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324 Energy Nutrients

324 Energy Nutrients - ENERGY NUTRIENTS The main focus of...

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Unformatted text preview: ENERGY NUTRIENTS The main focus of any horse‘s dieT is To ensure ThaT iT has enough ENERGY. Energy is NOT a nuTrienT. IT is The end producT of The digesTive breakdown of compounds conTaining carbon hydrogen and oxygen in an available form. The main Three nuTrienTs ThaT produce energy are carbohydraTes, faTs, and proTein. NUTRIENT SOURCES OF ENERGY: CARBOHYDRATES: Serve as The primary source of energy for The horse (TradiTional raTions). Roughly 75% of all planT maTerial is made up of carbohydraTes. NoT all CHO are equal. STrucTure, ‘70 of soluble/insoluble, proTein aTTachmenT,lignin, eTc. Influences digesTabilify. Choose specific CHO based on individual need. 50/Ub/e Carbohydrafes: Made up of SUGARS. Simple sugars - single or double sugar molecules. STarches — combinaTion of many sugars = polysaccharide. *GLVCOGEN — combinaTion of many polysacarrides. STrucTure of soluble CHO influences digesTion <3: availabiliTy. Simple sugars ~ 100% STarches vary by Type (source): OaTs > sorghum > corn > barley Grains are very HIGH in soluble CHO: Hay is very LOW: Green forage is InbeTween. I nso/ub/e Carbohydrafes: Made up of a very complex combinaTion of sugars and various combinaTions of C, H, O chains. Tough, rigid sTrucTures ThaT require specific sTrong enzymes for digesTion. Enzymes not produced by mammals. Can only come from specific bacTeria presenT in The horse's cecum and large inTesTine. Also known as planT fiber, insoluble CHO include: Cellulose and hemicellulose, which are fairly digesTible, and Lignin which is totally indigestible. About 50% of the insoluble CHO are digested, rest pass as manure. FATS: Fats are a Tremendous source of energy. Gm fat 2 2.5 gm CHO, or gm Protein. Grains : 3.0—3.5‘70 fat. Added fats can significantly increase energy level with no increase in potential colic problems. Increased caloric density of feeds. *PROBLEM: Increased caloric density reduces the amount of feed fed. Can alter energy/protein ratio. Can create eating behavior problems. PROTEIN: Protein is a nutrient class in its own right, but it CAN be used as a source of energy. Any protein fed beyond the horse's needs is used, or stored as energy. Protein, as a whole, is not a good source of energy. Increased production of ammonia. Expensive. ENERGY PARTITIONING: The chemical energy in feeds may be partitioned into the portion that is available for use by the horse and the portion that is lost. Energy requirements are expressed in calories. Calorie : the amount of heat (energy) required to raise 1 gm of water by 1° C. Kcal (kilocalorie) = 1000 calories Mcal (megacalorie) = 1000 kcal = 1 million calories GE TUE WME TNE *9 NEM FE UE ero HE \NE P GE : Gross Energy : Intake energy = total potential energy. GE : the amount of heat produced from the total combustion of the feed. Influenced by feed composition: FAT > CHO or Prot MGE starch : GE cellulose DE = Digestible Energy : GE — FE : energy available in the GIT for absorption FE = Fecal energy: energy lost in the feces Two factors influence DE of a feed: 1. GE content 2. Digestibility In general concentrate > forage DE ranges from 60%-90%+ for various feeds. ME = Metabolizable Energy = DE - UE - GPD : energy available for metabolism UE : Urinary energy: energy lost in the urine GPD : Gaseous products of digestion (CH4, C02, NH3); energy lost during digestion Composition of feed influences ME. Concentrates ~ 85%+ DE Hay ~ 65—85% (high digestibility increases ME) NE : Net Energy 2 ME - HE = energy available for physiological processes HE = heat production: conversion of Substrates to ATP results in a loss of heat Glucose : 85% ME FFA : 80% ME AA : 70% ME VFA : 65% ME NEM = Net Energy of Maintenance = energy required to sustain life Respiration, cardio—function, digestion, warmth NE: 2 Net Energy of Production = energy available for production purposes Weight gain, reproduction, exercise, growth Maintenance functions take 1ST priority for available energy. Energy for Production is only