Introduction
As horse owners we are becoming more aware that a great number of horse health and behaviour issues are related to what their horses eat. Healthy digestion is paramount to avoiding ulcers, colic and other problems. Horses possess a unique digestive system that differentiates them from ruminant animals like cows, which have a four-chambered stomach, including a rumen. Horses, as non-ruminant herbivores, have a single-chambered stomach, similar to humans, often referred to as the “simple stomach” or “monogastric” stomach. Their digestive anatomy makes them adept at efficiently digesting forage such as grasses and hay but less suited for processing concentrates or hard feed, which can include grains like oats, corn, and barley. This paper emphasizes the critical role of natural feeding in maintaining a horse’s digestive health and explores the implications of modern feeding practices on their well-being.
Fundamental Anatomy
Understanding the digestive system of the horse is fundamental to making sure that your horse has a healthy digestion.
The equine digestive system can be classified into two primary sections: the foregut and the hindgut. The foregut comprises the stomach and small intestine, while the hindgut, or large intestine, consists of the caecum and colon. In its entirety it is referred to as the Gastrointestinal (GI) tract
Mouth: Mastication, or chewing, is the first stage of digestion where feed is ground down to allow enzymes and bacteria to attack the cell walls of the horse’s plant-based diet.
Stomach: Remarkably, the equine stomach can only accommodate 2-3 gallons at a time, making it the smallest stomach relative to body size among all our domesticated animals. Depending on the size and content of the meal, such as hay versus grain versus liquids, food may reside in the stomach for as little as 15-30 minutes or as long as 12 hours, with an average of 3-4 hours.
Small Intestine: Moving down the digestive tract, we come to the small intestine, which stretches approximately 70 feet in length and comprises three parts: the duodenum, jejunum, and ileum. Food can traverse the entire small intestine in as little as 30-60 minutes but may take up to 8 hours.
Caecum: Continuing into the large intestine, the first stop is the caecum, a structure resembling a fermentation vat, akin to a cow’s rumen. This comma-shaped component on the horse’s right side is roughly 4 feet long and can hold 8 gallons.
Colon: The order of progression then moves to the large colon (10-12 feet long) and the small colon (also 10-12 feet long). The time taken for food to pass through the entire hindgut can range from less than a day to as many as 3 days.
The Equine Digestive Process
Given the distinct functions carried out in the front and back of the gastrointestinal tract, it is prudent to examine each part separately.
Foregut Digestion
Mouth
The physical action of chewing activates the three pairs of salivary glands in the horse’s mouth. This is the only time saliva is produced in horses. Saliva production in horses, just as in humans, is critical in helping the swallowing process and preventing choking. The more chewing, the more saliva that is produced.
Stomach
After horses gather, chew, and swallow their food, the stomach comes into play. The bicarbonate produced by the salivary glands protects the stomach from acid damage and contains small amounts of amylase which starts the breakdown of carbohydrates.
The upper 1/3 of the stomach, known as the “non-glandular region,” is where 80% of ulcers form. It relies on mucus and buffers from saliva to protect it. It lacks protection from stomach acid, unlike the lower, glandular section. The glandular region continuously produces hydrochloric acid which further breaks down food. Pepsinogen and stomach acids initiate the digestion and degradation of fats and proteins. The stomach mixes the food and regulates its passage via muscular contractions known as peristalsis. Essentially, the stomach acts as a holding and mixing tank, much like a cement truck continuously churning and blending ingredients.
Small Intestine
Most proteins, soluble carbohydrates and fats are broken down by digestive enzymes in the small intestine. The pancreas releases amylase into the small intestine for carbohydrate breakdown. Proteases continue the breakdown of proteins into amino acids. Bile from the liver helps emulsify fats into smaller globules. The nutrients are then absorbed into the bloodstream through the intestinal villi.
Healthy villi in the small intestine allow for maximum absorption of nutrients, but the tiny villi are sensitive to certain medications, parasites, and excess stomach acid. When cells in this area are damaged, the membrane barrier is compromised, allowing toxins and large molecules into the bloodstream (this is often referred to as ‘Leaky Gut’). This can result in body inflammation and suppressed immunity. Other health issues resulting from foregut issues include ulcers, laminitis, colic, GI tract inflammation and malabsorption of nutrients among other metabolic issues.
Hindgut Digestion
Fermentation in the hindgut enables most of the horse’s food digestion. What is being fermented is complex carbohydrates (fibre) into useful end products with the assistance of beneficial microorganisms. These microorganisms produce fatty acids, supplying energy and calories, as well as B-vitamins, Vitamin K, and some amino acids. The colon plays a dual role, absorbing these nutrients and a portion of the water accompanying food as it traverses the digestive tract.
