Equine Nutrition

Claire. M. Galer - BSc(Hons) E.Sc ITEC Dip Hu. IGPP. ITEC Dip MESMA

Equine Nutrition

In order to perform at their best, a horse must be fed a diet that supplies all necessary; Energy, Protein, Vitamins & Minerals. Nutrition is more than just balancing nutrients in the diet, there are many aspects involved………

Equine Diet Specification Depends On Many Factors:

Working Horse primary’s concern is energy intake. Broodmare most demanding equine in terms of nutritional requirements, last 90 days of gestation the mares needs are increased. With energy requirements 12% higher than maintenance levels.

The appropriate selection of feeds & providing a balanced diet is essential. Together with providing access to fresh clean water at all times. Horses are creatures of habit & regular feeding times help to reduce stress & digestive problems.

Equine Evolution

The horse has been evolving over 60 million years, has been domesticated under 5,000 years, has been kept stabled under 500 years & has been kept in large numbers on small fixed acreage for under 100 years.

Is The Feeding Of The Equine An Art Or A Science….. ?

By enlarge, equine rations are based on scientific evidence. However there is a great deal of art to the feeding of the equine. In the words of Professor William Henry 1901 “The skill of the artist horse feeder enters into the very life of the creatures he manages, along with the food he supplies”

EQUINE DIGESTIVE SYSTEM

Understanding the digestive system of the horse is essential for effective feeding & management. The equine digestive tract extends from the mouth to the rectum & can be divided into different components.

  • The Mouth & Teeth
  • Oesophagus
  • Stomach
  • Small Intestine (Duodenum, Jejunum & Ileum) & The Large Intestine ( Caecum, large Colon, Small Colon & Rectum)

Equine Digestive Tract


The Mouth & Teeth

The wear of teeth is significantly affected by diet, with high levels of concentrate feed being associated with uneven wear. Regular dental care is essential for good nutrition, poor teeth are a major cause of thin horses. Improperly chewed food can lead to choke or colic.

Chewing Rates

Different types of feed require different amounts of chewing, with forages taking many more chews than concentrate feed. Ponies chew many more times for the same amount of feed than horses. Study at Royal Dick Veterinary College, Edinburgh (1998) Dr Derek Cudderford Chewing Rates In Horses, concluded:


The horse makes:

  • 800 – 1200 chewing movements /kg conc.
  • 3000 – 6000 “ “ /kg hay.

Chewing Rates

Oesophagus

A muscular tube, measuring 120 – 150cm long. Transports food material from the Pharynx down into the Stomach. Choke is the most common nutritional related problem associated with the Oesophagus. Joins the stomach via a strong muscular valve called the Cardiac Sphincter. By enlarge, this valve prevents vomiting.

Stomach

The equine stomach is relatively small, with a capacity of 9 – 13 litres. The digestive process starts in the mouth, some fermentation & digestive action begins to occur in the stomach. Food does not normally remain in the stomach for long periods, before passing into the small intestine.

Small Intestine

The horse has a relatively short small intestine. 21-25m (70ft) long in a 450kg animal. Consists of Duodenum, Jejumum & Ilium. Primary site of digestion & absorbtion of soluble Carbohydrates, Protein, Lipid, Vitamins & many Minerals.

  • Parasite control is essential for health.
  • Food passes through @ 1ft./1minute.
  • Food can pass through in 45 minutes.
  • Amylase activity only 5-6%

Large Intestine

The large intestine is also called The Hindgut.Consists of the Caecum, Large Colon, Small Colon & Rectum. 45ft long, but large volume. Holds 10x number of bacteria than cells in horses body. Digesta reaches hindgut around 3 hours after a meal, by which time all nutrients digestible by gut enzymes should be digested & absorbed. Food can remain 65 hrs, most forage digested here.

The bacteria that live in the large intestine, produce enzymes which digest fibre. The end product being volatile fatty acids (Acetate Proprionate & Butyrate) that are absorbed & used as energy sources. Bacteria also supply some H2O soluble vitamins, the diet of horses with high demands; such as rapid growth must contain essential amino acids & H2O soluble vitamins.

Nutrient Requirements

Water

Not strictly classified as a nutrient. Water is required in the largest amounts, making up 70% body mass. Many functions: Digestion, thermoregulation, metabolism & lubrication. Requirements depend on many factors, estimates vary from 20 – 60 litres per day.

Dehydration

One of the first signs of dehydration is reduced skin elasticity, which can be assessed by taking a pinch of skin at the base of the neck & measuring how long it takes to return to normal. In a fully hydrated horse this is instant, any delay of 1 or 2 seconds or more indicates dehydration.

Normal Muscle Sample
RER Equine Muscle Sample
EPSSM Muscle Sample

Energy

Energy is not classified as a nutrient, but is an essential derivative of feed nutrients.

  • Energy is a fuel which drives every bodily process.

Deficiency of energy can diminish; growth rate, reproductive performance, athletic performance, resistance to disease parasites or other stress & affects appearance of horse. Excess energy causes; obesity, laminitis, colic, reduced resistance to some diseases & skeletal problems.

Protein

Proteins are complex compounds made up of chains of amino acids. There are 20 amino acids found in food, of which 10 are known as Essential Amino Acids. These cannot be synthesised by the body & must be supplied in the diet. Protein makes up about 17 – 19% of the body & is in almost every cell.