available if maintenance functions have been met, and additional energy is available. METABOLIC ENERGY SOURCES: ATP is the major source of energy available for metabolism. ATP is generated from the breakdown of CHO, Fats, and Protein Glucose is the primary source of CHO used for ATP production. Cells obtain glucose from the circulation or from stored glycogen. CirculaTory glucose can come from synThesis in The liver, or from digesTed feed. Maximum and minimum blood glucose levels are conTrolled in a small range by insulin/glucagon. Brain cells and R86 can ONLY use glucose as an energy source. Muscular conTracTions during exercise can uTilize glucose aerobically and anaerobically To produce ATP. FaT is The mosT abundanT energy source in The body (100 x GLVCOGEN) and can be uTilized by almosT all body Tissues for energy producTion (aerobic). MosT of The long-chain, free faTTy acids (FFA) used for energy producTion come from sTored body faT. Adipose Tissue is sTimulaTed To release fr/yb/cer/b’es inTo The circulaTion which are used as FFA by The cells. UTilizaTion of FFA for energy is limiTed only by faT sTores and oxygen availabiliTy. VolaTile FaTTy Acids, VFA, originaTe from The fermenTaTion of fiber and can be uTiIized direchy from The circulaTion for energy. Excess VFA can be sTored as glucose (synfhesis in The liver), or as Triglycerides in adipose Tissue. **Horses consuming a dieT of good qualiTy hay can meeT 80% of Their mainTenance energy requiremenT from VFA producTion. ENERGY REQUIREMENTS: MainTenance: Physiological mainTenance = a maTure animal ThaT is noT pregnanT, lacTaTing, growing, or performing work and is in a ThermoneuTral zone. The amounT of dieTary energy required To prevenT a change in The ToTal energy conTained in The body of These animals is considered To be The mainTenance requirement The 2007 NRC provides for Three Types/sTages of mainTenance based on acTiviTy, digesTive efficiency, and possibly body Type. Minimum - 30.3 kcal/kg X BW(kg) Average - 33.3 kcal/kg X 8W 1000-1100# = 16-17 Mcal/day ElevaTed - 36.3 kcal/kg X BW Influence of Environment on Maintenance Requirements: 5 climatic variables - ambient temperature; wind velocity; solar radiation (sunshine); precipitation: and relative humidity. TEMPERATURE - affects evaporative heat exchange (especially HOT) and convection, conduction and radiation (COLD). HUMIDITY — primarily affects evaporation. Horses are homeotherms and must maintain a constant core temperature. He responds to cold or heat through acute or chronic physiological, metabolic and behavioral responses. ACUTE - cold: increased feed consumption: seek shelter; postural changes. Heat: reduce feed intake; sweating; increase respiration; increase water intake; postural changes: seek wind. CHRONIC — cold: longer feeding periods; longer hair coat; decrease peripheral body temperature; decrease respiration. Heat: nocturnal feeding; reduced feed intake; increased frequency of drinking; reduced activity. Body heat production is influenced by feed intake and feed composition. Adjusting the feeding program can assist the horse in coping with cold or heat stress. COLD — increase feed intake, especially forage (forage digestion produces more heat), provide shelter. HEAT - decrease feed intake and/or increase # of feedings/day (smaller portions produce less heat/feeding); provide shade; provide wind. Growth: The energy requirement of a growing horse is the sum of energy needed for maintenance plus the energy needed for gain. DEW“. = (0.565m‘0'145 x BW) maintenance + (1.99 + 1.21m — 0.021m2)X ADG gain Where DE = Mcal/day: m = months of age; ADG = kg/day. DE for maintenance is highest during the 15* 5—6 months of age, declines between 6—12 months, and then declines again from 12—24 months of age. DE for gain increases with age: 6 months : 8.5 Meal/kg of gain; 12 months : 13.5: 18 months : 17; 24 months = 18.9. Ration QUALITY is a priority during growth. Protein: energy ratio; EAA profile; mineral profile; vitamins, etc. Feeding program: select a balanced concentrate that is formulated for the growing horse and compliments the forage. Adjust intake based on growth and body condition. Stallion: Stallions