b'use simple sugars that enter the blood- COMMON CARBOHYDRATE SOURCES IN EQUINE RATIONSstream for energy, store them as glycogen in the muscle and liver, or use them forStructural Carbohydrates Nonstructural Carbohydratesfat synthesis. Nonstructural carbs not di-Fresh pastureBeet pulpOatsWheat brangested in the small intestine (due to large Baled legume or grass haySoy hullsCornWheat middlingsconcentrate meal size, for example) get Forage cubes or pelletsOat hullsBarleyCorn glutenfermented in the hindgut. Certain NSCs WheatRice bran(e.g., fructans found in fresh pasture) PeasMolasseshave been known to resist enzymatic hydrolysis (breakdown) in the small intestine, passing through to ferment in the hindgut instead. When the hindgutCOMMON FAT SOURCESbacteria ferment these NSCs, they pro- Grain-Based Fat Sources Oil-Based Fat Sourcesduce lactate rather than VFAs, potentially disrupting the hindgut environment and Flaxseed or LinseedCopra mealCorn oilCoconut oilincreasing colic or laminitis risks.Stabilized rice branCanola mealCanola oilPeanut oilCereal grains are by far the largest NSC Whole soybeansWheat germSoybean oilPalm oilsources, although pasture and hay do con-Sunflower seedsRice bran oilFish oiltain various percentages of sugars. Com-Sunflower oilmon cereal grains include oats, barley, and corn. Byproduct feeds, such as wheat middlings, corn gluten, and rice bran, alsoCOMMON PROTEIN SOURCEScontribute to the diets starch content.Grain Protein Sources Forage Protein SourcesFatsFats serve a variety of functions in Whole soybeansDistillers dried grainsFresh pasturehorses, including transporting fat-soluble Soybean meal Corn gluten mealLegume hay (e.g., vitamins; delivering essential fatty acids, Brewers dried grainsLinseed meal alfalfa, clover)which are not made by the body; provid-ing cells with structural integrity; and serving as precursors to hormones andcarbon molecules internally. Single bondsdifferences in fat source digestibility in other signaling molecules. Fats and oilslink carbon atoms in saturated fats. horses. Fats from forages appear to be fall into a class of molecules called lipids.Conversely, one or more double bonds55% digestible, compared to 100% for Structurally, all fats contain: link carbon atoms in unsaturated fats.oils. Common fat sources include grain- A single glycerol moleculea chainOnce ingested, enzymes called lipases inbased and oil-based fats.of three carbon atoms, each with athe horses stomach begin to break downMany horses on pasture or hay will hydroxyl group (oxygen and hydrogen)the fat bonds, with most digestion takingobtain sufficient fatty acids from the for-bound to it; and place in the small intestine. After absorp- age, says Valentine. However, there areFatty acidslong hydrocarbon (con- tion, fatty acids get transported to themany horses that appear to be metaboli-taining hydrogen and carbon) chains. muscle, liver, adipose (fat) tissue, or else- cally different and whose muscle cells Of course, fats most recognized func- where as needed for storage or use. Fatsseem to need additional fat to allow for tion is providing energy for cells, particu- that dont get broken down and absorbednormal muscle health, function, and larly heart and muscle cells, with glucosein the small intestine travel to the hindgut,performance. and glycogen being the other majorwhere they get excreted in the feces. In these scenarios you might need to sources of cellular energy.The horse evolved to ferment the fibersupply additional fat in your horses diet.In most species of animals, musclein forage to fatty acids, courtesy of large cells are either designed to rely mostly oncolon (the second part of the hindgut)Proteinglucose/glycogen for energy oron fatbacteria, says Valentine. These fattyMost equine body tissues contain for energy, says Beth Valentine, DVM,acids get absorbed into the bloodstream,protein, with muscle containing the most. PhD, Dipl. ACVP, professor of anatomicand some are converted to sugars usedProteins help make up body tissues, pathology at Oregon State University, into fuel cells like those in the brain, whichincluding everything from muscle to hair; Corvallis. But in the horse, studies foundrely almost entirely on sugars for energy.function as enzymes and hormones in the that even muscle cells designed to useThe horses body uses other fatty acids formetabolic machinery of the horse; and glucose/glycogen for energy also haveimmediate energy and to ensure adequateplay an important role in the immune fatty acid transporters on their surface.fat stores for future energy needs whensystem as antibodies, says Sara Mastel-This is understandable when youfood is scarce.lar, PhD, assistant professor at Ohio State consider that horses do not have specificGrains, seeds, and nuts (such as pea- University ATI, in Wooster. fat requirements but, rather, fatty acidnuts) that horses might encounter whileProteins consist of various-sized chains requirements.browsing can supply additional fats, sheof about 22 different amino acids linked Dietary fats and fatty acids vary insays.together by peptide bonds. Horses can length and in the types of bonds linkingResearchers have identified drasticsynthesize most of the amino acids they TheHorse.com | The HorseAugust 201933'