The racing diet
In order to meet the extreme physical demands of racing, racehorses are usually fed a scientifically calculated diet which includes high quantities of concentrates. “Your average three-year-old is on a 14% protein concentrate, with a very high energy content,” explains racehorse trainer Ashleigh Hughes, who is in a training partnership with John Vos at Turffontein Racecourse.
Generally, the horses start the day with a small pre-work meal of up to 1kg. They will then receive a morning meal of 3-5kg of concentrates, and may have another small feed early afternoon. Supper is probably 4-6kg of concentrates. Although racehorses do have unlimited access to hay, and lucerne is also fed, concentrates are prioritised in order to optimise their performance on the track.
While this is far removed from the grazing they enjoyed as youngsters on the stud farm, Thoroughbreds adapt, becoming ultra-fit, tuned athletes on their racing rations. However, in the process, they may lose some of the ability to digest forage.
Results of high concentrate feeding
Australian nutritionist Dr Nerida Richards, the resident nutritionist at Feedxl.com, explains that a Thoroughbred who’s adapted to processing 8kg or more of concentrates a day may have the following problems when he comes off the track:
Bacterial imbalance in the hindgut
The horse’s hindgut contains two main families of bacteria, those that ferment fibre and those that ferment starch and sugars. When a high-concentrate diet is fed, the starch or sugar bacteria may start to predominate. These bacteria create a more acidic gut environment, causing a condition known as hindgut acidosis. At this pH level, the fibre-fermenting bacteria cannot function well and they start to die off. So even if your OTTB eats up his hay or lucerne, he might not be able to get much goodness out of it.
Every horse is different. Some have more ability to digest starches than others, but any horse on a high-concentrate diet will be at risk for developing acidosis, and even horses with subclinical acidosis have a greater risk of colic as well as laminitis.
It’s estimated that up to 90% of racehorses in training have ulcers. “Gastric ulcers cause many problems but perhaps the two most relevant in the situation of feeding an OTTB are loss of appetite and weight loss,” Richards says.
OTTBs sometimes have shelly, weak, slow-growing hooves. Richards believes that a lack of biotin is the major cause, because the imbalance of bacteria in the hindgut causes them to become biotin-deficient.
This can be due to gastric ulcers, or due to a vitamin B1 deficiency caused by the high-concentrate diet.
Continuing on high concentrates
Thoroughbreds come off the track with a high percentage of muscle and very little fat. As soon as they start losing muscle, they appear thin. A concerned owner might respond by upping the concentrates, and then upping them again, but over the long term this won’t solve the problem. You’ll end up with a hot, fizzy horse who will still be a hard keeper and expensive to feed, with a higher risk of colic, and who may be very ‘footy’ if he loses a shoe.
Changing diet and rebalancing digestion
“The first critical step in getting a Thoroughbred back to normal is to restore the balance of bacteria in the hindgut, and get fibre digestion working properly again,” Richards says. The quickest way to do this is to cut concentrates out entirely, although you can also taper them off over a month or two. Whichever way you do it, your aim should be to switch the horse to a low-concentrate, high-forage diet. This can include:
- Ad-lib good-quality hay.
- Lucerne (4-5kg/day if needed for the first couple of months, cutting down to about 2kg/day long-term).
- Feed balancer or a vitamin-mineral supplement (fed in recommended quantities).
- Brewer’s yeast (up to 80g/day assists with hindgut health and fibre digestion).
- Biotin (20g/day assists with hoof health).
- Vitamin B complex (10g/day for picky eaters).
- High-fibre and high-oil alternatives such as beet pulp, copra, linseed oil, canola oil or crushed linseed can be phased into the diet if necessary.
- Little or no concentrates – if any concentrates are fed, you should choose low-starch ‘leisure’ concentrates rather than ‘performance’ concentrates.
To ensure that the diet is correctly balanced, you can either consult a nutritionist or use the diet balancing website Feedxl.com, currently available for free in South Africa.
Time and patience
By switching the diet to high-forage, low-concentrates, you will starve out the starch/sugar-digesting bacteria, and allow the fibre-fermenting bacteria to repopulate. This rehabilitation will take a few months, because the fibre-fermenting bacteria are very slow to reproduce. You won’t get instant results, and you might find your horse stays in ‘racing condition’ for a while before he starts looking fat. However, it really is worth the time and effort, as you will end up with a very healthy horse who holds his weight on a mostly forage diet.
The full article appears in the September issue of HQ (114)
Text: Jassy Mackenzie