Feeding An Off The Track Thoroughbred

By Dr Carly Garling

A Thoroughbred that has just finished its racing career or come directly from a spelling farm will have very different nutritional requirements to a Thoroughbred who has never raced or spent minimal time in race training. This is due to the diet they are fed whilst in training and spelling.

When assuming responsibility for a recently retired racehorse, it is important to be aware of what they have been fed previously, so their nutritional needs can continue to be met as they “let down” and transition to their new life with you as their partner.

Most horses in training will have received a very high amount of concentrate in their diet (hard feed in the form of grain, such as oats/corn/barley). This high concentrate feed will have allowed them to obtain enough energy during their racing careers to encourage muscle growth/development and support body condition.

However, to understand a little about how this is relevant to you as their new owner, you need to have a basic understanding of the horse’s gastrointestinal system (stomach and intestines) and how they function.

As the horse has evolved to be a grazer/forager in the wild, it has been designed with a large hindgut (caecum) which acts as a fermentation chamber in order to produce energy. This means for a horse to stay healthy it needs forage (such as grass/hay) for the hindgut to ferment 24hours a day. This will lead to a fine balance of microflora in the hindgut, which is capable of breaking down forage and providing energy and vitamins/minerals to the horse.

Once we ask the horse to undergo more rigorous exercise, whether this be dressage/showjumping/racing/eventing, the horse will need greater support in the form of energy. This will be mostly supplied by people in the form of grain (starch).

A small amount of starch (no more than 2g starch/kg of horse bodyweight e.g. no more than 1kg in one meal for a 500kg horse) can be tolerated by the horse, as it is broken down in the horse’s foregut. However, once your feeding surpasses the recommendations, the undigested starch will move into the horse’s hindgut (fermentation chamber). Once the starch enters the caecum it will undergo rapid fermentation which results in pH shift to acidic, as well as favouring bacteria that are less able to break down fibre (such as grass/hay).

If your horse’s hindgut becomes acidic, it predisposes them to many diseases which may start to manifest clinically and affect their ability to be healthy and perform at their best for you. These diseases include colic, diarrhoea, laminitis, and the ability to absorb essential vitamins/nutrients, manifesting as poor hooves and a dull coat, as well as inability to retain condition.

This is relevant to you as your horse is likely to have finished his career with a diet high in grain and a gut microflora. They will need support to transition back to a forage-based diet whilst obtaining sufficient energy from feed and sufficient vitamins/minerals to be healthy.

With this overview of how a horse’s gastrointestinal system works, here are some tips to support your new best friend through the “let down”:

1. If your horse is underweight, this simply means that the energy (calorie) intake is lower than the horse’s needs. Simply, they need more feed.
2. Know what you are feeding them – amounts of hay and hard feed (concentrate) need to be accurately weighed using a set of scales. “A dipper” of feed is not an accurate measurement.
3. If horses are kept in intensive conditions such as stables or yards with little to no grass, their conditions need to mimic patterns of a grazing animal:
   • Continuous feeding pattern, where forage makes up bulk of the diet (such as hay). All horses should receive a daily intake of 1.5% of body weight per day with good quality hay or equivalent (grass). This equates to 7.5kg of hay per day for a 500kg horse.
   • Three times daily feeding rather than twice daily, smaller concentrate meals throughout the day.
   • For a 500kg horse, grain or concentrate meals should be no more than 2.5kg to reduce the risk of hindgut disturbances (hindgut acidosis). 
   • Extending eating time by diluting the energy density of the meal with chaff or feeding forage before grain.
   • If horses are gorging food, place large stones in the feeder trough, so they need to eat around these.
4. Adequate forage and fibre:
   • Some people believe that feeding large amounts of concentrates to their horse is beneficial (similar to feeding a dog or a cat), however feeding more hay than concentrate will reduce abdominal problems such as hindgut acidosis, colic and gastric ulcers.
   • Fibre can also be increased by other sources such as sugar beet pulp or soya hulls, decreasing reliance on grain or sweet feed for energy.
   • Forage quality – feeding straw that is poorly degraded may increase the risk of impaction colic. Horses should never be fed mouldy forage.
5. An off the track Thoroughbred will need to be fed concentrate as well as hay:
   • This is because it has come off a high grain diet and the hindgut will need time to transition from a grain dependency (bacterial flora which breaks down grain) to a forage-based diet with associated microflora.
   • During this time supplement your horse with a feed that has a mix of grain, other energy/fat sources such as beet pulp, soya hulls, oils (corn, soy, safflower, flaxseed), other sources of fat (stabilised rice bran), with the aim to reduce grain feed, and with enough vitamins and minerals to support overall health, such as hoof growth/regeneration.
   • Regularly assess your horse’s body condition and increase or decrease feed accordingly.
6. Feed to reduce your horse’s risk of colic:
   • Studies have shown that sudden change in feed will increase your horse’s risk of colic (you need to transition diet and batches of hay over a two-week period).
   • feeding high levels of concentrate >2.5kg in one feed, will increase your horse’s chance of colic.
   • feed your horse small meals more frequently.
   • High concentrate and low forage diets have been implicated in the development of gastric ulcers (which may display colic signs).
7. Other considerations to help your off the track Thoroughbred:
   • Paddock mates – your horse may not be very good at guarding their food as they may be adjusting to his new environment. Feed them separately so you know they are getting all the food they need and aren’t having to fight for their meal.
   • If your horse has come off the track clipped or has been used to a stable, then mindfully rugging your horse in cold, wet and windy conditions will support them.
8. Veterinary considerations:
   • Make sure your horse has had a faecal egg count to check his worm burden, and that his teeth have been examined by a vet under sedation and with a light source in the last 12months.
   • If your horse is not gaining weight and is showing other signs such as having a dull coat, irritability, dropping feed, not interested in eating or diarrhoea, you should contact your veterinarian as they may have a condition that requires treatment.

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