Minerals

The horse requires at least 21 different minerals. Calcium, Phosphorus, Magnesium, Sodium, Chloride & Potassium are the Major Minerals because they are required in high amounts and make up about 4% of horses body. Trace Minerals are required in smaller amounts & are less important. Calcium is required for muscle function, blood clotting & bone development. Phosphorus is also involved in bone formation. Magnesium required for bone formation & for many enzymes. If blood levels of Magnesium greatly reduce, the animals develop “Tetany” (Muscle Spasm). Electrolytes (Potassium, Sodium & Chloride) important in osmotic pressure regulation & acid-base balance.

Vitamins

Vitamins are required by the body in relatively small amounts, but are absolutely essential for life & are involved in fundamental processes in the body. Deficiency results in disturbed body function & eventually disease. Vitamins are divided into two categories; Fat-soluble (A,E,D & K) & H2O soluble.

Formulating A Diet

Determine the horses bodyweight & condition.

Decide whether the horse is in appropriate condition or needs to either lose or gain weight. Investigate the horses nutritional requirements, which depend on his level of work, stage of life & reproductive status. Choose suitable forage & feed & calculate the amounts required to meet requirements for nutrients. Add vitamin & mineral supplements if necessary, and add other health promoting supplements if necessary.

Establishing Bodyweight & Condition

  • Weighbridge
  • Weightape
  • Measuring heart girth & length & calculate as below: Bodyweight (kg) = (heart girth x heart girth) x length divided by 11877

  • Condition Scoring

How Much To Feed?

  • Weigh/Weightape Animal
  • Feed 2.5% of body weight.e.g. 2.5% of 500kg (1100lbs)is 12.5% (27.5lbs)
  • Adjust quantity of feed to maintain weight.
  • Monitor weight & condition of animal
  • Feed By Scoop Weight Not By Volume

Always remember there is a considerable difference in density among feeds. Feed by weight not by volume.1 Plastic Round Scoop holds:

  • 2lbs ~ Mix
  • 3lbs ~ Cubes
  • 1lb ~ Chaff

  • Why Is Fibre Important?

    • Maintains Digestive Function.
    • Satisfies Appetite.
    • Provides Occupational Therapy.
    • Supplies Essential: Energy, Protein, Vitamins & Minerals.
    • Consequences of a low fibre diet result in: Digestive dysfunction – colic, stable vices & fewer droppings!

    Laminitis

    Call The Vet!

    Laminitis is a medical emergency & if suspected, a vet should be called without delay. Dietary causes of Laminitis:

    • Energy overload – sugars & Soluble carbohydrates. Mismanagement – large meals & overweight horses.
    • Concussion / weight Bearing
    • Toxic shock i.e. post colic, retained placenta
    • Diet Implicated
    • Hormonal
    • Iatrogenic i.e. Steroids

    Feed bulk roughage with a low feed value, such as straw. Reduce hay & bulk out with straw. Feed fibrous feeds when the horse is back in work, not cereals. Keep him in bare paddocks. Turn out on sand areas some of the time. Use a muzzle some of the time and treat metabolic disorders.

    Use electric fencing to restrict access to grass. Beg, borrow or buy sheep or cattle to keep the grass down. Increase workload before increasing feed.

    Use oil as an energy source.

    • Feed little & often, so you do not overload the stomach.
    • Do not “Starve” the animal.
    • Do not graze frosty grass – Fructans

    Hyperlipaemia

    Caused by an excess of blood lipids (fats) most often seen in horses with reduced/no food intake. As a result, leads to breakdown of adipose tissue leading to a build up of an excessive amount of lipid in the blood.

    Clinical signs:

    • inappetence
    • depression
    • weakness
    • muscle fasiculation(involuntary twitching) ataxia.

    Prognosis poor.

    Can be avoided by ensuring horse/pony has adequate food intake.

    Fat mobilisation increased when horse deprived of food.

    • High plasma triglyceride.
    • Prognosis poor.

    Hyperlipaemia Prevention

    Consider nutritional support carefully.

    • Feed absolute minimum 1% bodyweight per day of hay (or alternative).
    • Balance micro-nutrients.
    • Educate the owner.
    • Don’t use words “starve” or “protein”.
    • Consider nutritional support in acute cases.
    • Minimise soluble carbohydrates & recommend high fibre diet.

    Colic

    There is a much higher incidence of colic in horses than other domestic animals, because of the complicated structure of the intestine.

    Colic is a general term given to abdominal pain, caused by a variety of different conditions.

    • 1) Spasmodic Colic (spasm of muscular wall of intestine)
    • 2) Impactive Colic (impaction of food material in large intestine, most frequently in large colon)
    • 3) Gaseous Distension Of Intestines
    • 4) Twisted Gut (twisting of intestines or rotation of intestine about its mesentary)

    Clinical Signs Of Colic

    Dietary Causes Of Colic

    • Indigestible High Fibre Feeds
    • Lack Of Water
    • Energy Overload
    • Change Of Diet

    The Horse is designed to eat:

    • Frequent, small meals of high fibre ingredients.
    • Digested primarily by bacteria in the hindgut.
    • Make all feed changes gradually.
    • Do not exercise immediately after feeding.
    • Feed plenty of roughage.
    • Fresh clean water available at all times

    In the words of Capt Horace Hayes FRCVS “The eye of the master remains important in feeding of the horse. Fortunately the master also has more scientific help at his disposal than ever before…….”