are generally considered to have higher maintenance requirements than geldings or mares. The amount of dietary energy needed during the breeding season will probably be influenced by breeding frequency. Stallions bred/collected < 50 times/season ~100—105% maintenance 50-100 ~ 110% maintenance > 100 ~ 120% maintenance During the non-breeding season, stallions may also have an elevated maintenance requirement due to increased activity. Pregnancy: During pregnancy, energy is used for maintenance of the more, development of the fetus, development of the placenta, development of the mammary system, enlargement of the uterus, and maintenance of the fetus, placenta, mammary and uterine tissue. The greatest percentage of growth occurs during the last trimester of gestation. On average, the mare will gain 15-20% (fetus = ~ 10%) of her BW during gestation to allow for fetal/placental growth and development. Therefore, commonly it is calculated that the pregnant more will need to consume ~ 120% of maintenance. Mares in good body condition (BC$>6) can often produce healthy foals without gaining significant weight. Stored body fat is used as an energy source for development and maintenance of the feto—placental unit. Mares in low body condition (BC$<5) may have prolonged gestations and reduced fertility post—parturition. Lactation: During lactation, energy requirements are the sum of DE utilized for milk production and DE utilized for maintenance. Maintenance of lactating mares is elevated (36.3 kcal/kg BW) due to increased activity associated with maternal behavior and increased feed intake. Milk Production rises rapidly during the 15’ 10 days postpartum, so energy demand increases tremendously immediately after foaling. Almost all mares, even those on very high feed intakes, will LOSE WEIGHT during the 15" week of lactation. Exercise: The amount of energy used during exercise depends on duration and intensity. WORK : weight X distance WORK 2 distance / time (for an individual horse) FACTORS INFLUENCING WORK: >Duration : distance : time >Intensity : Speed Footing (deep sand, grass, shallow arena, etc.) Terrain (uphill, downhill) Jumps, stops, turns, etc. Collection Skill of rider Fitness of horse Daily Energy Requirements include maintenance, daily exercise, and activities assoc/a fed with a performance horse. Hauling: similar to energy used during walking. Lounging: grooming: stable vices Classifications of exercise: LIGHT = 1—3 hours/week; 40% walk, 50% trot; 10% lope Recreational riding: beginning of training: monthly show horse DE (Mcal/day) = maint. X 1.2: good quality forage MODERATE : 3—5 hours/week: 30% walk, 55% trot, 10% lope, 5% maneuvers School horses: recreational riding; increased training: weekly show horses: cutting: polo: roping: barrels DE = maint. X 1.4; grass hay plus alfalfa HEAVY = 4-5 hours/week: 20% walk, 50% trot, 15% lope, 15% gallop and strenuous skills Ranch work: high level polo, cutting, reining, etc; show horses more than 1/week; low/mod eventing; early/mid race training DE = maint. X 1.6; need concentrate VERY HEAW : INTENSE : 6—12 hours/week: speed work, long slow distance work, strenuous skills Racing; endurance; 3-day eventing DE : maint. X 1.9; need fat added concentrate FEEDING FOR ENERGY: Every horse has a total need for energy. Nutrients actually used for maintenance and production comes from energy stored in the body - blood glucose, glycogen, circulating VFA's, and body fat. Feeding management: 1. Feed program > Forage/roughage quality > Feeding schedule - # feedings/day 2. Energy needs > Maintenance — good quality forage > Performance Intensity - strength vs. endurance Strength needs glucose/glycogen Anaerobic Endurance needs FFA Aerobic Feed selection: > Good quality grass hay 9 0.8—0.9 Mcal DE/# > Alfalfa 9 0.9-1.2 Mcal DE/# P Traditional concentrates (3-3.5‘70 CFat) 9 1.25 Mcal DE/# ‘; Fat Added (6% CFat) 9 1.45 Mcal DE/# 0 Benefit = glycogen sparing effect GROWTH: Feeding growing horses and pregnant mares requires a high quality diet with proper protein/energy ratios. Quality : Protein/energy; EAA profile; proper vitamins and minerals ...
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