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The Wondrous Hindgut Of A Horse

CAROL SHWETZ

DVM

These large

1,000-pound animals owe most of their life-sustaining energy

to billions of friendly micro-organisms,

all linked in a co-operative,

benevolent relationship.

There is no particular part of a horse’s body that is any more important than another, yet the happenings within a horse’s hindgut seems to shape a horse’s attitude, immune function, and influence expressions of health and performance. If your horse’s belly is happy, chances are your horse will be happy. The hindgut is truly at the hearth of a horse.

Horses have a unique digestive strategy. Their cecum and colon, two structures known collectively as the hindgut, serve as large fermentation vats. Together they represent about 65 per cent of the horse’s entire digestive tract. In this 25-to 30-gallon space, populations of microbes numbering in the billions contentedly digest plant fibre into energy, working in exchange for a warm, comfortable living space.

The horse’s digestive tract is designed to effectively move plant material to the hindgut where bacteria, protozoa, yeast and other healthy microbes produce enzymes which break down fibrous plant material into volatile fatty acids or VFAs. These very short-chain fats are used by the horse and micro-organisms for energy. Horses on total-forage diets receive up to 70 per cent of their energy from these VFAs.

The horse’s cecum is dedicated to producing most of the energy and/or fuel. These large 1,000-pound animals owe most of their life-sustaining energy to billions of friendly micro-organisms, all linked in a co-operative, benevolent relationship. A functional cecum also produces significant amounts of B-vitamin complexes. These B vitamins are vital to many functions within the body. Most notable is their support for the nervous system, which results in their having a calming influence on the horse.

FIBRE, NOT GRAIN

The equine digestive system works best when horses are mainly fed long-stem grasses or hay. However, when excess grains and rich, concentrated feeds are fed to the horse, they are inadvertently moved along to the hindgut where they ferment. An acidic lactic acid cocktail results, which disrupts the natural balance of microflora in the cecum. This kills off beneficial bacteria and so encourages the growth of unfriendly bacteria. These lactic acids irritate and damage the delicate lining of the hindgut, making it abnormally permeable. This can cause a number of problems in horses, including refusal to eat, colic, laminitis, diarrhea, and stereotypic behaviours such as cribbing and weaving.

The horse’s digestive system has evolved to process large amounts of high-fibre forage, rather than today’s richer diets.

Feeding practices, stressors such as travel or changing herd mates, medications, chemical dewormers, vaccines and steroids all alter the delicate and at times precarious microbial balance within the hindgut. Often this results in alterations to the horse as a whole whether it be attitude, health, or performance.

Key management practices that can aid in keeping your horse’s hindgut healthy and happy include the type of feed and how often it is fed. Feed plenty of high-quality long-stem fibre, which is the mainstay of a horse’s diet. It maintains the presence of the fibre-digesting bacteria. Horses are trickle feeders and prosper when allowed to eat throughout the day.

Feed according to the work. Plenty of exercise and movement are favourable for gut motility. Make changes to the diet gradually. This will allow the bacteria to adapt. Ensure plenty of fresh water is readily available as the entire digestive process “runs on a river.”

These horses are able to maintain gastrointestinal tract normalcy, reducing chances of colic, stable vices, health and behaviour problems.

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