Horse Digestive Problems
With such complexity in the equine digestive system, it’s unsurprising that issues occasionally arise. Nevertheless, the intricate nature of a horse’s digestive tract should not deter owners from maintaining a healthy system.
Gastric ulcers, characterized by erosions in the stomach lining, result from extended exposure to irritating acids on sensitive tissues. While short-term prescription medication may promote tissue healing, long-term management necessitates a combined approach involving pharmaceuticals, natural remedies, and dietary and lifestyle changes to preserve stomach health.
The PH and balance of microorganisms is critical to proper hind gut function. And that balance is easily disrupted. Situations that lower PH, creating an acidic environment or causing death to a portion of the microbiome can result in the release of endotoxins into the bloodstream potentially causing an array of issues including laminitis, founder, colic and leaky gut.
“Colic” is a general term denoting abdominal pain without specifying a cause or location in the horse’s belly. However, mitigating known risk factors, such as sudden changes in hay or grain, excessive grain consumption, abrupt shifts in activity, prolonged periods of stall confinement, inadequate parasite control, and restricted access to water, can significantly contribute to a smooth operation of the horse’s GI tract. On the other hand, prebiotics, enzymes, and yeast have shown their ability to support normal hindgut function.
The good health of the microbiome (bacteria and protozoa colonies) and having an adequate amount of water in the hindgut are two critical components to healthy equine digestion. Too little water intake can cause an excess of undigested material and result in impaction colic. Too much water remaining in the system can lead to diarrhoea.
Continual exposure to low PH can cause anorexia or malnutrition, colitis (inflammation of the colon) and other metabolic disorders.
Physical signs of hindgut issues may include a swollen caecum (right side in front of the hip), difficulty bending to the right under saddle, gut agitation and loose manure. If the caecum has an acidic environment, this can spill over into the large intestine causing damage, which can lead to diarrhoea, dehydration, poor absorption of nutrients, colic, ulcers and colitis.
The Role of Natural Feeding
Given these limitations in their digestive system, it’s crucial to carefully manage a horse’s diet to ensure their well-being. When feeding concentrates or hard feeds to horses, the following factors should be considered:
Gradual Introduction: If concentrates are a necessary part of the diet, they should be introduced slowly and in small amounts to allow the horse’s digestive system to adapt.
Balanced Diet: A horse’s diet should be balanced, with the appropriate ratio of forage to concentrates. The quality of forage should be a priority.
Monitoring and Management: Regularly monitor the horse’s body condition and adjust the diet as needed to maintain a healthy weight.
Avoid Overfeeding: Overfeeding concentrates, especially high-starch feeds, should be avoided to prevent digestive disturbances and health issues.
Importance of Stable Blood Sugar Levels
Natural feeding plays a pivotal role in maintaining stable blood sugar levels. Horses are grazing animals, exhibiting a lower tolerance for blood sugar instability compared to humans. Stable blood sugar levels in horses lead to natural digestion, balanced mood, stable energy, and healthy tissue rebuilding.
Modern feeding practices, with highly processed feeds, can disrupt stable blood sugar levels and contribute to various issues, including ulcers, excessive weight gain, decreased energy, skin problems, allergic reactions, and decreased muscle mass. Concentrated raw grain-based feeds, unnatural for horses, can lead to the fermentation of raw starch content in the hindgut, resulting in alcohol production and subsequent spikes in blood sugar.
Balanced Diet Components
A balanced horse diet should consist of the following components:
Forage: High-quality forage, such as good pasture or hay, forms the foundation of a horse’s diet. Forage provides fiber, energy, and essential nutrients. Horses should have access to forage throughout the day.
Concentrates: Concentrates, such as grains or pelleted feeds, can be added to the diet for horses with higher energy requirements. These should be chosen based on the horse’s activity level, age, and specific needs.
Protein: Horses require a balance of essential amino acids for muscle development, coat health, and more.
Vitamins and Minerals: Forage may not always provide all necessary vitamins and minerals. The specific needs depend on the horse’s age, activity, and the forage quality.
Water: Adequate clean, fresh water is essential for digestion, temperature regulation, and overall health. Horses can consume a significant amount of water daily, so access to water is crucial.
Electrolytes: Horses that sweat heavily may need electrolyte supplements to replace lost minerals. These supplements are often used during hot weather or strenuous exercise.
Fat: Adding fat to the diet can increase energy content without increasing the risk of colic associated with large grain meals.
