FEEDING FOR IMPROVED BEHAVIOUR
Heating Sugars and Starch
Starch is one of the best sources of energy for working horses. However, excess starch and sugars can lead to a build up of glycogen in the muscle cells, which is then broken down anaerobically, causing damage to the tissue and resulting problems. These feeds need to be moderated in performance horse diets to help keep them calm and 'cool'. Sources
Digestion
Grain and grasses (including grain and meadow hays) are the main sources of starch and sugars. Sugars include glucose, fructose, sucrose and fructans. Starch consists of chains of glucose and fructose molecules, and is found in hay, warm season grasses and grains. Cool season grasses are higher in fructans. Many pellets are high in carbs.
Sugars and starch are non-fermentable carbohydrates (as opposed to fibre, which is fermentable). Fermentation is a digestive process of bacteria in the large intestine. The small intestine digests feed using enzymes.
Average Starch+Sugar contents: Soy bean hulls: Lucerne hay: Grass pasture: Beet pulp: Grass hay: Rice bran: Wheat bran: Oats: Barley Corn:
6.3% 11.3% 12.1% 12.3% 13.8% 21.0% 30.8% 54.1% 61.7% 73.3%
Grains and grass are the major NSC sources
Starch and sucrose can be digested well in the small intestine, where enzymes break them down into simpler sugars. But excess starch, and fructans, cannot be processed in the stomach, and overflow into the hind gut. Here the bacteria cannot break them down either, but instead ferment them into lactic acid, which lowers the pH and can eventually destroy most of the 'good' bacteria.
Physiological Effects Horses fed on grain use more glycogen for energy output than Volatile Fatty Acids (VFAs). VFAs provide a slow-release source of energy from adipose tissue. Some glycogen is stored in the liver, and available from there as an an aerobic energy source, but most glycolysis is intramuscular - that is, sugar from feed stored in the muscle cells is broken down inside them to produce energy. This process results is the production of lactic acid, which damages the cells.
Stance Cool Stance: 11.1% Mitavite Economix: 31.5% Mitavite Gumnuts: 33.0% Barastoc Calm Performer: 30.7% Pryde's EasiResult: 42.6% Weightlifter Calm: 40.0% Barastoc Cool Command: 43.4% Easi-Rider Cool Mix: 46.0%
Indications Horses in intensive work do require starch and sugar for their anaerobic energy metabolism, to fuel the glycolysis process.
Sources for NSC percentages: www.equilize.com.au; www.triplecrownfeed.com; www.safergrass.org
Contraindications
Results
Horses that founder, colic or tie-up will require a very low non-structural carbohydrate diet. Those with PSSM or other sugar storage myopathies also need to avoid starches. Horses that are 'fizzy' in general will benefit from a diet that produces less acid, which can disrupt the central nervous system and cause agitation and anxiety. Because sugars and starch have a high glycemic index, they can cause energy spikes. Fats and fibre provide a less variable fuel source to sustain energy without the acid waste fizz and heat.
Hot horses transitioned from a high sugar and starch diet to one incorporating more fats and fibre will fatigue less easily from muscle cell damage during exercise, be less reactive to ride and handle, and be at recuded risk of metabolic issues such as tying-up, colic (hind gut acidosis) and founder.
Safe Feeding To avoid overload of carbs and sugars from grain and grass hays, they can be soaked overnight and then drained. Substituting lucerne or other legume hay will eliminate fructans and many problematic carbs. Grains can be substituted for 'super-fibre' sources like beet pulp, which provides similar energy without the NSCs. Grains should be fed rolled, or preferably extruded or micronised, to aid digestibility. Hays made form grain crops are especially high in starch content, as they are cut when in flower, when their sugar content is at it highest. The NSCs in lucerne are largely pectin, a relatively 'safe' carb.
For more see http://lucanlodge.net