From Intake to Nutrient Absorption: The Path of Feed Through the Horse's Body

The journey begins in the mouth where the feed is chewed and mixed with saliva. Chewing is crucial so the feed is sufficiently broken down and moistened before it passes through the oesophagus; otherwise, there's a risk of it getting stuck. Thus, horses need ample time as well as peace and quiet during feeding. The saliva contains no enzymes but does have buffering substances that are important further down in the digestive process. The oesophagus connects the mouth to the stomach.

In the stomach, the feed comes into contact with acidic gastric juice which adds enzymes. Horses can neither vomit nor burp, so if excessive gas forms, it can cause gas colic. The risk of gas formation increases with large quantities of starch that do not have time to be digested. Moving into the small intestine, bile is added to digest fats, and bicarbonate from the pancreas supplies enzymes and raises the pH level. The passage through the small intestine is rapid, and along the way, easily digestible nutrients such as sugars and starch are extracted.

The large intestine, consisting of the caecum and colon, is where most nutrient extraction occurs. The passage here is slow, and the microorganisms work over approximately three days. The balance among them is vital for optimal digestion of the feed. There are many causes for issues, such as overfeeding of easily digestible nutrients (like starch), stress, medications, etc. A sign that digestion is functioning can be seen in the faeces, which should consist of firm balls. Wet faeces or a bad smell are often indicators that something is not working optimally. If there is a suspicion that the horse is ingesting sand or gravel, this can be tested by soaking a ball in a bag and feeling for particles at the bottom of the bag after some soaking time.