Equine Husbandry

Original Editor - Ansi van der Walt Top Contributors - Jess Bell, Kim Jackson, Tarina van der Stockt and Chelsea Mclene

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Equine Behaviour

Horses are preferential grazers and, in the wild, have adapted to live life on open plains or mountains. They are, however, adaptable to environmental challenges and can live in other areas. Studying feral or free-ranging horses provides insight into the behaviour of domestic horses today. In particular, it highlights that most adaptive equine behaviours have not changed significantly in 6000 years of domestication.

Horses typically live in herds and the behaviour of each horse helps to achieve stability within the group. Being a member of a group is essential to the horse's survival in the wild, so members of a herd behave in such a way as to minimise inter-group conflict. The following features are typical of a herd that has a stable social structure:

• There is conflict avoidance
• Hierarchical relationships are not regularly reinforced
• Aggression is commonly related to competition for limited resources (this is more pronounced in domestic horses compared to feral horses)
• Changes in herd membership causes instability

Equine Communication

Horses communicate mostly through visual communication, although they do engage in some vocal communication. as well as using odour and touch. Horses are very sensitive to the body language of other horses - they also generalise their communication to humans as well and are able to react to changes in our body language. They are, therefore, responsive to human stress signals. While horses are usually perceived as a "social prey species" whose survival depends on fleeing from predators, horses may respond to predators with defensive behaviour when flight is not an option. They will communicate their response to threats in the following ways.

Aggressive threat signals in horses:

• Initially, horses provide subtle signals such as nose wrinkling and ear flattening
• These signals escalate to head jerks, baring teeth, stomping a front leg, charging, and ultimately biting
• Direct attacks might appear to come out of nowhere, but they are actually often a learnt response to people who do not respond to the horse's more subtle threat signals

Defensive threat signals in horses:

• Also begin with mild signs like nose wrinkling and ear flattening. This may provide the horse the opportunity to decide if it should respond defensively or aggressively
• These signs progress to body blocking movements, flattening its tail and presenting its rump, raising a hind leg, backing up and, finally, kicking with the hind leg

Feeding

Food and fodder placement can have a significant impact on a horse's physical health. The following table provides a summary of the benefits and disadvantages of types of food and fodder placement.

	Advantages	Disadvantages
Hay net	Only a small amount of waste	Forces horse into an unnatural head and neck position when it is placed too high Horse's foot might get stuck if it is too low Horse is at risk of upper respiratory tract irritation from dust and seeds
Hay bag	Only a small amount of waste	Forces horse into an unnatural head and neck position
Ground	Natural spine position	High amount of waste Risk of sand colic
Haybar	Natural spine position	Only a small amount of waste

Equine Body Condition Scoring

Using the equine body condition scoring system gives an indication of a horse's overall health. This system was described in 1983 by Henneke and colleagues. The full scoring system is provided here. The following video provides examples of horses being scored.

Basics of Equine Nutrition

The equine digestive tract consists of the following features:

Type	Fore Gut	Capacity	Percentage of gastrointestinal tract
Enzymatic digestion	Stomach	8 – 15 litres	8%
	Duodenum, Jejenum, Ileum  (21 metres)	68 litres	30%
	Hind Gut
Microbial digestion	Caecum (1.2 metres) Large colon (3 – 3.6 metres) Small Colon (3 – 3.6 metres)	28 – 36 litres 86 litres 16 litres	15% 38% 9%

The following video provides a summary of the equine digestive system.

Horses are non-ruminant herbivores (i.e. hind-gut fermentors) and typically spend around 16 hours a day grazing.

It is important to note that the equine stomach is not designed to process large volumes of food. Horses have a small stomach, with limited feed intake capacity. Any horse who is being given large volumes of hard feed (i.e. grains) needs to be referred to a veterinarian or equine nutritionist. The stomach initiates the breakdown of food by secreting hydrochloric acid and pepsin.

Because horses do not have a gall bladder, it is difficult for them to digest high fat diets. Thus, a normal equine diet will only contain around three to four percent fat.

Most digestion of nutrients, and absorption of vitamins and minerals occur in the horse’s small intestine.

The caecum (beginning of the large intestine) has various functions:

• Liquids mostly pass through to here
• Detoxification of toxic substances
• Contains protozoa and bacteria that digest fibre and soluble carbohydrates in the small intestine

The large intestine (large colon, small colon, and rectum) has four parts:

• Right ventral colon
• Sternal flexure to left ventral colon
• Pelvic flexure to left dorsal colon
• Diaphragmatic flexure to the right dorsal colon

Impaction is common in the sternal and diaphragmatic flexures.

Water

Water is the most important nutrient in a horse’s diet. Signs of a lack of water include:

• Decreased intake of food and physical activity
• Typical signs of dehydration such as:
  • Dry mucous membranes in the mouth
  • Dry faeces
  • Decreased capillary refill time

Water deficiency may be due to a general lack of a water source, low water palatability, or accessibility (if it is frozen or contaminated) or illness.

Energy

Energy is not a specific nutrient, but it is necessary for life. Signs of energy deficiency in horses include weight loss, decreased physical activity, milk production and growth rate. However, horses who take in too much energy, may become obese and are at greater risk of colic and laminitis. They also experience more sweat loss and decreased exercise tolerance.

Fat

Fat contains three-times more energy than grains or carbohydrate sources, so when it is added to feed, greater energy is available for the horse. Most premixed feeds usually contain 2 to 6 percent fat, but this can be as high as 10 to 12 percent fat.

