Download - ENERGY BALANCE AND SYSTEMS
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ENERGY BALANCE AND SYSTEMS
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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
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Basics of Energy Use in Mammals
• Simple
• Practical– Energy systems to predict and monitor livestock
production– The common thread among human weight loss
systems
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ENERGY CONCEPTS
• Energy - “ability to do work”
• Feedstuffs– protein– carbohydrates– lipids
• Physics of energy– Priestly 1700’s - the flame and the mouse
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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.
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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
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Hess’ Law of Heat Summation
FEED ANIMALFECES
URINE
GAS
HEAT
MAINTENANCE
PRODUCTION
100% OF
ENERGY
INTAKE
1. Not concerned with mechanisms or rates of energy change
2. True for living as well as non-living systems
3. Forms basis for bioenergetic investigation even if mechanisms of action is unknown
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ATP-ADP CYCLE
CATABOLISM
MECHANICALWORK
TRANSPORTWORK
BIOSYNTHETICWORK
CO2
H2O
FUELS
O2
Pi
Pi
Pi
ADP ATP
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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
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PARTITIONING OF ENERGY
Gross Energy (GE)
Digestible Energy (DE)
Metabolizable Energy (ME)
Net Energy (NE)
Digestion loss (fecal)
Urine lossCombustible gases (CH4)
Heat increment (HI)-heat of fermentation-heat of nutrient metabolism
NEm-basal metabolism-activity at maintenance-sustaining body temp
NEg-retained energy
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HEAT LOSS
•BASAL METABOLISM
•VOLUNTARY ACTIVITY
•PRODUCT FORMATION
•THERMAL REGULATION
•WORK OF DIGESTION
•HEAT OF FERMENTATION
•WASTE FORMATION AND EXCRETION
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BASAL METABOLISM
•VITAL CELLULAR ACTIVITY
•RESPIRATION
•BLOOD CIRCULATION
•IONIC BALANCE
•TURNOVER OF PROTEINS
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RETAINED ENERGY
•TISSUE GROWTH
•LACTATION
•WOOL GROWTH
•HAIR GROWTH
•PREGNANCY
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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
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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
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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
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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
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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
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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)
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Body Size and Metabolism
Kleiber
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Armsby Calorimeter
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Determination of Nem of timothy hay by a difference trial
Feedinglevel
Feedeaten(lb)
ME intake(kcal)
Heat prod.(kcal)
Energygain(kcal)
1 6.2 5788 8062 -2296
2 10.2 9544 9812 -268
Diff. 4.0 3766 1748 2028
Armsby (1922) NEm = 2028/4 = 51 Mcal/cwt
Of historical importance:
1. H = ME - P
2. Development of comparitive slaughter technique
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Lofgreen and Garrett (1968)
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NEm DETERMINATION
Alfalfa High Item Hay Concentrate
Intake at Equilibrium 35 23Heat Prod. an No Feed 43 43NEm of the Feed (kcal/g) 1.23 1.87
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NEp BY THE "DIFFERENCE TRIAL"
+
0
ENERGYGAIN
NEp
FEED INCREASE
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ACTUAL "DIFFERENCE TRIAL" ON
HIGH CONC. RATION
Level of FeedingItem Equilibrium Free ChoiceFeed Intake 23 59Energy Gain 0 40
Differences:Feed Intake, g -- 36Energy Gain, kcal -- 40
NEp of Feed:kcal per gram -- 1.11
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Comparison of Fed and Fasted Steers by Indirect calorimetry (“head box”)
Fed Fasted
Weight (kg) 339 333
Gas exchange (1/2 h):
Oxygen 197.2 131.0
Carbon dioxide 198.8 96.1
Methane 8.2 1.0
RQ 1.01 0.73
Heat Production
kJ/d per kg BW 147.3 93.7
jJ/d per kg BW0.75 632.6 400.8
Eisemann and Nienaber (Brit. J. of Nutr. 64:399, 1990)
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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
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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
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EFFECT OF ENVIRONMENT ON
ENERGY REQUIREMENTS
EFFECTIVE AMBIENT TEMPERATURE
THERMONEUTRALZONE
Low High
Heat StressCold stress
OptimumforPerformanceand Health
LowerCriticalTemperature
UpperCriticalTemperature
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Lower Critical Temperature
•Coat Description LCT
•Summer or wet 59
•Fall 45
•Winter 32
•Heavy winter 18
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Effective Temperature
TemperatureWind Speed -10 0 10 20 30Calm -10 0 10 20 305 -16 -6 3 13 2315 -25 -15 -5 4 1430 -46 -36 -26 -16 -6
*Maintenance Requirements increase .7% for each degreeof cold stress.
