Author: Ken Wilkinson, Nutritionist, Member of Equine Science and speaker at HCBC’s Community Talks Travelling Road Show
Grasses store their energy as the compound fructan. Administering very high levels has been used as a model for creating laminitis in horses in recent research. Traditionally we thought the high load of rapidly fermentable carbohydrates in the hind gut were the basis for a cascade of events; from that caused laminitis.
A new approach is to consider how fructans change the gut microflora.
In the hind gut it is known as Streptococci species (bacteria) which increases with fructans.
Laminitis also occurs with symptoms of equine metabolic syndrome such as insulin resistance, often with
Hypertriglyceridemia, hypertension and obesity (with fat deposition in the neck and tail head, for instance Cresty Neck Syndrome).
It is possible that chronic ingestion of fructans may induce the expression of Streptococci whose enzymes along with a massive supply of fructose can lead to a production of fructose very rapidly. Some of the fructose would be metabolized in the intestinal wall and the pathway used by the fructose is a little different than that of glucose which creates a local inflammation with increased intestinal permeability and endotoxins. Some fructose may enter the liver to stimulate insulin resistance and the remaining may be degraded by local bacteria resulting in local acidosis.
Evolution has resulted within the fructans in grass, providing the source of nutrients for grasses in difficult times such as drought.
The fructans may also act as an anti-freeze (cryopectant) for grasses. Animals also evolved along with these grasses, consuming and becoming obese during times of plenty which can be an advantage of a cold harsh winter is coming. That is actually why many pony breeds are easy keepers and prone to insulin resistance and laminitis. Ponies are genetically selected to be insulin resistant. They are adapted to a harsh climate where gaining weight easily was an advantage. However we do not allow the rhythm of nature to occur. Weight gain in the summer is not lost in winter and in fact carries on to obesity overtime.
We generally manage horses and ponies to consume high fructan grasses or hays free choice. The grass may actually be selected to be even higher in fructans than one would counter with a wild grass. The problem is further compounded by the rain fall and autumn stimulating grass growth again increasing yields. The fructans are then trapped in the grass when the evening temperature drops below about 5°C or 40°F. So we have a perfect storm for high energy intake and high fructan intakes. It’s no wonder horses and especially ponies founder in our climate zone with our types of equine management systems.
This research stems from ongoing work with fructans where lab animals and humans are becoming obese and suffering from metabolic syndrome of fructose based diets but not on the same calorie level from glucose. Fructose has a different biochemical pathway and great harmful end products during the process. Please note experts feel horses have as much bacteria in the small intestines as the hindgut so they are unique and how they handle carbohydrates. We know horses can eat 10 to 15 kg of pasture grasses and the grasses can provide up to 7 kg fructans a day. So be careful in the spring and watch out for high sugar hays.
For assistance in designing the best diet for your horse contact your Veterinarians, Farriers and Nutritionists and remember to analyze your hay in order to balance a diet that fits the needs of your horse. Always feed by weight not by volume.
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