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ENERGY BALANCE AND SYSTEMS. References. Blaxter, K. L. 1989. Energy Metabolism in Animals and Man. Cambidge University Press Kleiber, M. 1975. The Fire of Life. Krieger Publishing, New York Also Beef, Dairy, and Sheep NRC. Basics of Energy Use in Mammals. Simple Practical
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References • Blaxter, K. L. 1989. Energy Metabolism in Animals and Man. Cambidge University Press • Kleiber, M. 1975. The Fire of Life. Krieger Publishing, New York Also Beef, Dairy, and Sheep NRC
Basics of Energy Use in Mammals • Simple • Practical • Energy systems to predict and monitor livestock production • The common thread among human weight loss systems
ENERGY CONCEPTS • Energy - “ability to do work” • Feedstuffs • protein • carbohydrates • lipids • Physics of energy • Priestly 1700’s - the flame and the mouse
Priestly and the discovery of oxygen A candle or an animal can make good air bad. Plants restore to the air whatever breathing animals and burning candles remove.
Early discoveries of relevance • Theory of combustion - Both fire and animals produce the same amount of heat per unit of CO2 • Heat production /unit of O2 produced is a more uniform measurement • 1st law of thermodynamics - energy cannot be created or destroyed
Hess’ Law of Heat Summation • Not concerned with mechanisms or rates of energy change • True for living as well as non-living systems • Forms basis for bioenergetic investigation even if mechanisms of action is unknown FECES URINE GAS HEAT MAINTENANCE PRODUCTION FEED ANIMAL 100% OF ENERGY INTAKE
CO2 ATP-ADP CYCLE FUELS H2O O2 CATABOLISM ADP ATP Pi MECHANICAL WORK Pi TRANSPORT WORK Pi BIOSYNTHETIC WORK
Units of Measure • Calorie - energy required to raise the temperature of 1 g of water 1 degree C (from 16.5 to 17.5) • 1 kilocalorie (kcal) = 1,000 calories • 1megacalorie (Mcal) = 1,000,000 calories • 1kcal/g = 1 Mcal/kg • 1 calorie = 4.184 joules
PARTITIONING OF ENERGY Gross Energy (GE) Digestible Energy (DE) Metabolizable Energy (ME) Net Energy (NE) Digestion loss (fecal) Urine loss Combustible gases (CH4) Heat increment (HI) -heat of fermentation -heat of nutrient metabolism NEm -basal metabolism -activity at maintenance -sustaining body temp NEg -retained energy
HEAT LOSS • BASAL METABOLISM • VOLUNTARY ACTIVITY • PRODUCT FORMATION • THERMAL REGULATION • WORK OF DIGESTION • HEAT OF FERMENTATION • WASTE FORMATION AND EXCRETION
BASAL METABOLISM • VITAL CELLULAR ACTIVITY • RESPIRATION • BLOOD CIRCULATION • IONIC BALANCE • TURNOVER OF PROTEINS
RETAINED ENERGY • TISSUE GROWTH • LACTATION • WOOL GROWTH • HAIR GROWTH • PREGNANCY
SYNTHESIS OF BODY TISSUES • FAT contains 9.4 Mcal/kg and 3.8 Mcal/kg is lost as heat • 13.2 Mcal are required to deposit 1 kg fat • PROTEIN contains 5.6 Mcal/kg (muscle=1.1 Mcal/kg) • 7.4 Mcal are lost as heat (1.5 Mcal for muscle) • 13 Mcal are required to deposit 1 kg of protein • 2.6 Mcal are required to deposit 1 kg of muscle
