Fibre is the structural carbohydrate contained in plants. It is found in the outer cell wall and keeps plant cells intact. Cellulose, hemi-cellulose, pectin & lignin are all carbohydrate molecules made of glucose units, bound by links indigestible by mammalian enzymes. Their energy value is only released by microbial fermentation in the caecum & large intestine. The digestibility of each molecule depends mainly on the age of the plant it is contained in.
Fibre is vital to the horse, it has adapted and evolved to eat grass and is still programmed to survive on an herbivorous diet. Fibre is essential for efficient digestion, the horse cannot digest food properly without it, 50-70% of the diet must be fibre.
The Importance of Fibre in the Horse’s Diet
The horse takes 3000 chews to eat 1kg of fibre, and 1200 chews to eat 1kg of concentrates. Fibre therefore, takes longer to eat, which is closer to the horse’s natural feeding habits. It satisfies the inherent ‘need to chew’, preventing boredom & stereotypies. Increased grinding breaks food down to 1.6mm particles, the larger surface area making digestion easier. The higher chew rate produces more saliva which lubricates food. Silica, found in forage, is naturally abrasive and helps to rasp teeth.
In the stomach, hydrochloric acid is produced even in the absence of food; a trickle fed diet of bulky fibre keeps the stomach 2/3rds full & prevents gastric ulcers. Saliva produced by chewing buffers acid in the oesophageal region of the stomach, keeping bacteria in optimal conditions.
Fibre stimulates contractions of the gut, maintaining the flow of digestive material. In the caecum and large intestine micro-organisms ferment the insoluble carbohydrate. This process produces large quantities of volatile fatty acids, an important source of energy, which are absorbed into the bloodstream. Microbial action also produces some essential vitamins & amino acids. Fibre helps retain water & electrolytes, a valuable reserve for hard exercise/hot weather. Heat produced in the fermentation process keeps the horse warm.
Reasons why a diet high in fibre is vital for the horse:
- It mimics the natural diet, which horse thrives on.
- The horse’s digestive tract is designed to consume fibre, the system functions efficiently.
- Low fibre diet causes problems/illness.
- Keeps the horse’s teeth healthy.
- Prevents boredom.
- Keeps the horse warm.
Cuhna, T.J., (1991) Horse Feeding and Nutrition. Academic Press. California. USA.
Frape, D., (1998) Equine Nutrition and Feeding. Blackwell Science. UK.
Kohnke, J., (1992) Feeding and Nutrition. Birubi Pacific. Australia.
Pilliner, S., (1992) Horse Nutrition and Feeding. Blackwell Science. UK.