Ration balancers

Another major development over the past 25 years is the formulation of ration balancers – a wide range are available on the market.  

Ration balancers were initially developed to compensate for lower than intended feeding rates of complete feeds. Such lower feeding rates were necessary when the recommended amount provided too high a level of carbohydrates and fats for a specific horse. 

Ration balancers have evolved to the point where some of them are so highly concentrated and fortified that they are used as a base feed, with additional carbohydrates and fats being added, as required, to meet performance needs.

What is interesting – and not immediately apparent – is that this development has engendered a complete pivot in our approach to feeding. The older, traditional approach judged the success of a nutrition program based only on the horse’s body condition (predating the body condition scores with which we are now familiar) and performance – there was an assumption that good body condition was a consequence of health. Today’s approach focuses on health first by nourishing the specific body systems, then tops things off by addressing body condition and energy level. 

This approach also reduces the number of supplements required, preventing the over-feeding of supplements which comes with its own issues, too numerous to list here. 

What does this have to do with equine obesity?

It is a fallacy to believe that one must starve a horse in order to achieve weight loss. The weight loss process is an enormous stress on the body, affecting multiple systems. 

It is, in fact, preferable to ‘feed a horse into weight loss’. While working on weight loss, it is necessary to support all the systems – musculoskeletal, respiratory, cardiovascular, endocrine, reproductive, etc. – throughout the process. 

In the absence of a natural lifestyle involving 15-20 miles (~25-30 km) of movement a day, ration balancers are a gift to the owner of the obese horse, as they avoid unnecessary carbohydrates and fats while allowing optimization of health throughout the weight-loss process. 

Many formulas are available – it is simply a matter of finding the one suitable to the specific circumstances.

In closing…

The explosion in knowledge from research published over the past 30 years has been extraordinary. And the sharing of information around the world has been a model of cooperation. Indeed, keeping up with the rapidly changing landscape of feeding theories can be a real challenge. 

We need to remember that horse management over the past millennia was not all wrong – were that the case, horses as a species would not have survived domesticity. 

It is important to temper our eagerness to jump on every new nutrition concept with the patience to field test research results, and always remember that horses were designed for a particular lifestyle. Proof lies in taking a close look at the extraordinary body condition maintained by most horses living in the wild in seemingly sparse environments. 

It is unfortunate that we are no longer able to keep horses in those optimal conditions due to loss of available land, but we do our best to mimic some of those conditions by continuing to do research and by expanding cooperation within the feed and agricultural industries and with veterinarians.