Texas Equine Veterinary Association

• 14 • is consumed by the horse. We want to minimize these as much as possible in the hard keeper by offering a highly digestible ration that the horse can easily utilize. Performing a hay analysis at your local forage lab and choosing a forage with a lower non-detergent fiber (NDF; 45–52%) will allow the horse to better utilize the forage. Fresh green spring grass is much more digestible than hay and can be a good alternative to preserved forage when available. Calorie Density Maters Not all forages provide the same caloric density, regardless of quality. Cool season forages, such as ryegrass and fescue, have a higher energy density per unit weight than warm season forages. Alfalfa has the highest energy and protein values of all the forage options for horses. Selecting a cool-season forage can increase the caloric content of the diet by approximately 5 Mcals per day over a warm-season forage. For example, our 500 kg horse receiving legume hay at 2% of body weight per day would equate to approximately 26.2 Mcals per day total vs. bermudagrass hay at approximately 20.8 Mcals per day total. If 20 Mcals over the daily calorie requirement level is necessary to gain 1 kg of body weight (NRC 2007), the difference in forage type in our example would mean the legume hay could provide 1 kg of body weight gain every 2 ½ days vs. over 7 days for the bermudagrass diet. When fiber in the form of hay or pasture is unavailable, beet pulp is a quality source of fiber that can be used to add energy to a diet. It can be fed in large amounts without harming the horse, is highly digestible, and can be fed on its own without vitamin/mineral fortification because of its favorable nutrient composition. Other more readily available sources of processed fiber are alfalfa cubes or pellets, which can be found at a local feed store year-round. It is recommended that alfalfa cubes and pellets are soaked before feeding to prevent choke. Dry matter, % Crude Protein, % Digestible Energy (DE), Mcal/kg Legume 91 21 2.62 Beet pulp 92 9 2.64 Bermudagrass 93 11 2.08 Values represent accumulated samples from data collected between 2004- 2018. ©Equi-Analytical 2020 Dry matter % - everything in the sample minus water, including protein, fiber, fat, minerals, etc. Crude protein % - the total protein in a sample, including protein and non- protein nitrogen sources. Pagan (1998) has developed an equation to estimate the digestible energy (kcal/kg DM) from feed: 2,118 + 12.18 × (%crude protein) – 9.37 × (%acid detergent fiber) – 3.83 × (%hemicellulose) + 47.18 × (%fat) + 20.35 × (%non-structural carbohydrate) -26.3 (%ash); R2 = 0.88, where hemicelluose = acid detergent fiber – neutral detergent fiber and non- structural carbohydrate = 100 - %neutral detergent fiber - %fat - %ash - %crude protein. Benefits of Good-Quality Pasture A well-maintained pasture can supply most nutrient requirements for horses when stocked appropriately during seasons of growth. is graph is showing the digestible energy requirement of the different feeding classes of horse. An average pasture may contain between 2– 2.5 Mcals/kg of digestible energy on average, as shown in the green highlighted area on the graph. e digestible energy content from pasture can meet the needs of most feeding classes. If consumed at a feeding rate of 2.5% of body weight per day, pasture could provide 160% of maintenance calorie requirements (NRC, 2007). erefore, hard keepers kept on lush pasture could maintain or even increase body condition. is provides the owner with a low-cost alternative to supplemental feeds, while minimizing the risk of colic and equine gastric ulcer disease. Supplementing the Diet Unfortunately, most horse facilities do not have the luxury of copious pasture grass because of space restrictions. Also, hard keepers cannot maintain adequate body condition on dried forage alone. It is generally too bulky to consume at rates higher than 2% of body weight per day in dry matter. Commercial grains are high in digestible starches that can be easily broken down for energy. Grains should be pelleted or extruded to increase digestibility and useability by the horse pre-cecally. Grain may comprise between 20–40% if the diet but should never exceed 50% of the diet because of the heightened risk for colic. e danger of feeding too much starch is the effect of unprocessed grain fermenting in the hindgut. is produces lactic acid which causes the hindgut to become more acidic, which kills good bacteria in this region of the digestive tract. e bacteria, unaccustomed to a low pH, die and produce endotoxins that may lead to colic and laminitis. Horses with sensitivity to simple sugars and starch should only receive low starch rations, probiotics, and enzymes to help maintain healthy microbial populations in the gut. Dietary fats are an excellent tool for putting weight on hard keepers. Fats contain 2.25 times more calories per unit weight than carbohydrates without the risks that starches pose for the horse. Oils contain 100% fat and oilseeds contain around 25% fat. Common sources of fat include rice bran, linseed, sunflower seeds, full-fat soybeans, and coconut meal. Rice bran is an excellent source of fat for building a horse's topline and adding shine, but it can go rancid very quickly so it must be stabilized through extrusion. Fats are beneficial to the horse because of their high palatability, no negative effect on cecal pH, cool metabolizable energy, and skin and coat health. Fat supplements are manufactured commercially for horses or can be found at the local grocery store (in oil form). One cup of vegetable cooking oil can be used to top dress a ration, adding up to an additional 3 Mcals per day of energy to the diet. Be aware that not all fats

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