b'NUTRITION KRISTEN JANICKI, MSTheHorse.com/NutritionA Quick Guide to MacronutrientsUnderstanding the roles of carbohydrates, fats,and proteins in the equine dietprovided by pasture and hay constitute Structural carbohydrates inthe greatest percentage of the total diet grass and hay meet 50-100%and meet 50-100% of the horses total of a horses total energy needsenergy needs. Grains with fibrous hulls, at maintenance. such as whole oats, and byproduct feeds, such as beet pulp, also contribute to the diets structural carbohydrates. How do horses utilize structural carbs? Equids are not capable of digesting fiber without the help of billions and billions of bacteria residing in the hindgut (the intestinal tract behind the small intes-tine). Microbial fermentation breaks fiber down into usable forms of energy known as volatile fatty acids. The three main volatile fatty acids (VFAs) microbial fermentation produces are propionate, acetate, and butyrate, which travel through the large intestines walls and into the bloodstream. The body can use acetate, produced in the highest concentration of the three, for energy or convert it into long chain fatty acids to store for later use. Propionate can end up in the liver for conversion to glucose (sug-ISTOCK.COMars) in a process known as gluconeogene-sis. Butyrate is the preferred energy source of the cells lining the intestinal tract.I f youve ever used a fitness or meal- a certain amount of energy per day forFiber could almost be its own macro-tracking app on your phone, youremaintaining body condition and essentialnutrient. Besides contributing to daily probably familiar with the term mac- biological functions (otherwise known asenergy requirements, fiber supports a ros. Short for macronutrients, theyremaintenance requirements). Pregnancy,healthy microbial population in the hind-the three main suppliers of nutrients inlactation, growth, training, and perfor- gut and helps prevent colic, gastric ulcers, human and horse diets: carbohydrates,mance increase energy requirementshindgut acidosis, and unwanted behav-fats, and protein. Theyre necessary forabove maintenance.iors such as cribbing or stall-walking. all facets of life, from energy provisionCarbs in the diet can be classified intoHowever, researchers have yet to quantify to cell membrane structure support. Intwo groups by plant structure or by howa fiber requirement for horses. this article well describe the function oftheyre digested: Nonstructural carbohydrates include macronutrients in a horses diet and the1. Structural carbs include the fibrousall the mono-, di-, and oligosaccharides sources from which theyre derived. portion of plants (aka fiber).and the polysaccharide starch. Digestive 2. Nonstructural carbs (NSCs) includeenzymes typically break NSCs down in Carbohydrates the polysaccharides cellulose andthe foregut (everything ahead of the large Carbs are the main calorie sourcehemicellulose.intestine) to simple sugars, or monosac-for helping meet a horse or ponys dailyBecause horses are continuous graz- charides, that get absorbed through the energy requirements. Every equid needsers, it makes sense that structural carbssmall intestine. The body can immediately 32August 2019The Horse | TheHorse.com'