Peristalsis contractions are responsible for moving food through the digestive tract allowing the breakdown and absorption of nutrients at various points within the system. Fibre absorbs water and helps to lubricate the gut providing a transit material for other food stuffs. Fibre indirectly and importantly supports immune function and supports water balance. For the Horse fibre is an energy source too.
The fibre mass is digested in the last section of the gut the large Intestine; the caecum, the large colon and the small colon. The horse is a hind gut fermenter and it takes a considerable amount of fibre to support its high calorific requirements. Research shows that to keep good gut function horses must consume at least 1.5% of bodyweight as fibre. Preferably, we would aim for 2% of bodyweight. At maintenance when other feeds are not provided this may be 2.5-3%. Typically, for a 16 hh horse with a 500kg bodyweight in light to medium light work this is in the region of 10kg per day, on a dry matter basis. This figure should take in to account all the fibre sources in the diet. Including grass, preserved forages such a hay or haylage, chaffs and sugar beet.
Forages that are fed to horses contain both nonstructural carbohydrates known as sugars and starches, and structural carbohydrates. Both are important in the correct amounts. The fibres that we are concerned with for good gut function are the structural carbohydrates such as cellulose, hemicellulose and pectins. It is these nonstructural carbohydrates that are fermented by desirable species of bacteria, which in turn naturally produce short chain volatile fatty acids (VFA). The majority of Volatile Fatty acids are absorbed in the hindgut and are converted to glucose and fat. Which are used as energy. When a combination of different fibres are consumed they support a wider variety of the good bacteria required for the process of fermentation and digestion.
It is good practice to add chaffs such as alfalfa with sainforin (also called fibre fusion) or alfalfa Plus Oil as these encourage chewing promoting saliva production which can help buffer gastric juices assisting normal digestion. Alfalfa and sanforin, provide highly digestible fibre, which means they contribute well to energy requirements together with quality protein, and bioavailable calcium. Surprisingly they are low in sugar. Unmolassed Sugar beet also provides digestible source of fibre and can be used as an alternative. All these products are high in soluble fibre or digestible fibre and are broken down almost completely in the hind gut without over stimulating insulin.
Perhaps surprisingly, some hardworking horses stop eating their required intake of hay or forage even though as performance horses they have increased energy or mega calorie requirements; this may cause weight loss and trigger problems such as ulcers so is something to be aware of. These performance horses often have a smaller appetite for the essential long fibre and preserved forage.
Again, this is another reason to add chopped forages to equine meals. An equally important point is that a variety of fibres will support the large diversity of hind gut bacteria that ensures healthy digestion. This is why you will see in the feed composition list fibres such as, alfalfa, beet pulp, sainfoin, oatfeed, wheatfeed, grass etc. An important ingredient to the Dodson and Horrell’s Fibre Fusion is the Fibre plus complex pellet, which further supports essential fermentation.