GROSS ENERGY • FEED GE (kcal/g) • Corn meal 4.4 • Oats 4.6 • Wheat bran 4.5 • Timothy hay 4.5 • Clover hay 4.5 • Corn stover 4.3 • Oat straw 4.4
GROSS ENERGY OF FEEDSTUFF COMPONENTS • CARBOHYDRATE 4.2 kcal/g • FAT 9.4 kcal/g • PROTEIN 5.6 kcal/g • ASH 0.0 kcal/g BACON TORCH
Calorimetry • DIRECT - direct measurement of heat production • INDIRECT - calculation of heat production from O2 intake, CO2 release and methane and nitrogen losses • HE = 3.886 02 +1.2 CO2 -.518 CH4-1.231N
Nitrogen Carbon Balance (Indirect) • Required data: dry matter, nitrogen, carbon and energy of feed, feces, urine, methane and carbon dioxide. • Assumed: • 6 g protein/g N • .5254 g carbon/g. protein • 5.6 kcal/g protein
N-C balance cont’ • Carbon gained as fat = Foodc – (Fecesc + Urinec + CO2c + Methanec + Proteinc) • Fat assumptions: • 1.307 g fat/ g carbon • 9.4 kcal/g fat • Heat productionkcal = Intakekcal - (Feceskcal + Urinekcal + Methanekcal +Protein gainedkcal + Fat gainedkcal)
Body Size and Metabolism Kleiber
Determination of Nem of timothy hay by a difference trial Armsby (1922) NEm = 2028/4 = 51 Mcal/cwt Of historical importance: 1. H = ME - P 2. Development of comparitive slaughter technique
NEm DETERMINATION Alfalfa High Item Hay Concentrate Intake at Equilibrium 35 23 Heat Prod. an No Feed 43 43 NEm of the Feed (kcal/g) 1.23 1.87
NEp BY THE "DIFFERENCE TRIAL" ENERGY GAIN NEp + 0 FEED INCREASE
ACTUAL "DIFFERENCE TRIAL" ON HIGH CONC. RATION Level of Feeding Item Equilibrium Free Choice Feed Intake 23 59 Energy Gain 0 40 Differences: Feed Intake, g -- 36 Energy Gain, kcal -- 40 NEp of Feed: kcal per gram -- 1.11
Comparison of Fed and Fasted Steers by Indirect calorimetry (“head box”) Eisemann and Nienaber (Brit. J. of Nutr. 64:399, 1990)
DIGESTIBLE ENERGY (DE) • TOTAL DIGESTIBLE NUTRIENTS (TDN) • 1 lb TDN = 2,000 kcal DE • TDN = DCP + DNFE + DCF + 2.25(DEE) • Estimated from ADF • from truly digestible NFC, NDF, CP and FA • Dairy NRC • (http://www.nap.edu/books/0309069971/html/) • pp. 13-27
CONVERSION BETWEEN DE, ME & NE • ME = .82DE • NEm = 1.37 ME - 0.138 ME2 + 0.0105 ME3 -1.12 • NEg = 1.42 ME - 0.174 ME2 + 0.0122 ME3 -1.65
EFFECT OF ENVIRONMENT ON ENERGY REQUIREMENTS Lower Critical Temperature Upper Critical Temperature THERMONEUTRAL ZONE Cold stress Heat Stress Optimum for Performance and Health High Low EFFECTIVE AMBIENT TEMPERATURE
Lower Critical Temperature • Coat Description LCT • Summer or wet 59 • Fall 45 • Winter 32 • Heavy winter 18
Effective Temperature Temperature Wind Speed -10 0 10 20 30 Calm -10 0 10 20 30 5 -16 -6 3 13 23 15 -25 -15 -5 4 14 30 -46 -36 -26 -16 -6 *Maintenance Requirements increase .7% for each degree of cold stress.
