Beyond the NRC: Designing the Ideal Ration Meri Stratton Phelps, DVM, MPVM, DACVIM (LAIM), DACVN When it comes to proper nutrition, veterinarians, horse owners and nutritionists all have the same goal in mind: to develop a ration that will ensure good health, optimal performance, and a long life for the horse. The ideal ration of each horse starts with a foundation of forage. The next ingredients vary depending on the horse s life stage, the regional availability of different feeds, and the preferences of owners and veterinarians. Forage rations without any supplementation rarely meet all nutrient requirements (Trial Figure 1). In many cases a ration with high quality pasture grass and/or hay and a vitamin, mineral, essential fatty acid, and antioxidant rich supplement may be all that is required to ensure that the ration is optimized. In other cases, supplemental energy, protein, essential fatty acids, vitamins and minerals may be needed to ensure adequate intake of nutrients for more demanding life stages including light to very heavy exercise, pregnancy, lactation and growth. : Beyond the NRC A complete and balanced ration contains all essential nutrients including protein, essential fatty acids, vitamins and minerals. Beyond meeting the NRC requirements for different levels of work or life stage, the combination of certain nutrients including omega-3 and omega-6 fatty acids and dietary antioxidants play an important role in modifying the inflammatory response, and in protecting the horse from cellular oxidative damage, respectively. Essential Fatty Acids Both omega-3 and omega-6 fatty acids are required in the horse s ration because they are unable to synthesize these fats. Forage often contains a high enough concentration of omega-6 fats like linoleic acid, and supplementation is rarely required. Omega-6 fats are found in high concentrations in most grains, and in many vegetable oils. Horses that are fed commercial feeds or grain supplements consume much higher concentrations of omega-6 fats than are required. The essential fatty acid profile of grain or commercial feed-supplemented rations do not resemble the ideal omega-3 to omega-6 ratio that is consumed when horses eat a natural diet of forage (Figure 1). Figure 1. Ratio of Omega-3 to Omega-6 Fatty Acids Natural Grazing Diet Omega-3 Omega-6 Omega-3 Typical Modern Diet Omega-6 Dietary lipids of either the omega-6 or omega-3 class are eventually incorporated into cell membranes. Once inflammation occurs in tissues, mediators including prostaglandins and leukotrienes are produced. Omega-3 fats result in less potent inflammatory mediators, and when the concentration of dietary omega-3 fats is increased, the systemic response to inflammation can be blunted (Figure 2). Figure 2. Diet High in Omega-3 Fatty Acids Anti-Inflammatory Omega-3 Fatty Acids Anti-clotting COX Enzymes Omega-6 Fatty Acids Pro-inflammatory Pain, fever inducer
Even when horses consume a hay-based ration, their omega-3 intake will be significantly less than a horse that consumes fresh pasture due to the decline in the concentration of omega-3 fatty acids that occurs after hay has been harvested (Figure 3). Figure 3. Concentration of Omega-3 Fatty Acids in Alfalfa Hay Before and After Harvest Omega-3 Fatty Acid (%).7.6..4.3.2.1 Whether an equine ration is one that only includes hay, or is one that contains forage in combination with grain or commercial feed or an oil that is rich in omega-6 fatty acids, supplementation with plantbased omega-3 fatty acids will help to rebalance the ratio of omega-3 to omega-6 fatty acids toward that of a natural grazing diet (Figure 1). Dietary Antioxidants, vitamin C and selenium work to protect cells against damage from oxygen free radicals. In the horse, free radical production has been documented in a variety of disease states including laminitis, joint disease, as well as during exercise. 1- Even healthy horses are susceptible to oxidative stress caused by free radical damage if they consume commercial feed or oil that has become rancid due to fat oxidation. Oxidative damage to fat can occur when heat is used as the feed is manufactured, and can occur over time if the feed is not stored properly. Consumption of peroxides in commercially produced horse feed leads to measurable cellular oxidative damage with increased concentrations of blood protein carbonyls and thiobarbiturate reactive substances (TBARS) (Figures 4 and ). Fresh 6 Weeks Post Harvest 1 Weeks Post Harvest Figure 4. Damaged Protein Content Following Six Weeks of Supplementation with an Omega-3 and Micro-nutrient Product* vs. Supplementation with a Commercial Feed Protein Carbonyl (nmol/mg protein) Figure. Damaged Fat Content Following Six Weeks of Supplementation with an Omega-3 and Micro-nutrient Product* vs. Supplementation with a Commercial Feed TBARS (micrmol/l) 3. 2. 2. 1. 1...4.4.3.3..2..1. Supplemented* Rancid feed should be easy to identify due to changes in odor, and refusal of the feed by a horse. However, an analysis of newly purchased fresh bags of readily consumed commercial equine feeds reveal rancidity with concentrations of lipid peroxides that are well above the recommended level of consumption of 1-1 meq/kg fat (Figure 6). Commercial Feed Significantly (p<.) lower than Commercial Feed value Supplemented* Commercial Feed Significantly (p<.) lower than Commercial Feed value Figure 6. Peroxide Comparison Between an Omega-3 and Micro-nutrient Supplement* and Commercial Feeds Peroxides (meq/kg fat) 3 3 2 1 Supplement* A B C D E *Platinum Performance Equine Wellness and Performance Formula
