Written By Dr. Kris Hiney

 

In the last two articles we discussed evaluating your horse’s body condition and then determined how many calories your horse needs to maintain their weight. We discussed factors that will influence the horse’s “at rest” or maintenance requirements; including his condition, his personality, and the weather. This month we are going to talk about more active horses, the Working Class.

Be Realistic About Your Horse’s Workload.When we discuss how much energy, or calories, our horses’ need for work, we first need to be realistic about how much we are riding them. Just because we may be at the barn for quite a while, many overestimate the time the horse actually spends exercising. It may seem like we might ride for a good hour, but it might actually be quite less. I’ll use myself as an example. I might ride my young horses about 30 minutes per day, but I find it takes me three hours to ride just two horses! The time spent grooming them and chatting with your friends definitely can’t be counted in your horse’s workload!

Where Does Your Horse Fit?The National Research Council suggests four basic categories for work. These descriptors are light work, moderate work, heavy work, and very heavy work. First let’s discuss what these categories include, then later, what may alter these basic requirements.

Light Work.Horses in light work typically are not ridden every day. These horses may only be ridden 1-3 hours per week and usually at a slower pace. The majority of their exercise is performed at a walk or trot, with very limited time cantering. A good example of this type of horse is one that is used for light trail riding on a limited basis. For owners who have limited time availability to dedicate to their equine pursuits, they might find their horses fall into this category of work. Horses ridden at this level are typically the easiest to feed. The increase in their caloric needs is quite modest, increasing by only 20% over their “at rest” values. Horses that may only be ridden once per week or even less can really be treated the same as a maintenance horse. Riding a horse once every two weeks or so will not alter the energy needs of the horse significantly.

If you are unable to ride your horse multiple times per week, or even if you can, make sure your horse has adequate time to stretch his legs!  Horses which are stalled and not kept in a consistent riding program quickly become bored and may develop many unhealthy habits.   Horses naturally spend the better part of the day grazing and therefore moving at the same time. When we prevent these normal behaviors through confinement and don’t provide exercise, horses develop abnormal behaviors to help alleviate their frustration.  Stall walking, weaving, wood chewing and cribbing are all symptoms of a frustrated horse. So do those horses in light work a favor, and keep them outside if possible. Your horse will thank you for it.

Moderate Work.If you consider an active training schedule for most horses, we would expect to ride the horse on average five days per week. Typically, these horses are being physically conditioned for an event or are in some sort of consistent training process (even if the training is more for the rider. Expect the horse to be ridden between 3 to 5 hours per week and to do more intensive exercise. Horses will spend more time at a trot or canter, and may be performing more specific skill work. This could include jumping low fences, beginning work on barrels, dressage maneuvers, etc. Most of our performance horses which don’t engage in strenuous activity but are ridden regularly fit the category of moderate work. To meet these horses’ needs, typically the amount of calories the horse consumes would increase by 40%.

Heavy Work.The horses in heavy work will be ridden a similar number of days per week, and perhaps even for the same duration, but the intensity of the exercise has increased once again. The horse may work at a faster gait, such as a much faster canter or gallop, or their effort in work has increased. The horse’s may be jumping larger obstacles, performing longer, or running faster. Examples of horses in heavy work would include reining horses, three day eventing horses, jumpers, polo horses, or even ranch horses. One major difference between the horse at moderate work and heavy work is usually the addition of anaerobic activity. In general, if a horse is working at a level in which its heart rate is over 150 beats per minute, they are using their anaerobic energy systems. For instance, in reining horses, the fast circles, spins and stops of a trained horse will cause the heart to beat at 150 beats per minute or greater. Horses in the heavy work category will generally need an increase of 60% over their maintenance requirements.

Aerobics for Horses? 

When describing work intensity, exercise physiologists use the terms aerobic vs anaerobic work.  Technically aerobic work is at a low enough intensity that the muscles of the animal can rely on the slower metabolic pathways. You may remember learning about the TCA cycle or the Kreb’s cycle in previous schooling. That is the aerobic energy systems. Its job is to provide the energy source for muscle contraction – a little molecule called ATP. All dietary energy sources; fats, carbohydrates and protein can be utilized in aerobic metabolism.  The word aerobic means that these fuels are burned in the presence of adequate amounts of oxygen.  That means that the horse’s heart and lungs can keep up in the race to deliver oxygen to the tissues.When the horse’s muscles are contracting faster or harder than the ability of the cardiovascular system to keep pace, they then enter into anaerobic metabolism. The horse must then switch to a different supply of fuel, primarily carbohydrate metabolism.  They are simply working too hard for the aerobic system to keep up with the demands of the muscles for ATP.  Don’t worry too much about the details right now, we will spend more time with these topics in later issues.

Very Heavy work.The last category of work intensity probably has the fewest numbers of horses within it. These are our race horses, whether they are Quarter Horses, Thoroughbreds, Standardbreds, or even endurance horses. They have quite the job to do, and need the fuel to do it. While their training schedule may be a bit more varied than the previous two categories, the level at which they work raises their energy requirements to almost twice that of their energy needs at rest. Maintaining the proper caloric intake in these horses and keeping them at the proper condition can potentially mean the difference between win, place or show.For next month we will discuss other factors that might change your particular horse’s energy requirements for work. And we certainly can’t forget to mention the growing horses and the broodmares! For now, try to determine what work load your horse is in, and look up its caloric requirement below, in Table 1. Energy Requirements For Work. And remember, be honest!

Table 1. Energy Requirements For Work (Mcal/d).  

Wt of horse (lb)	Light	Moderate	Heavy	Very Heavy
900	16.1	18.7	21.4	27.7
1000	17.8	20.8	23.8	30.8
1100	19.6	22.9	26.2	33.9
1200	21.4	25.0	28.6	37.0
1300	23.2	27.0	30.9	40.0

Quick Tip!While we haven’t discussed caloric intake sources (coming soon), a great way to increase calories is to add safe fat to the diet. Fat has 2.25 x the amount of calories per lb compared to anything else we can feed our horses. Add safe fat sources made with stabilized ground flax seed (rich in Omega-3 essential fats) and/or stabilized rice bran (rich in powerful antioxidants and Omega-6 essential fats) – Omega Horseshine®, Omega Antioxidant, Omega Grande®, Omega Stabilized Rice Bran, or the horse treats that Horse Journal™ named: “Best Buy” – Omega Nibblers®. These supplements add calories quickly and safely.Watch for January’s Health-E-Letter when we will talk about EXERCISE AND ENERGY NEEDS – WHAT IF MY HORSE DOESN’T FOLLOW THE RULES? – Part 4 in my Understanding Horse Nutrition: How to Achieve Maximal Performance From Your Equine Companion series. 

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