13 May 2008
HORSE Website
HORSE Magazine
Counting calories
Do you know which feed types are high and low energy, and the affect of calories in your horse’s diet? Teresa Hollands explains
Teresa originally specialised in human nutrition and biochemistry as part of her first degree, followed by two post graduate qualifications specialising in animal and equine nutrition. She has been working as a nutritionist for nearly 20 years and is responsible for Dodson and Horrell’s research programme.
Spring is fast upon us and the grass is growing. The aim of all responsible horse owners at this and every other time of year must be to ensure that their horse remains fit not fat. It is vitally important that as horse owners we understand the responsibility we have to our horses in terms of ensuring that they do not get too fat and we should extend the same courtesy to ourselves. Many of the nutrition principles applied to horses share a common theme with human nutrition, although of course there are some fundamental differences.
1) Understand calories
Anything and everything you feed your horse provides him with calories/energy. The two words are interchangeable and are measured as megajoules of digestible energy per kilogramme (MJ DE/kg) in horses and calories (kcals) in ourselves. If too much energy is being provided, you or your horse will put weight on. If you are not providing enough energy, weight loss will occur; if you get it about right, then weight stays constant. All food provides energy, however some feeds will provide energy faster than others.
Which feeds are high or low in calories?
Facts about oil (a supply of fatty acids)
- Fat is not a natural ingredient in the diet of a wild horse, and grass contains only about 2 percent oil.
- Fat provides more energy per kilogram than any other ingredient used in horse feeds.
- High oil feeds should not be fed to horses prone to weight gain.
- Some fats are very high in omega 3 fatty acids, for example linseed and cod liver. Grass also contains a good ratio of omega3 : omega6 fatty acids, but hay is very low in these essential fatty acids.
- Oil is digested in the small intestine very efficiently by the horse, especially considering that he does not have a gall bladder. However, because of the way horses and humans ‘burn’ fat as an energy source in the cells of our bodies, oil is considered a slow releasing source of energy.
- Racehorses are unlikely to need much fat in their diet as they need fast-releasing energy supplies.
Facts about fibre (a supply of structural carbohydrate)
- Horses evolved to survive by eating fibre and thus their hind gut is adapted to breaking down large quantities of fibre because of the huge numbers of bacteria which live there.
- Your horse cannot actually digest the fibre himself; bacteria digests the fibre and then the horse absorbs the by-products of the bacterial breakdown. These by-products are in turn incorporated and used in the biochemical energy cycles to produce glucose. This takes a long time, so fibre is a slow-releasing energy source. Generally speaking most fibres (except alfalfa and sugar beet) are low in energy.
Facts about starch (a supply of storage carbohydrate)
- Starch is the storage energy of plants found in seed heads of all mature grasses and seeds of cultivated oats and wheat. While a horse can eat large amounts of starch, it is vitally important that the total amount is fed in small meals so that as much starch as possible is broken down to glucose in the small intestine.
- Undigested starch in the hind gut is dangerous.
- It is possible to measure the amount of glucose coming from the starch by measuring the glycaemic response of the food. The glycaemic response is a measure of the amount of glucose appearing in the bloodstream after a meal of starch. A food with a high glycaemic response, (nearly all the starch is broken down to glucose) means little or no undigested starch reaches the hind gut.
- Starch is broken down quickly by enzymes in the small intestine and is considered medium energy, but fast releasing.
2) Calories do not change a horse’s character
Food, per se, cannot change a horse’s character; however you could exaggerate the natural metabolism/character of your horse by feeding the wrong type of energy. If you feed a naturally excitable Thoroughbred lots of fast-releasing energy, keep him stabled and don’t exercise him enough, he will become more manic. A laid back horse fed too much energy will simply get fat and then become lazier. When you are feeding energy you have to consider:
• Type and amount of energy given
• Horses need bulk and must eat 2.5 percent of their bodyweight in feed
• The foundation of all diets should be fibre
3) Monitoring calorie intake
Because weight gain or weight loss can be very gradual, it is important that you monitor your horse regularly, so you pick up the changes before your eye sees them.
