ISSUES OF MATURE RACEHORSES AND COMBATING THEM THROUGH CORRECT FEEDING
There are a number of potential digestive health problems that can occur in racehorses that can be related to feeding and for the purposes of this article I have chosen to write about some of the most common ones that we may encounter at least once in during our times of owning a racehorse!
Equine colic is loosely defined as abdominal pain and the causes are numerous. The signs of discomfort (rolling, kicking, pawing and sweating) will be familiar to most experienced horse handlers. Colic is one of the most common health emergencies and is a leading reason for surgery in horses.
Years of research have been devoted to sorting out management practices associated with causes of colic. Careful examination has led to some general conclusions about factors that may put horses at increased risk. Below is a summary of trends identified by several independent studies.
Some studies identified Thoroughbreds, Arabs and Warmbloods as having more frequent colic’s than other breeds, while other studies found the opposite was true. There are no proven trends.
There is some evidence that more colic’s occur in horses between the ages of two and ten.
These are the years of heavy training and performance. Horses maybe under stress from frequent travel, competitions and changes in schedule. Look and management, training and feeding regimes to help reduce high stress levels
One study showed that eventers had a higher risk of colic compared to other sports horses, whereas other studies have shown that race horses would have the highest incidence.
Racehorses and competition horses are more likely to face disruption to feeding and management routines during the racing and competition season. Racehorses consume huge amount of concentrate feed with little forage, increasing the risk of hindgut acidosis and colic.
Pasture Vs Stable:
Horses that were at pasture for 24 hours a day have low rates of colic and the risk increases with the time spent in a stable.
Racehorses may get less exercise, eat less fresh forage, and be under increased stress from boredom and lack of companionship. Look at possible hand grazing / walking and extension of forage eating time.
Concentrate Portion Of The Diet:
Any inclusion of cereal or concentrate increased colic risk over forage only diets. The risk was greater as the amount of concentrate increased, even if the concentrate was split in to several feedings per day.
Racehorses in hard work need to consume concentrates to meet their energy requirements. Risk can be diminished by building the diet around forage and ensuring that at least 1% of BW is fed as long forage, preferably 1.5% of BW. Look for high energy concentrate feeds that provide part of the calories from fat (oil or rice bran) to help to reduce the dependence on cereals. Remember the rule of thumb that a single concentrate meal should not be greater than 5 pounds or 2.2 Kg.
Water deprivation increases colic risk. Stabled horses with automatic waterers had more colic cases than horses watered from buckets.
It is difficult to keep track of water consumption with automatic waterers, so an owner may not know of the horse has stopped drinking or decreased his water intake. Horses should always have access to plenty of fresh clean water. Monitor water intake.
History Of Previous Colic:
Horses that had been treated for colic were more likely to have another episode than horses that had never suffered from colic.
Management strategies that led to the first colic could, of not been modified and leave the horse at risk for further episodes. If colic surgery was done, adhesions or other complications could lead to another attack.
Research has shown that the major cause of gastric ulcers in racehorses is prolonged exposure of the squamous mucosa to gastric acid. The squamous cells in the upper region of the stomach do not have a mucous layer and do not secrete bicarbonate on to their luminal surface to protect them against the gastric acid. The only protection that this portion of the stomach has from gastric acid and pepsin comes from saliva production. If adequate saliva is not produced to buffer the gastric acid and coat the squamous epithelium, gastric irritation occurs and lesions may develop.
The high incidence of ulcers seen in racehorses is a manmade problem resulting from the way in which we feed and manage these horses, since ulcers are extremely rare in horses that are maintained solely on pasture. Horses evolved as wandering grazers with digestive tracts designed for the continual consumption of forage. Meals of cereals, or extended periods of time without forage lead to excess gastric acid output without adequate saliva production.
Horses secrete acid continually whether they are fed or not. The pH of the stomach contents in horses that had feed withheld for several hours has consistently been measured to be 2.0 or less (Murray, 1992). Horses that had access to plenty of forage had pH measurements that were significantly higher than those horses that had been fasted (3.1). Providing optimum intakes of forage stimulates saliva production, which is then available to help buffer and neutralize stomach acid.
The symptoms of ulcers can show in various ways and is likely to be different between individual horses. Signs that may suggest that a horse has gastric irritation include, irritability, poor coat, reduced performance, loss of body condition, and reduced appetite.
Treating ulcers requires the use of drugs that inhibit gastric acid production such as Gastro-Guard. An alternative to suppression of acid production is to neutralize stomach acid and protect the squamous mucosa from exposure to acid using gastric protectants such as KER Rite Trac.
Laminitis Associated With Carbohydrate Overload (Diet induced laminitis)
Sugars and starches are hydrolyzed in the equine small intestine up to the point at which the enzymatic capacity becomes overloaded and the excess starch is rapidly fermented in the hindgut. The critical capacity for starch overload appears to be in the range of 0.35-0.4% of body weight per feeding (Potter et al.1992), but maybe as low as 0.2% depending upon the type of starch source that has been ingested e.g. oat, barley or maize starch (Kienzle et al. 1992).
Overfeeding non-structural carbohydrates causes laminitis. Undigested starch reaches the hindgut where it is rapidly fermented by gut bacteria, which causes a disturbance and a shift in acidity, release of toxins and other substances and a leaky gut wall, allowing these substances to enter the circulation. The total understanding of the link between the hindgut disturbance and the disease process in the foot is still being researched, but it is firmly believed that it is this process that leads to the cascade of events mentioned, ultimately leading to laminitis.
Starch loving bacteria ferment the starch to produce propionic acid and a large amount of lactic acid. Although lactic acid can be used to produce glucose, large amounts of lactic acid and its accumulation may overpower the buffering mechanism of the hindgut and cause a drop in pH. Under normal healthy conditions, for example in horses on a high forage diet, the pH of the hindgut would be in the region of 6.5-7.0. The bacteria that ferment fibre and forage, Ruminococcusalbusand fibrobacter succinogenes, are sensitive to changes in the pH. During lactic acid accumulation the pH falls to below 6, which is referred to as sub-clinical acidosis and at this point the fibre digesting bacteria start to die.
Keeping meal single meal sizes to no more that 2.2 Kg per meal. If more concentrate feed is required, then look to increase the frequency of feeding. Time released hindgut buffers, such as KER Equishure, can help to maintain a normal pH during times where there is a greater reliance on high starch and cereal diets without adequate levels of forage.
By Lizzie Drury, MSc Registered Nutritionist, Saracen Horse Feed proudly distributed by www.eurovetsworld.com