NEp (production) • NEg (gain) • NEc (conceptus) • NEl (lactation)
Beef NRC Gain equations • NEm (Mcal) = .077 WTkg.75 *(environmental adjustment) • EBW = .891 SBW • EBG = .956 SWG • SRW = 478 kg for animals finishing at small marbling • EQSBW = SBW * (SRW)/(FSBW) • EQEBW = .891 EQSBW • RE = 0.0635 EQEBW0.75 EBG1.097 • SWG = 13.91 RE 0.9116 EQSBW-.6837
Using Net Energy for Gain Projection Step 1. Determine dry matter intake of each ingredient Lb. as fed DM fraction Lb DM Corn silage 15 .4 6.0 Corn 7 .85 5.95 SBM 1.5 .9 1.35 Total 23.5 13.3 = X
Using Net Energy for Gain Projection Step 2. Determine NEm intake Lb. DM NEm/lb NEm (Mcal) Corn silage 6 .4 4.44 Corn 5.95 1.02 6.07 SBM 1.35 .93 1.26 Total 13.3 11.77 = X Ration NEm (DM Basis) = 11.77Mcal/13.3 lb DM = .89 Mcal/lb
Using Net Energy for Gain Projection Step 3. Determine NEg intake Lb. DM NEg/lb NEg (Mcal) Corn silage 6 ..47 2.82 Corn 5.95 .70 4.17 SBM 1.35 .63 .85 Total 13.3 7.84 = X Ration NEg (DM Basis) = 7.84Mcal/13.3 lb DM = .59 Mcal/lb
Using Net Energy for Gain Projection Step 4. Determine Lb of DM for maintenance 1. NEm requirement 500 lb. steer = 4.5 Mcal 4.5 Mcal * environmental adjustment (1.3) = 5.85 Mcal required / .89 Mcal NEm per lb of DM = 6.6 lb. of feed dry matter needed for maintenance Environmental adjustment (maintenance ratio) for calf fed in open lot conditions in November in Iowa.
Using Net Energy for Gain Projection Step 5. Determine energy available for gain 1. 13.3 lb DM intake - 6.6 lb (needed for maintenance) = 6.7 lb. of feed DM available for gain. 2. 6.7 lbs of DM X .59 Mcal/lb (NEg) = 3.95 Mcal available for gain.
Using Net Energy for Gain Projection • Step 6 - Determine weight gain • 227 kg steer (low choice at 500 kg) • EQSBW = 227 * (478/500) = 217 kg • SWG = 13.91 * 3.95 0.9116 * 217 -.6837 = 1.23 kg/d • ADG = 1.23*2.205 = 2.71 lb/day
Energy Calculations for Dairy Cattle • NEm = .08 LW.75 - increased for activity • Growing bulls & heifers have 12% higher req than beef • NEm = .086 LW.75 • or use beef equations and increase Maint 7-10% • NEl~NEm because of similar efficiency • Lactation requirement (Mcal/kg) milk • = .0969(percent fat in milk)+.36 • Feed Energy Values discounted for level offeeding • For a comparison of Dairy Energy Systems see: J Dairy Sci 81:830, 840, 846 (1998) Energy Symposium
Dairy NRC Feed Energy Discounts = .18 X -10.3
Energy calculations for Sheep • Maintenance requirement is lower than beef • .056 W.75 • Wool has great insulative value • Fetal number is important (Nep, Mcal/day) Stage of gestation (days) #fetuses 100 120 140 1 .070 .145 .260 2 .125 .265 .440 3 .170 .345 .570
1996/2001 Beef NRC Model Objectives: • Predict net energy requirements across a continuum of cattle types • Adjust requirements for physiological state • Adjust requirements for environmental conditions • Predict variable lactation requirements • Predict energy reserves fluxes • Describe feeds by fermentation characteristics • Describe rumen and animal tissue N requirements • Compute variable ME and MP from feed analysis • Two levels of solution
Weight Physiological State Acclimatization Sex Breed Activity Heat or Cold stress External Insulation Coat Condition Wind speed Hide Thickness Internal Insulation Condition Score Age Factors affecting Maintenance
Base NEm Requirement • 77 kcal / (BWkg)0.75 • Adjusted for: • Acclimatization • Sex • Breed • Physiological state • Lactation • Condition Score