Although most equine commercial feeds are supplemented with selenium and vitamin E and maybe even vitamin C, oxidative damage to the fat in commercial equine rations counteracts the protective effect of these antioxidants in preventing cellular oxidative damage once the feed is consumed by the horse. Even high quality forage may contain high concentrations of peroxides, subjecting the horse to a high load of free radicals that will cause cellular damage when the horse is consuming a more natural ration. Because the concentration of vitamin E in hay rapidly decreases after harvest (Figure 7), supplemental vitamin E above the concentration recommended in the 27 Horse NRC becomes an essential component of the optimal equine ration. 6 An easy and effective way to combat the oxidative damage that will occur from consumption of peroxides in the equine diet is to add a low peroxide, antioxidant rich omega-3 and micronutrient supplement* to the ration. A small volume (132 grams/day) of this supplement significantly reduces the concentration of both protein carbonyls and TBARS in the blood in as little as 3 weeks (Figures 8 and 9). Figure 7. Concentration of in Alfalfa Hay Before and After Harvest (IU/lb) 4 3 3 2 1 Figure 8. Damaged Fat Content Before and After 3 Weeks of Omega-3 and Micro-nutrient Supplementation* 1.6 Fresh 6 Weeks Post Harvest Fasting Figure 9. Damaged Protein Content Before and After 3 Weeks of Omega-3 and Micro-nutrient Supplementation* Protein Carbonyl Content (nmol/mg protein) 1. 1.4 1.3 1.2 1.1 1..9.8.7.6 Putting it into Practice Fasting An adult Thoroughbred gelding was fed a forage ration of ad libitum alfalfa and oat hay until his weight was stable. An antioxidant, omega-3 and micro-nutrient supplement* was then added to the ration with 66 grams fed twice daily for a total daily dose of 132 grams. No other changes were made in the husbandry of the horse. During the supplementation period, the daily volume of alfalfa and oat hay offered remained constant (17.44 pounds alfalfa hay, 18 pounds oat hay). Oat hay was always provided in excess of what the horse would consume. All of the alfalfa hay and the entire volume of the supplement were consumed daily. Ration analysis (Trial Figures 1-9) and horse photos are shown below. Despite consumption of 2.7% body weight as alfalfa and oat forage, nutrient requirements for a 6 kg adult horse at a physiologic state of maintenance were not met before the supplement was added (Trial Figure 1). Addition of the antioxidant, omega-3 and micro-nutrient supplement* resulted in an optimized ration without nutrient excesses. The daily dose of the antioxidant, omega-3 and micronutrient supplement* used in this trial (132 grams) is less than the recommended daily dose of 198 grams for a horse that weighs over 6kg. 2 Hours Post-Feeding Significantly (p<.) lower than value TBARS (millimolar) 1.4 1.2 1..8 2 Hours Post-Feeding.6 Significantly (p<.) lower than value *Platinum Performance Equine Wellness and Performance Formula
Picture A. Before supplementation with an antioxidant, omega-3 and micro-nutrient supplement* Horse 1, 63 kg Picture B. After 8 Weeks of supplementation with an antioxidant, omega-3 and micro-nutrient supplement* Horse 1, 621 kg Trial Figure 1. Ingredient Contribution of Essential for a 6 kg Adult Horse, Average Maintenance Trial Figure 4. Ingredient Contribution of Essential for a 6 kg Adult Horse, Average Maintenance 6 6 % Rec from Supplement* 4 3 2 1 4 3 2 1 Trial Figure 2. Essential Fatty Acid Concentration Trial Figure. Essential Fatty Acid Concentration 3 2 1 Alfalfa Hay (18 lb) Oat Hay (9.96 lb) Supplement* ( g) Trial Figure 3. Antioxidant oncentration 2 18 16 14 12 1 8 6 4 2 Alfalfa Hay (17.44 lb) Oat Hay (9.98 lb) Supplement* (132 g) Trial Figure 6. Antioxidant oncentration 8 8 7 6 4 7 6 4 3 3 2 2 1 1 Alfalfa Hay (18 lb) Oat Hay (9.96 lb) Supplement* ( g) Alfalfa Hay (17.44 lb) Oat Hay (9.98 lb) Supplement* (132 g) * Platinum Performance Equine Wellness and Performance Formula Nutrient Requirements of Horses (ed 6), 27
Picture C. After 11 Weeks of supplementation with an antioxidant, omega-3 and micro-nutrient supplement* Horse 1, 623 kg Trial Figure 7. Ingredient Contribution of Essential for a 6 kg Adult Horse, Average Maintenance Literature Cited 1. Neville RF, Hollands T, Collins SN, et al., Evaluation of urinary TBARS in normal and chronic laminitis ponies. Eq Vet J, 24;23(3):292-4. 2. Dimock AN, Siciliano PD, Mcllwraith CW, Evidence supporting an increased presence of reactive oxygen species in the diseased equine joint. Eq Vet J, 2;32():439-43. 3. Kinnunen S, Hyyppa S, Lappalainen J, et al., Exercise-induced oxidative stress and muscle stress protein responses in trotters. Eur J Appl Physiol, ;93(4):496-1. 4. Kinnunen S, Hyyppa S, Lehmuskero A, et al., Oxygen radical absorbance capacity (ORAC) and exercise-induced oxidative stress in trotters. Eur J Appl Physiol, ;9(-6):-6.. Mills PC, Smith NC, Casas I, et al., Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse. Eur J Appl Physiol Occup Physiol, 1996;74(1-2):6-6. 6. Nutrient Requirements of Horses, (ed 6) Washington, D.C., The National Academies Press, 27, pp. 19-127. 9 % Rec from Supplement* 8 7 6 4 3 2 1 Trial Figure 8. Essential Fatty Acid Concentration 2 18 16 14 12 1 8 6 4 2 Alfalfa Hay (17.44 lb) Oat Hay (9.98 lb) Supplement* (132 g) Trial Figure 9. Antioxidant oncentration 8 7 6 4 3 2 1 Alfalfa Hay (17.44 lb) Oat Hay (1.13 lb) Supplement* (132 g) * Platinum Performance Equine Wellness and Performance Formula Nutrient Requirements of Horses (ed 6), 27