Colic is a word that evokes worry in all horse owners. Even in a mild case of colic, there often is concern over the horse’s health and recovery. While there are many factors that can result in digestive upsets and colic, feed management or lack thereof is a major contributor. Proper feeding is something every owner can learn and make it a part of their everyday routine.

Understanding the basics of the evolution of the horse’s digestive system is paramount in understanding how feed management impacts gastrointestinal health. Since this article deals with the basics, it may be helpful to outline the digestive tract and how each part functions. The mouth is not only the entrance to the digestive system, it also has two very important functions: to chew and produce saliva. Chewing initiates the breakdown of feedstuffs, so attention to proper dental care is essential. Saliva lubricates the feed to help in swallowing, and also contains buffers which are important in buffering stomach acid. The esophagus connects the mouth to the stomach. Because the horse evolved as a free roaming animal that grazed continuously, the stomach is very small relative to their body size. With domestication and today’s management, many horses are maintained in small paddocks or stalls and fed 2-3 times per day with a diet that often contains a high proportion of grains. Feeding smaller meals, 4 or more, more often is one method to mimic grazing and may reduce digestive upset. Providing forage encourages more chewing, stimulating more salivary production, buffering of the acid produced in the stomach and better digesta flow through the digestive system. Digesta flows out of the stomach and into the small intestine, a long tube-like structure where most of the enzymatic digestion takes place and much of the absorption of most nutrients occurs. Next in line are the large intestine and cecum, comprising the last part of the digestive tract. Here, bacteria and protozoa digest fiber from plants and furnish much of the energy the horse consumes. This is also the site of water reabsorption and B-vitamin synthesis.

Stage of production, e.g. lactating, amount of work, individualism all have an effect on water requirement. A mature horse, weighing about 1000-1100 lb, needs about 10 gallons of water per day for maintenance. A question I often hear is “does the horse need less water in the winter than summer”? If he horse is doing the same work, in the same stage of production, etc, they still need a very similar amount of water winter and summer. One thing often overlooked is how the type of feed that is offered impacts the water consumption. Consumption of lush pasture, containing approximately 70% water, may meet much of the horse’s daily water requirement. However, not all horses are on pasture, but instead are fed hay as the source of fiber/roughage. Hay contains around 10% moisture. Therefore, the horse fed hay would drink much more water than the same horse on pasture to meet their requirement. To illustrate this, take an 1100 lb horse consuming 2% of their body weight per day as feed intake or 22 lb. If he is on pasture containing 70% moisture (30% dry matter), he will eat about 73 lb of pasture, (dry matter/% dry matter = as fed basis), 22lb/.3 dry matter=73lb total feed. This would be 22 lb of dry matter and 51 lb of water. To determine how much water he is consuming, divide the weight of the water by 8lb/gal and you get about 6.4 gal. This is a little over half of his needs. Changing to hay, we would feed 24 lb of hay (22 lb dry matter) but now the water contribution from the roughage source is only 0.3 gal (24lb total feed @ 10% water = 2.4lb water = 0.3 gal). Feeding poor quality forage will also increase the need for more water to help with digesta passage. Another important management note, in winter, the water source the horse depends on may be frozen. Even if only for a day or two, this will increase the chance of an impaction colic. One important thing to remember is snow is not a replacement for water. This will lower the body temperature of the horse and increase energy demand to maintain body temperature.

Another factor is the amount of sand that the horse may be exposed to due to feeding on the ground or even sand in the hay. Many times, I have seen quite a bit of sand in the feeders. While we often remember to supplement with a psyllium product while the horses are pastured or in dirt lots, in winter this may be overlooked. Maintain your feeding program of using psyllium the first 7-days of each month.

Some feed management tips that can help minimize digestive disturbances.

• Always ensure the horse has continual access to clean water. Be sure he is drinking, use buckets, flow meters if on automatic waters, or if on pasture, ensure the horse has access to open water sources. Check heated waterers for any electrical malfunction.
• Change feeds gradually. Take 7-10 days to make feed changes.
• Have the teeth checked annually. Watch for dropped feed or quids.
• Use a quality psyllium product if you suspect the horse has appreciable sand intake.
• Use a quality electrolyte or salt-based product added to the feed daily to encourage water consumption. If on pasture, free choice mineral mixes containing salt or salt only are other options.