Salt: Providing access to plain white salt (sodium chloride) allows horses to regulate their sodium intake according to their needs.
Conclusion
In conclusion, understanding the unique digestive system of horses and the implications of modern feeding practices is essential for promoting their overall well-being. Natural feeding, with a focus on high-quality forage and minimal starch and sugars, is vital in maintaining their digestive health. Stable blood sugar levels are crucial for horses, and natural feeding helps achieve this stability, ensuring balanced digestion, mood, and energy, while reducing the risk of various health issues associated with unstable blood sugar levels. Careful diet management, gradual introduction of concentrates, and regular monitoring of a horse’s body condition are fundamental steps in ensuring their health and longevity.
The Horses’ Digestive System
Horses are herbivores that have evolved a unique digestive system adapted to break down cellulose and extracting nutrients from it. Horses have a relatively small stomach and a large caecum and colon, which allow for slow and thorough fermentation of fibrous plant material. It’s essential to feed horses a diet that is appropriate for their digestive system. Such a diet is primarily composed of high-fibre forage. If you need to add additional calories to your horse’s diet, it’s best to do so with fats or high-fibre feeds, such as beet pulp, rather than high-starch grains. Horses have a much lower tolerance to blood sugar instability than humans. They are not designed to eat meals and therefore stable blood sugar is paramount for their health, energy, and longevity. This article delves into the significance of starch in a horse’s diet, its recommended quantity, and the potential dangers of feeding high-starch diets.
Understanding Starch in a Horse’s Diet?
Starch is a complex carbohydrate that is broken down by enzymes into simple sugars in the small intestine.
The Role of Enzymes: Enzymes are the molecular workhorses that facilitate the transformation of starch into simpler, more readily usable forms. In the context of starch digestion, two critical enzymes come into play:
• A mylase: Amylase is an enzyme produced in various parts of the horse’s digestive system, including the salivary glands and the pancreas. The salivary amylase is secreted into the mouth, where it begins the initial stages of starch digestion as the horse chews its feed. However, the primary amylase activity takes place in the small intestine, where pancreatic amylase is released.
• Maltase and Isomaltase: These enzymes work in tandem to further break down the partially digested starch molecules into simple sugars like glucose. These enzymes are located on the brush border of the small intestine’s absorptive cells, which are specialized for nutrient absorption.
The Starch Breakdown Process: The process begins in the horse’s mouth as it chews its feed. Salivary amylase initiates the breakdown of starch into shorter carbohydrate chains known as dextrin. The partially digested feed then enters the horse’s stomach. However, starch digestion temporarily pauses here because the stomach’s acidic environment isn’t conducive to the activity of amylase enzymes. Once the feed passes into the small intestine, it encounters a more neutral pH environment. This is where pancreatic amylase takes centre stage. Pancreatic amylase further breaks down the dextrins into maltose, a disaccharide composed of two glucose molecules, and other simple sugars. As the maltose and other smaller sugar molecules are produced, they are absorbed across the intestinal wall. This is where maltase and isomaltase, located on the brush border of the absorptive cells, come into play. They split the maltose into individual glucose molecules, which can be readily absorbed into the bloodstream.
The Significance of Starch Digestion
This intricate process of starch digestion is critical for providing horses with the energy they need for various activities, from grazing and foraging to athletic performance. The enzymatic breakdown of starch ensures that the horse’s body can efficiently convert this complex carbohydrate into glucose, which is the primary fuel source for muscles, organs, and various metabolic processes.
Recommended Starch Levels
The ideal starch and sugar levels in a horse’s diet depend on various factors, including age, activity level, and overall health. As a general guideline, it is advisable to aim for a feed that contains less than 10% combined starch and sugar. Its therefore essential to manage starch intake carefully, as excessive starch in the diet can overwhelm the digestive system.
The Dangers of Feeding a High Starch Diet
When excess starch is fed that cannot be converted into simple sugars in the horse’s small intestine it passes undigested into the caecum and colon. When this happens, the undigested starch can cause a rapid fermentation of the fibrous material in the hindgut, leading to an overgrowth of harmful bacteria and an increase in the production of lactic acid. The lactic acid can lower the pH in the hindgut, leading to a condition called hindgut acidosis. Hindgut acidosis can cause gastro-intestinal inflammation and damage to the lining of the hindgut which can lead to colic, laminitis, and diarrhoea.
