Do you understand the function of your horse's digestive tract and do you know how you can maintain a healthy tract through your feeding practices? We look at how managing feed can greatly influence the health of the digestive system.
Grazing is a natural pattern of eating for our horses, known as trickle feeders, they will not naturally consume large meals at once but small meals throughout the day. The introduction to cereals and protein concentrates has required our horse’s digestive tracts to evolve with these new management practises. Commonly during the colder weather, horses spend more time confined to a stable with limited access to food, often less than three times a day. It is important that as horse owners we understand the function of the digestive tract to help prevent health issues associated with current feeding practices.
The lips, tongue and teeth are all key in the first stages of the digestive process. The upper lip contains a strong, sensitive muscle used to place forage between the teeth. Mastication (or chewing), breaks down the food particles to smaller sizes suitable for swallowing. Studies have reported that a horse will chew between 3000 and 3500 times, whilst a pony can chew up to 5000 to 8000 times when eating 1kg of hay. Saliva is a key part of the digestive process; the presence of food matter generates saliva production with up to 10 to 12 litres of saliva being produced by a horse per day. Saliva has three main functions; lubrication to prevent choking, it aids the formation of a bolus (small food ball to allowing easy swallowing) and creates a buffer for the acidic conditions present within the proximal region of the stomach.
The oesophagus connects the mouth to the stomach, it is made up of a muscular tube creating contractions to push the digesta into the stomach through the cardiac sphincter. This valve is specifically designed to stop the food from passing back out of the stomach, hence why we rarely see horses vomiting.
The stomach is a small organ of the digestive tract, with food passing through quickly and is rarely completely empty of digesta. The stomach can be divided into two regions; the first being the non- glandular dorsal region of the stomach lined in squamous epithelium. The second region is known as the glandular ventral region lined in glandular epithelium, which can be further divided into the fundic and pyloric regions. Gastric ulceration can be a result from prolonged exposure of gastric juices to the stomach lining, known as the gastric mucosa, resulting in ulceration and bleeding, commonly seen in the dorsal region. Ulceration within the ventral region is unlikely to be diet related and often a side effect of medication such as non-steroid anti-inflammatory treatment. Prolonged periods of fasting leads to excessive gastric acid output without adequate saliva production. A study showed horses fed a hay diet had a reported 3.1 pH compared to fasted horses reporting 1.5 pH levels within the gastric acid of the stomach. Saliva produces a natural buffer for these acidic conditions, by maximising the amount of time spent chewing, we can increase the amount of saliva being produced.
The Small Intestine
The small intestine can be split into three separate parts; Duodenum, jejunum and the ileum. Approximately 21 metres in length, the rate of food passage can be as short as 15 minutes. The main digestion of fats, starches and proteins occur in the small intestine by enzymatic breakdown processes.
Starch is mainly digested here, however studies have reported that an increase in starch content within the diet can lead to less starch digested in the small intestine. High levels of starch digestion can lead to a decrease in pH due to the accumulation of lactic acid, resulting in the disruption of mucosal membranes and microbes of the large intestine, these alterations can result in health problems developing such as hind gut acidosis or laminitis. The processing techniques used on starch-based products can impact the preceal digestibly.
Fats are also absorbed in the small intestine by the breakdown of fat particles from Bile which is continuously secreted to the small intestine from the liver. The bile emulsifies the fat which is then absorbed into the lymph system.
Protein is made up on long chains of amino acids, enzymatic functions break down these chains for absorption. Pancreatic juices containing these enzymes, are released into the small intestine, consisting of an alkaline buffer from the acid conditions of the stomach.
The Large intestine
Further divided into three sections; ceacum, colon and rectum, the large intestine is the site of structural carbohydrate digestion such as forages and other fibre sources, known as microbial fermentation. A symbiotic relationship between the horse, protozoa and bacteria help to break down the fibrous products into volatile fatty acids.
The ceacum acts as a fermentation vat, holding between 25 to 35 litres. During the fermentation process vitamin B and K are naturally synthesised, as well as the generation of heat. Therefore, in the colder weather it is more beneficial to provide your horse with extra hay than cereal feeds.
The large colon is 3.5 meters in length, due to it’s size this causes the large colon to fold back on itself, these pose a high risk of food impaction and digesta flow disturbances. The small colon however is 2.5 metres, the absorption of water and electrolytes occurs here, vital for normal muscle function. Finally, undigested material is stored within the rectum and expelled through the anus.
There are simple feeding practises that we can carry out to ensure our horses digestive tracts are kept healthy. Firstly by ensuring we provide sufficient fibre within their diets, it is recommended that a 500kg horse is provided 1.5 – 2% of body weight in forage per day. Feeding little and often to imitate their natural eating habits, ideally, we want our horses out grazing all year long, but this isn’t always possible. We can increase chewing times by alternative feeding methods such as haynets or trickle feeders. Consider alternative sources of energy rather than high cereal based feeds, such as the inclusion of oils and super fibres (such as soya hulls and sugar beet).
High cereals diets should be avoided, it is important to consider the horses requirements, workload and status when designing a diet plan.
Let our experts guide you. Use our tailored diet plans and a Bluegrass Horse Feeds equine feed consultant will provide you with a tailored diet plan to suit your horses' needs
Bluegrass Horse Feeds is an Irish horse feed producer based at its mill in Eglish in County Tyrone. Bluegrass Horse Feeds, which produces quality and innovative horse feeds, is the Ireland Team Member of Kentucky Equine Research. The Bluegrass Horse Feeds team works closely with owners, riders and trainers using the latest nutritional research and technology to achieve optimum performance from their horses. Bluegrass distributes its feeds the length and breadth of Ireland and has over 200 stockists. If you need nutritional advice please fill out our diet request form and while you're here find out your nearest stockist.