Wednesday, 17 April 2013

Horse Nutrition: Basic Concepts



Hi :) In today’s post, we’ll take a look at the basic concepts of horse nutrition including some feeding guidelines, how to estimate bodyweight, feeding for maintenance, condition scoring, as well as developmental orthopaedic disorders and water requirements. If you have any questions, please don’t hesitate to let me know in the comments section at the end of the post. 

Basic Feeding Guidelines

There are several important rules, or guidelines, about horse nutrition and management that would be wise to follow when designing rations and feeding horses. These are listed below:


  • When pasture can’t provide the horse with enough nutrition, supplementary feeding should be provided to prevent the horse from losing condition. 
  • It is also important to ensure that the horse receives adequate roughage in order to maintain healthy gut function, particularly when the horse nutritional requirements aren’t met by pasture. The amount of roughage provided each day should be at least one per cent of the horse’s bodyweight. 
  • Changes in the ration should be made gradually: 3-5 days for a minor change and 10-14 days for a new feed. 
  • Feed little and often. This is because the GIT of a horse is adapted for grazing roughages (this is what a horse would do if it was in the wild). Horses and ponies should not go without feed for more than 12 hours – this predisposes them to hyperlipaemia. 
  • Horses should be given a quiet, non-interrupted time to eat, they also appreciate being fed at the same time and in the same place each day. 
  • Horses with special dietary needs may need to be fed separately to the other horses to make sure they are eating the correct amount of ration and to avoid bullying. 
  • Avoid strenuous exercise after a large feed. Only feed a small quantity of hay before strenuous exercise. 
  • Horses in training should be fed concentrates in proportion to the amount of exercise they have done on the day. 
  • Supplementary feed should be given in a trough, bin or tub to avoid the ingestion of sand and parasites and wastage. 
  • Horses should be fed below chest level to ensure adequate drainage from the airways and to prevent respiratory disorders. 
  •  Dampening feed reduces dust which lowers the risk of developing respiratory disease. 
  •  Avoid toxic feeds and plants (eg lawn clippings, ruminant and poultry feeds, mouldy feed, and feed contaminated with animal droppings. 
  •  Ensure that horses have access to clean drinking water at all times 
  •  Regular dental care and monitoring promotes efficient digestion of feed and nutrient utilisation. 
  •   Parasite control and managing or preventing sand accumulation also increases feed efficiency.

Estimating Body Weight


It is important to know the body weight of a horse so that you can design a ration that suits its energy and nutrient requirements. There are several methods that can be used to estimate the bodyweight of a horse. You could way the horse on scales, but this is only useful if the property that the horse is kept on has an appropriate scale. You can also make an estimate based on height and condition score. Alternatively you could measure the girth of the horse using a weight tape. Another option is to use the following formula:

            Weight (kg) = (girth2 x length)/1187

This formula is only a guide, however, as fit and lean horse tend to be lighter than the estimate while pregnant horses and those with a large gut fill tend to be heavier than estimated.

Condition Scoring

In Australia a condition scoring scale of 0-5 is used in horses.
0: Very Poor: very sunken rump, deep cavity under tail, skin tight over bones, very                    prominent backbone and pelvis.
1: Poor: sunken rump, cavity under tail, ribs easily visible, prominent backbone.
2: Moderate: flat rump either side of backbones, ribs just visible, backbone well covered.
3: Good: rounded rump, ribs just covered but easily felt
4: Fat: rump well rounded, gutter along back, ribs and pelvis hard to feel
5: Very Fat: very bulging rump, deep gutter along back, ribs buried.

Factors Affecting Nutritional Requirements

Quite a few factors determine the nutritional requirements of a horse. Size is one factor, a bigger animal would require more energy and other nutrients. The age and growth of the horse also affects requirements because a younger horse is likely to grow faster and need more energy and protein than an older horse. Energy requirements also increase with the intensity, duration and frequency of exercise. Pregnancy and lactation also increases requirements as well as the horse’s environment (eg temperature extremes) and the way it is managed (eg is kept in stables or in a paddock?).

Maintenance Requirements

Energy

Horses require approximately 13-15 MJ DE/100kg but this may vary among individuals. This energy is used for metabolic processes, maintaining body condition and thermoregulations and for exercise to gather food and for voluntary activity.


Protein 


130-15 grams of crude protein/100kg of bodyweight is required. This may be able to be supplied by the pasture but this depends on the quantity and quality of the pasture. Horses also require essential amino acids to be supplied in their diets as they are monogastrics. For most horses, protein requirements aren’t an issue. However, protein becomes more important in young, growing horses and in pregnant mares.

Fibre

Horses must be supplied with fibre that weighs at least 1% of their bodyweight. In addition the overall daily intake of food needs to have enough bulk so that the horses spend lots of time eating in order to prevent boredom.

Working horses, pregnant and lactating mares and growing mares will require more protein and energy than that needed for maintenance. The intensity and duration of the work will affect the requirements of working horses. These horses will also require a good supply of sodium, potassium, magnesium and calcium ions as these are lost in sweat during strenuous exercise.

Pregnant mares require good body condition in order to optimise fertility and as a result should be on a rising plane of nutrition at mating. It is also helpful to avoid weight loss during the first three months of gestation as this is when the embryo implants in the uterus and organs begin to develop.


Developmental Orthopaedic Disorders

Developmental orthopaedic disorders are a group of musculoskeletal abnormalities that occur in growing horses. Examples of these disorders include osteochondrosis, physitis (enlarged growth plates), malformation of cervical vertebrae and juvenile arthritis.

Horses tend to have a genetic predisposition for these disorders but other factors can increase the risk of developing them too. These include a rapid or irregular growth rate, an excess of energy in the diet, calcium and phosphorus deficiency or an imbalanced Ca:P. Copper and zinc deficiencies can also increase the chance of developing the disorders. A lack of or excess of exercise, particularly on hard ground, may have a similar effect too.

In order to reduce the risk in young horses, a lean body condition score should be maintained. In addition, steady growth should be promoted and the horse should receive an adequate supply of energy in its diet. Horse should also receive preferably between 12 and 24 hours of free exercise a day. However, excessive exercise should be avoided in susceptible individuals. 

Adequate calcium and phosphorus should also be provided to maintain a Ca:P of 1.2:1 – 2:1. Copper, zinc, magnesium, manganese and selenium should also be provided in appropriate amounts. Vitamins A, D and E must also be supplied.

Water Requirements

In mild conditions, horses require 4-5L of water per 100kg of bodyweight. However, dry feeds will increase the water requirement and at least 50L of water should be available in hot weather. Humidity, exercise, reproduction and lactation, growth and losses through the gut and urine will also increase water requirements.



That’s all for now, see you next time :)

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