Most horse owners are aware that adequate, clean forage is a crucial part of a horse’s diet, and reflects the fact that the horse’s digestive tract has evolved over millions of years to process a trickle feeding intake of high fibre plant material.
Both fresh pasture and preserved forages such as hay and haylage are typically made from grass and other herbage.
Grass and other forage plants are made up largely of two types of carbohydrates:
1. Structural or complex carbohydrates
The cell walls of the plant are designed to structurally support the plant, which increases as the plant matures, providing extra framework and strength to keep the plant upright as it grows!
These structural carbohydrates that make up the cell wall include cellulose and hemicellulose and are typically referred to as digestible fibre.
Of course there are also some parts of the cell wall that even the microbes cannot digest, and this is will be excreted in the faeces and is sometimes referred to as indigestible fibre or roughage.
2. Non-structural carbohydrates (NSC)
Commonly referred to as simple carbohydrates or sugars and starch, these are found inside the plant cell walls, and when the horse chews the plant material, breaking open the cell walls, he can digest these non-structural carbohydrates in the small intestine.
(Some clinical conditions such as Equine Metabolic Syndrome (EMS) and other endocrine disorders, mean that the horse should not receive high levels of non-structural carbohydrates (sugars and starch) in the diet, as they cannot metabolize them correctly, and so these horses and ponies require a diet higher in structural carbohydrates or fibre. This is why hay is often soaked for these horses and ponies, to remove the water soluble, non-structural carbohydrate from the forage before feeding.)
However, most mammals, including the horse, cannot themselves digest the important structural carbohydrate or fibre and rely on the billions of microbes in the gut to digest these cell walls or digestible fibre through a process of fermentation, ultimately breaking the cell walls or fibre down to produce an energy source for the horse.
The maturity of the plant, when eaten or cut for hay or haylage, determines the balance of:
- the readily digestible (small intestine) non-structural carbohydrates (sugars and starch),
- the microbially digested (hindgut) structural carbohydrates (digestible fibre),
- and the indigestible material or roughage,
and affects just how much nutrition the horse or pony can derive from the forage.
Young Spring grass or early cut hays and haylages contains higher levels of easily digestible non-structural carbohydrates (NSC), making it suitable for horses and ponies with higher nutritional needs, such as those in harder work, broodmares during late gestation and peak lactation, and many youngstock.
An older, more mature plant will have higher levels of structural carbohydrates, making it more suitable for horses and ponies who require lower levels of nutrition, and lower levels of non-structural carbohydrates (sugar and starch).
Why is fibre so important for horses?
As fibre is digested by the microbes in the gut, they produce vital nutrients including an energy source that the horse can use, called volatile fatty acids.
This microbial fermentation process also produces heat, helping the horse to maintain his body temperature – feeding forage is the best way to keep horses and ponies warm in cold weather!
Providing plenty of fibre for the microbes to feed on also keeps the whole gut microbiome healthy, and this in turn helps support the horse’s immune system to maintain overall health and well-being.
The microbes also produce some of the key vitamins required by the horse, such as many of the B vitamins, and vitamin K.
Fibre also fulfils other functions to keep the horse healthy:
- The horse needs to chew the forage before swallowing, and this requires the production of large amounts of saliva, which helps to buffer the acid in the stomach.
- This process of chewing provides occupational therapy for stabled horses, as they will chew around 4000-5000 times per kg of hay, and ponies may chew for up to 8000 chews per kg of hay!
- The indigestible or roughage fraction of the forage helps to maintain gut motility – keeping everything moving through the gut!
How can you provide fibre in the horse’s diet?
Pasture, hay and haylage (and occasionally some straw) will provide the majority of the fibre in the horse or pony’s diet and should always be offered at no less than 1.5% of bodyweight on a dry matter basis, unless under professional guidance and monitoring. As outlined above, it is important to choose the right type of forage for the individual to meet but not exceed nutrient requirements.
For example, Native ponies in light work will need forage with a higher fibre content providing a lower level of energy – typically made from older, more mature herbage with a greater proportion of structural carbohydrates. HorseHage High Fibre and HorseHage Timothy are cut later in the season, to provide lower energy levels, and can also be carefully mixed with a proportion of clean straw to further reduce the energy levels if required. HorseHage Ryegrass is cut earlier, from a less mature plant, and therefore has higher nutrient levels, more suited to horses with greater energy requirements, such as harder working horses and broodmares.
Dust levels in some hays may cause exacerbate respiratory allergies or disease, so always check hay is clean and sweet smelling, and not dusty.
Haylages naturally suppress the development of mould spores, and so may be a more suitable forage selection for horses with respiratory concerns. Always chose a reputable haylage producer, with forage produced specifically for horses, with a suitable nutrient specification.
Monitor pasture availability and restrict if necessary (either muzzling, track grazing or strip grazing can be useful methods), but ensure that adequate fibre is provided from other sources if pasture is significantly restricted, to ensure gut motility, chewing time, and gut health is maintained.
Chaffs can provide a useful additional source of fibre, and may be made from straw, grass or other forages such as alfalfa. Chaff may have other ingredients added, such as molasses, oil, herbs, fruits, minerals and vitamins. Once again, it’s important to select the correct chaff for the horse or pony in question, to ensure the nutrient levels are suitable.
An event horse in hard work may benefit from a high energy chaff such as Mollichaff Alfalfa Oil, and a retired Native pony would enjoy Mollichaff Light Molasses Free – a low energy chaff with high levels of fibre and indigestible roughage, to help with gut motility and health, and provide important chewing time.
The highly palatable Mollichaff AppleChaff is a great way to tempt fussy feeders and is another low energy chaff from the Mollichaff Stable.
Chaffs may be offered alone in appropriate quantities as an additional fibre source to provide more chewing time (and nutrition if required), or may be added in smaller quantities to other concentrate feeds to increase the fibre levels.
Both molassed and unmolassed sugar beet, or a combination of sugar beet and grass can also provide increased fibre if required. Be sure to follow directions on soaking before feeding.