Horses, as herbivores, have a unique and complex digestive system. It is essential to understand how a horse's digestive system works to ensure their proper nutrition, health, and overall well-being. Horses are non-ruminant herbivores, meaning they do not have multi-compartmented stomachs like cattle; they have single-compartment stomachs like humans. As herbivores, their diet consists primarily of plant material.
The Dual-Phase Horse Digestive System
A horse's digestive system is unique because it processes food in two distinct phases: enzymatic digestion in the foregut and fermentation in the hindgut. This dual-phase digestion sets horses apart from other animals. The foregut functions similarly to the pre-caecal equine digestive system of monogastric animals like dogs, humans, and pigs, while the hindgut operates like a cow's rumen.
In this article, you will explore facts about a horse's digestive system to better understand its eating habits, overall dietary needs, and digestive processes.
The foregut
The foregut of a horse consists of the mouth, esophagus, stomach, and small intestine. Let’s understand them in brief:
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Mouth and Teeth
The equine digestive process begins in the mouth, where horses use their lips, tongue, and teeth to grasp and chew food. Their teeth are specifically designed to grind down fibrous plant material. Saliva, made by three pairs of salivary glands (parotid, submaxillary, and sublingual), helps moisten and break down the food. Horses produce 10-15 gallons of saliva daily, which aids in forming a bolus for easy swallowing.
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Esophagus
The esophagus is a muscular tube about 1.5 meters long that transports chewed food from the mouth to the stomach. Due to its length and the horse's inability to regurgitate, it is crucial to ensure food is adequately chewed to prevent choking.
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The Stomach
Horses have a single-chambered stomach and are naturally designed to frequently eat small amounts of roughage. Modern feeding practices, which often involve large grain meals once or twice a day, can negatively impact their digestive health.
Feeding horses small, frequent meals improves their digestive efficiency. When a horse consumes a large meal, the feed may pass through the stomach in as little as 15 minutes, while fasting can result in a 24-hour clearance time.
Providing fresh, clean water at all times is optional, but it's a fundamental responsibility. Modern feeding practices often leave horses with empty stomachs for extended periods, which can be harmful and lead to stomach upset, digestive issues and sometimes ulcers. To reduce the risk and complications of stomach ulcers, it is best to feed horses a diet high in roughage, provide small, frequent meals, and allow them to graze as much as possible.
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Small Intestine: Digestion and Absorption
The horse's small intestine, which comprises 28% of its digestive tract, is where most digestion occurs. It involves three sections: the duodenum, jejunum, and ileum.
Enzymes from the pancreas aid break down proteins, fats, starches, and sugars. Nutrients are absorbed through the small intestine's walls and carried by the bloodstream to where they are needed. It is crucial not to feed horses moldy or spoiled feeds. Additionally, high-quality protein containing essential amino acids is vital for horses with high protein demands.
Can horses vomit Due to Poor Digestion?
Unlike humans, horses can't vomit. This is due to a combination of anatomical and physiological factors. A primary reason is a solid one-way valve (the lower esophageal sphincter) between the esophagus and the stomach.
This valve stops food from moving back up the esophagus. Also, the angle at which the esophagus enters the stomach makes it nearly impossible for its contents to be expelled upward. This inability to vomit makes horses more susceptible to conditions like colic if they ingest something harmful or if their stomach becomes overly full or upset.
The Hindgut
The hindgut comprises the cecum, large colon, small colon, rectum, and anus. It spans approximately 7 meters and has a 140-150 liters capacity.
This is the part of the horse's digestive system where most digestion occurs. Digestion in the hindgut is primarily due to microbial rather than enzymatic activity. Billions of symbiotic bacteria in the hindgut efficiently break down plant fibers and undigested starches into simpler mixtures called volatile fatty acids (VFAs), which are absorbed through the gut wall.
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Cecum
The cecum is a fermentation vat located at the junction of the small and large intestines. It is about 4 feet long and holds 30-35 liters of feed and fluid. Microbes in the cecum break down fibrous materials into volatile fatty acids (VFAs), a vital energy source for horses.
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Large Colon
The large colon, approximately 10-12 feet long, continues fermentation. It has four sections and a capacity of around 86 liters. Microbial digestion in the large colon produces more VFAs and absorbs water, which helps maintain hydration.
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Small Colon
The small colon, around 10 feet long and 10 cm wide, absorbs the remaining water and forms solid waste (feces).
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Rectum and Anus
The rectum stores feces until they are expelled through the anus. The digestive process, from ingestion to excretion, takes 36-72 hours.
Digestive System Facts to Remember About Horses
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Horses have one stomach. They are monogastric animals, meaning they have a single-chambered stomach, unlike ruminants like cows, which have multiple stomach compartments.
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Since horses have smaller stomachs, feeding them numerous small meals throughout the day is best.
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Be careful with the feed quality. Poor quality feed may contain harmful substances, which, if ingested by horses, can cause digestive upset or colic.
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Unlike humans, horses cannot vomit.
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Sudden changes in diet can alter the bacterial population in the horse's hindgut, potentially leading to colic and reduced digestive efficiency.
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The equine gut is susceptible and can easily be disrupted, with colic being the leading cause of equine mortality.
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Maintaining a healthy microflora can be challenging if a horse is under stress, traveling long distances, recovering from illness or injury, receiving antibiotics, being weaned, or consuming large amounts of grain.
Conclusion:
By understanding the horse's digestive system, horse owners can make informed decisions about feeding practices, ultimately promoting better health and performance for their horses. Alongside proper nutrition, supplements containing, probiotics, prebiotics and yeast cultures can help support normal digestive function and health.
Digestive health and support questions?
At MedVetPharm, our experts can help you select the best supplements and feeding practices for your horse. Call us at 833-809-4848 or contact us here.
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