Weigh your horse
Weigh your horse fortnightly with a weightape, always at the same time of day, and note the weight down. If you see an increase in centimetres or weight over a month, you need to decrease the calories, (but not the bulk) you are feeding.
Weigh feeds
The energy requirements of horses are based on averages; your horse may maintain weight on less calories than your friend’s horse. It is therefore important to weigh the food your horse is eating, (including the hay/haylage) every time you change his diet. A nutritionist can then work out the amount of energy he is eating and help you adjust his diet. It is advisable to find containers which hold exactly the quantity of food recommended rather than trying to guess ‘half a scoop’.
Condition score your horse
Condition scoring is a measure of fat cover only. Feel areas where weight gain is likely, such as the crest, neck, ribs and quarters and give a score between one and five. (One would be very thin and five would be obese). You can only decide if your horse needs to lose weight by monitoring his fat; if he is over a condition score of three and you cannot feel his ribs then he needs to lose weight gradually. But the weight loss plan needs to start today. Condition score the horse every time you weigh him.
Teresa’s top tips
- Calories (energy) are provided by all feeds. Forage feeds, (high fibre) tend to be the lowest in calories; oil and starch-based feeds tend to be highest in energy. A small amount of a high-energy feed or a larger amount of a low-energy feed can provide the same amount of calories.
- Remember not to forget the nutritional contribution of hay, grass and haylage.
- Because the horse is a trickle feeder, food provides more than calories - the horse has a psychological need to chew.
- If your horse needs to lose weight, cut back on calories not bulk.
- Hay soaked for 12 hours loses most of its energy, meaning you can feed more of it; just remember to top up the protein and vitamin and mineral levels in the diet.
- Choose feeds formulated for your horse’s workload (call a feed manufacturer’s helpline if you are unsure) and monitor his weight.
Obese horses of welfare concern
Recently Tony Tyler, director of UK operations for the ILPH, expressed his concern that the charity is seeing more and more cases of obese horses and ponies. He pointed out that having horses or ponies with a condition score of five is considered as much of a welfare issue as having one with a condition score of one. (See ‘Condition score horse’, below.)
Why worry about our horses being too well covered?
All horses should be condition score three or less, or they will be at risk from:
- Increased risk of laminitis
- Decreased performance/life span
- Increased strain on heart, lungs, legs and feet
- Increased risk of developmental problems in growing youngstock
- Possible link to cushings
- Overweight mares are likely to produce overweight foals
Fat facts
- Fat is not muscle and cannot be changed into muscle
- Fat is an insulator - muscle has a specific role of movement
- Fat hides muscle definition
- Muscles which are not used become small and useless
- Exercise results in topline, not feed
Case study
It is important to feed the right the right sort of energy and tailor the diet to the horse; in this example, a fizzy Thoroughbred requires a slow-release, yet high-energy diet.
Deluxe is rising four. He is a 17.1hh dressage horse ridden by Damien Hallam. Damien describes Deluxe as “a horse that just loves life; his sheer exuberance will be fantastic for his future career as a top dressage horse, but at the moment it is a little difficult to control.’ Although his workload involves quiet strengthening work, just walking and trotting, and no competitions, he needs a lot of energy (calories) in his diet, because he burns so much off just simply being him.”
Deluxe’s diet
- 12kg hay (green colour)
- 2.5kg high fibre, high oil, low starch mix (blue, green and red)
- 250ml soya oil (blue)
- 1.5kg alfalfa chaff (Green)
- Deluxe is getting 78% of his energy from fibre, 9% from oil and 11% from starch
Total calories from this diet =144MJ of DE, (normal requirements are 103.5 MJ), therefore Deluxe needs 30% more energy than an ‘average’ horse of his bodyweight in light work.
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