There are a number of reasons owners look at the starch content of their horses feed. Health concerns, energy levels and comparing feeds are the common reasons. It is difficult to know which levels are ideal and suited to those that may tip your horses head over the edge. Again, this will also have some variables such as temperament, health concerns, workload, season and age of the horse or pony.
Carbohydrates and sugars are crucial in equine health for providing energy. There are non-structural carbohydrates such as glucose, fructose and starch. The non-structural carbohydrates are readily digested and absorbed in the small intestine and cause a rise in blood glucose which results in an increase in blood insulin levels. Some ingredients which are higher in non-structural carbohydrates are oats, barley and corn. The Structural carbohydrates are most commonly found in forages and high fibre ingredients such as Soya Hulls, beet pulp and alfalfa. The structural carbohydrates are another source of energy however, they do not result in a an increase in blood glucose or insulin levels.
After the horse has consumed starch, it is broken down by enzymes and converted to glucose to be more readily absorbed. The benefits of being readily absorbed is particularly important for the harder working horse for energy supply and generation. The horse will experience a higher blood glucose up to 2 hours after consuming a feed, which can effect some horses. Glucose can be passed through the blood – brain barrier which increases the production of dopamine. Dopamine can induce awareness and excitability which is beneficial to horses in harder work such as racing and eventing however can cause over excitability in horses not exerting the energy.
High starch diets can cause problems if your horse does not require a high calorie diet. There are limited enzymes in the small intestine that breakdown starch. This can be a problem if the starch reaches the large intestine. This process is called starch overload. Starch will be rapidly fermented in the large intestine however, this process can cause digestive upset as the by-product of starch digestion is lactic acid. Lactic acid increases the acidity in the hindgut which then kills off the good fibre digesting bacteria causing hindgut acidosis. Hindgut acidosis can lead to negative behaviour, poor performance and mild colic and Laminitis.
If your horse requires quick release energy and requires a higher starch diet it is recommended you allow your horse access to forage before the hard feed as this will naturally slow the rate of which food will pass through which will reduce the risk of undigested starch reaching the hindgut. Feeding smaller meals will also make it easier for the horse to break down the starch. It may also be beneficial if feeding a higher starch diet to consider feeding a probiotic to support the hindgut bacteria such as Yeasacc 1026 or Brewer’s Yeast. Most of Rowen Barbary’s feed range contain some digestive support to help maintain hindgut bacteria health.
Levels of Starch
Levels of starch very in each feed depending on the ingredients included. Research varies on determining the different levels of what levels are classed as high and what are classed as low. On average, studies suggest any feeds below 10-12% of starch are low in starch and anything from 20% and above is classed as high. Leaving the mid-range of starch between 13 – 19%. These levels may vary between each feed company and it is important to check the nutritional analysis found on the back of feed bags to determine what level of starch is present within the feed. It is recommended that the diet contains less than 2 grams of starch per kilogram of bodyweight per day. Or 1g per kilogram of bodyweight per meal. This would mean a 500kg horse can consume up to 1000 grams a day or 500 grams per meal (if fed twice a day). This will depend on your horses health, age, workload/fitness level and body condition.
Some horses require low starch diets due to their temperament or horses with metabolic health concerns, muscle disorders or reactive horses. Any horses with starch sensitivity requiring a low starch diet should be gradually changed over to avoid digestive upset. In some cases, horses diets to suddenly change such as when a horse is diagnosed with Laminitis. If a change is immediate and cannot be gradually altered, it is important to observe your horse for any loose droppings which will be a result of digestive upset.
Feeds can be manufactured with low levels of starch for horses requiring low energy levels such as Rowen Barbary’s Forage ‘n’ Fibre, horses requiring more condition and those that are in moderate to hard workloads. Calorie dense feeds that are low in starch usually contain higher level of oil such as Rowen Barbary’s Solution Mash.
A low starch diet is not necessary for all horses and very much depends on their health. Before making any dietary changes you may want contact the feed company to see what they determine as low starch and speak to a nutritionist if unsure or requiring any further advice.
Rowen Barbary’s nutritionists are available at email@example.com
Eleanor Blinkhorn (Bsc) | Equine Nutritionist