The equine species has evolved to live on open grasslands. They are active for much of the time, wandering as they graze, and engaging in locomotory activities. Evolutionary changes to the mouth, teeth and digestive system have resulted in modern horses, who are a species of herbivorous grazers. Their digestive system has evolved to sustain a foraging diet of complex plant materials high in fiber and rich in cellulose requiring extensive fermentation. The large bowel of the equine has evolved to work best when there is an almost constant supply of food making its way through the digestive system and the entire process from ingestion to defecation takes around 48 hours.
The ability of the horse’s digestive system to cope with a diet high in concentrated feed, combined with limited access to forage, is testament to the species’ ability to adapt to ensure its continued survival. Inability to graze, eat a natural diet, and have a constant trickle of food going through the digestive system can result in horses predisposed to a range of physiological and psychological conditions.
Providing adequate nutritional needs in the wrong context does not address the basic needs of the horse or provide the ability to express natural behavior in his movements or the way he eats.
Determining a horse's nutritional requirements has three key aspects:
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