In addition to hindgut acidosis, a high starch diet can also cause insulin resistance, which is a condition where the horse’s body becomes less responsive to insulin. In simple terms the alcohol spikes the blood sugar, which in turn drives cortisol outside its normal reference range producing a state of relative catabolism. Unfortunately, blood sugar imbalances are getting increasingly common because of highly processed feeds. These imbalances lead to insulin resistance can also contribute to laminitis and obesity, decreased energy, skin issues, allergic reactions, or decreases in body weight, especially muscle mass.
Apart from acidosis and the related problems high starch diets are often the root cause of other conditions:
- Laminitis: Horses consuming such diets are at an increased risk of laminitis, a painful hoof condition leading to lameness.
- Insulin Resistance: Metabolic disorders like equine metabolic syndrome and Cushing’s disease can result from high-starch and sugar diets.
- Weight Gain: These diets can be calorie-dense, leading to obesity if not balanced with exercise and dietary management.
- Behavioural Issues: Horses on high-starch and sugar diets may exhibit behavioural changes, including hyperactivity or lethargy.
In general, it’s advisable to limit the combined starch and sugar content of horse feed to 10-15%.
The Relationship Between Acidosis and Gastric Ulcers
Hindgut Acidosis and Gastric Ulcers: While hindgut acidosis and gastric ulcers are distinct conditions, they can be interconnected. Hindgut acidosis, characterized by hindgut inflammation and damage, can indirectly influence stomach health by altering pH levels and bacterial populations. Additionally, high-starch diets can stimulate gastric acid production and decrease stomach lining protection, increasing the risk of ulcers.
Dietary Control of Gastric Ulcers
Diet plays an important role in both the prevention and treatment of horse ulcers. A well-balanced diet that is appropriate for the horse’s individual needs can help maintain the health of the digestive system and reduce the risk of ulcer development. Feeding practices that can help control horse ulcers include:
- Providing frequent, small meals: Horses are natural grazers and have evolved to eat small amounts of forage frequently throughout the day. Providing frequent, small meals can help buffer the stomach acid and reduce the risk of irritation and ulcer development.
- Low Starch & Sugar Diet: As explained feeding a high starch diet has been linked to an increased risk of gastric ulcers in horses. Reducing starch and increasing forage intake can help maintain a healthy digestive system and reduce the risk of ulcer development.
- Providing access to forage: Providing access to forage throughout the day is an important part of maintaining the health of the digestive system. Forage provides fibre that helps maintain the health of the hindgut and stimulates saliva production, which helps buffer the stomach acid.
- Avoiding abrupt changes to the diet: Abrupt changes to the diet can disrupt the microbial population in the digestive system and increase the risk of digestive upset and ulcer development. Any changes to the horse’s diet should be made gradually over several days or weeks.
- Managing stress: Stress has been linked to an increased risk of ulcer development in horses. Managing stress through appropriate management practices, such as providing turnout time and socialization, can help reduce the risk of ulcer development.
Pure Feed – A Dietary Solution
Pure Feed is a company specializing in horse feed made from high-quality, natural, palatable ingredients. It aims to balance a horse’s diet by providing essential nutrients, fibre, and calories. Pure Feed is designed to promote stable blood sugar levels, mirroring a grazing animal’s natural diet. It contains no molasses and maintains low starch and sugar levels, typically less than 10% combined. You choose what you do with your horse and there is an equivalent feed with matching energy and support to go alongside. If you are looking for a feed without Alfalfa, then Pure Feed is the one for you.
Benefits of Pure Feed
- Improved Digestion: Pure Feed’s digestible composition enhances overall digestive health, reducing the risk of digestive issues such as hindgut acidiosis, colic and gastric ulcers.
- Enhanced Nutritional Profile: With a blend of high-quality ingredients and herbs, Pure Feed improves nutritional content, providing essential vitamins, minerals, and nutrients for horse well-being.
- Reduced Risk of Laminitis: Low starch and sugar content in Pure Feed help mitigate the risk of laminitis in susceptible horses.
- Improved Coat and Hoof Health: Natural ingredients in Pure Feed promote healthy coat and hoof growth, preventing issues like dry, brittle hooves or a dull coat.
- Increased Energy: Pure Feed provides the necessary energy for optimal performance without causing abrupt energy spikes that can lead to behavioural problems.
Conclusion
At Stockley we understand the role of starch in a horse’s diet, and why it is crucial for their overall health. Maintaining appropriate starch levels and following dietary guidelines can help prevent issues like hindgut acidosis, gastric ulcers, and related health complications. Products like Pure Feed offer a balanced, low-starch alternative to support a horse’s well-being, emphasizing the importance of a suitable diet tailored to individual needs.