Carbohydrates

Carbohydrates are the main energy source most equine feeds. Horses easily break down and absorb soluble carbohydrates such as starches and sugars to glucose in the small intestine. Insoluble carbohydrates such as fibre (cellulose) are fermented by microbes in the large intestine, which produces energy in the form of volatile fatty acids.

Soluble carbohydrates are present in most types of horse feed, but volumes are largest in corn, followed by barley and oats. Forages typically contain 6 to 8 percent starch, but some may be up to 30 percent starch. It should be noted that the sudden consumption of large amounts of starch / sugar can lead to colic or laminitis.

Protein

Protein is essential for muscle development, either during growth or exercise. Amino acids are the main building blocks of protein. Adult horses typically require 8 to 10 percent protein in their diet, but lactating mares and foals will require more.

Signs of protein deficiency in horses include:

• Rough or coarse hair
• Weight loss / reduced growth
• Decreased milk production
• Reduced performance

Conversely, ecess protein can cause:

• Increased water intake and urination
• Increased sweat loss during exercise (leading to dehydration and electrolyte imbalances)

Vitamins

Vitamins are either fat-soluble (vitamin A, D, E, and K) or water-soluble (vitamin C, and B-complex). Horses usually receive adequate levels of vitamin in a deit that includes fresh green forage and / or premixed rations. However, supplements may be needed if horses are:

• Receiving high-grain diets
• Receiving low-quality hay
• Stressed (e.g. travelling, showing, racing)
• Involved in prolonged strenuous activity
• Not eating well (due to illness etc)

Minerals

Minerals are necessary for:

• Body structure
• Fluid balance in cells (electrolytes)
• Nerve conduction
• Muscle contraction

Horses only require small amounts of the macro-minerals (e.g. calcium, phosphorus, sodium, potassium, chloride, magnesium, and sulfur) daily.

The following table summarises the role of specific minerals:

Role	Mineral
Fertility	P, Cu, Zn, Se, Mn
Bone development	Ca, P, Mg, Mn, Cu
Muscle development	P, S, Zn, Se
Milk production	Ca, P, Mg, Zn
Skin and claw health	Zn, Cu, Mn
Hair coat	Cu, Zn, Se
Disease resistance	Cu, Zn, Mn, Se
Foetal development	Cu, Zn, Mn, Se
Nervous system	Mg, P, Cu
Appetite	Mg, K, Zn, Cu

Stable Floors and Bedding

Horses often spend a significant amount of time in their stalls, so specific aspects of flooring should be considered, including:

• Shock absorbing qualities in order to reduce stress on the horse's joints when it moves or gets up from lying down
• If it is non-slip in order to reduce the risk of a horse injuring itself when it gets up
• If it is hard wearing so that it remains level, thus reducing the risk of a horse developing postural strain syndromes

The following table, adapted from Fabian, assesses a number of flooring materials for the above qualities.

	Shock absorption	Non-slip	Hard wearing
Topsoil	Good	Good	Poor
Clay	Good	Good	Poor
Sand	Good	Good	Poor
Concrete	Poor	Variable	Good
Asphalt	Poor	Variable	Good
Rubber mats	Good	Good	Good
Grid mats	Good	Good	Good
Wood	Good	Poor	Good

Turnout (Paddock Time)

Turnout or free exercise time has been found to have positive effects on horses' behaviour. The following table summarises some of the advantages and disadvantages of different durations of turnout time and sizes of paddock:

	Advantages	Disadvantages
Size of paddock
Small	Less risk of injury	Less free movement, which affects: Digestion Circulation Musculoskeletal mobility
Large	Encourages constant movement	May increase injury risk
Separated from other horses	Reduces risk of injury	Psychological isolation may increase stress Low stimulus for movement
Amount of turnout time
Restricted	Reduced risk of injury	May increase stress Low stimulus for movement
Most of the day	Encourages free movement	May increase injury risk

Reducing Stress in Horses

Stress has been found to have an impact on farm animals’ growth, production, reproduction and susceptibility to disease. Chronic exposure to stress and the associated ongoing release of cortisol negatively impacts immunity, digestion, behaviour, reproduction and the cardiovascular system. Similarly, animals may develop gastric ulcers, colic, and diarrhea when exposed to stress. The following factors can increase stress in horses.

Improper feeding

In the wild, horses move and graze. In fact, feral horses spend 70 percent of their time grazing. If a horse is not on pasture, it is recommended that they be fed at least four times a day at regular intervals. If high energy feeds are given inappropriately, in some cases this can increase stress.

Lack of exercise

Resting without any exercise can increase stress levels in horses.

Isolation

Horses are herd animals. Herds help to provide security, status, entertainment and emotional support. Horses physical and behavioural needs are best met when they live in groups, but a number of horses still have limited / no physical contact to other horses.

NB companion animals do not have to be horses - other animals they could be housed with include donkeys, goats and llamas.

Boredom

Boredom can cause stress in horses. Providing toys can help to address common stress related behaviors such as cribbing and weaving. The use of mirrors can be beneficial for horses confined in their stalls. Moreover, when travelling, it has been found that the use of a mirror is preferable to travelling alone, but a live companion is still recommended when possible.

Lack of Confidence

A confident horse is better able to cope with stress. New sights, sounds and smells should be gradually introduced.

Contagious Stress

It is beneficial to speak to your horse in calming tones and that you remain relaxed. If your horse becomes stressed, it is important to control your own reactive stress.