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NEp (production)
•NEg (gain)
•NEc (conceptus)
•NEl (lactation)
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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
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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 6.0Corn 7 .85 5.95SBM 1.5 .9 1.35
Total 23.5 13.3
X =
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Step 2. Determine NEm intake
Lb. DM NEm/lb NEm(Mcal)
Corn silage 6 .4 4.44Corn 5.95 1.02 6.07SBM 1.35 .93 1.26
Total 13.3 11.77
Ration NEm (DM Basis) = 11.77Mcal/13.3 lb DM = .89 Mcal/lb
X =
Using Net Energy for Gain Projection
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Using Net Energy for Gain Projection
Step 3. Determine NEg intake
Lb. DM NEg/lb NEg(Mcal)
Corn silage 6 ..47 2.82Corn 5.95 .70 4.17SBM 1.35 .63 .85
Total 13.3 7.84
Ration NEg (DM Basis) = 7.84Mcal/13.3 lb DM = .59 Mcal/lb
X =
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Using Net Energy for Gain Projection
Step 4. Determine Lb of DM for maintenance
1. NEm requirement 500 lb. steer = 4.5 Mcal4.5 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 inopen lot conditions in November in Iowa.
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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.
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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
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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 of feeding
•For a comparison of Dairy Energy Systems see:
J Dairy Sci 81:830, 840, 846 (1998) Energy Symposium
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Dairy NRC Feed Energy Discounts
00.5
11.5
22.5
33.5
44.5
60 65 70 75 80
Maintenance TDN
Uni
t d
eclin
e p
er m
ulti
ple
of
Mai
nt
= .18 X -10.3
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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 1401 .070 .145 .2602 .125 .265 .4403 .170 .345 .570
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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
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Maintenance Requirements
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Factors affecting Maintenance
• Weight
• Physiological State
• Acclimatization
• Sex
• Breed
• Activity
• Heat or Cold stress– External Insulation
• Coat Condition
• Wind speed
• Hide Thickness
– Internal Insulation
• Condition Score
• Age
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Base NEm Requirement
• 77 kcal / (BWkg)0.75
• Adjusted for:– Acclimatization– Sex– Breed– Physiological state
• Lactation
• Condition Score
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Effect of Condition Score on Maintenance Requirement
80%
85%
90%
95%
100%
105%
110%
115%
120%
1 2 3 4 5 6 7 8 9
Condition Score (1-9 scale)
Mai
nte
nan
ce M
ult
ipli
er
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Energy Requirements vs. Body Weight
0.00
2.00
4.00
6.00
8.00
10.00
12.00
0 200 400 600 800
Body Weight
NE
m R
equ
ired
, Mca
l/d
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Energy Requirements vs. Previous Temp.
50
60
70
80
90
100
110
-20 -10 0 10 20 30 40
Previous Temperature, OC
NE
m R
equ
ired
, M
cal/
BW
0.75
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Effect of Breed on Energy Requirements
90%100%
120%
0%
20%
40%
60%
80%
100%
120%
Bosindicus
Bos taurus Dairybreeds
Rel
ativ
e N
Em
Req
uir
ed
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Effect of Lactation on Energy Requirements
100%
120%
0%
20%
40%
60%
80%
100%
120%
Non-lactating
Lactating
Rel
ativ
e N
Em
Req
uir
ed,
% o
f B
asal
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Maintenance Adjustment for Grazing(based on a 600 kg cow)
100%
110%
120%
130%
140%
150%
160%
0.25 0.75 1.25 1.75
Forage Availability (T/ha)
Mai
nen
ance
Ad
just
men
t
Level
Hilly
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Estimation of Heat Production and Calculation of Lower Critical Temp (LCT)
• Calculate Feed for Maintenance (FFM)– NEm Req./ NEm Diet = FFM
• Calculate Feed for Production (FFP)– DMI - FFM = FFP
• Calculate Net Energy of Production (NEP Tot)
– NEP Diet x FFP = NEP Tot
– For growing & finishing; NEP Diet = NEg Diet
– For other animals; NEP Diet = NEm Diet
• Calculate Heat Production (HP)– MEIntake - NEP Tot = HP, Mcal
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Body Surface Area vs. Body Weight
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
0 200 400 600 800
Body Weight
Su
rfac
e A
rea,
M2
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Effect of Condition Score on Internal Insulation
0
2
4
6
8
10
12
14
1 2 3 4 5 6 7 8 9
Condition Score (1-9 scale)
Inte
rnal
Insu
lati
on
,
Mca
l/M2 /O
C/d
<30
30-183
184-364
>365
Age, d
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Effect of Wind Speed and Coat Condition on External Insulation
0
5
10
15
20
25
0 5 10 15 20 25 30
Wind Speed, kph
Ext
ern
al In
sula
tio
n,
Mca
l/M2 /O
C/d
Clean & Dry some mud on lower body
mud on lower body and sides heavily covered with mud
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Effect of Wind Speed and Hide Thickness on External Insulation
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30
Wind Speed, kph
Ext
ern
al In
sula
tio
n,
Mca
l/M2 /O
C/d
Thin Hide Medium Hide Thick Hide
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Effect of Wind Speed and Hair Depth on External Insulation
05
101520253035404550
0 5 10 15 20 25 30
Wind Speed, kph
Ext
ern
al In
sula
tio
n,
Mca
l/M2 /O
C/d
1 cm 2 cm 3 cm
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Estimation of Heat Production and Calculation of Lower Critical Temp (LCT)
Calculate Heat Loss (HL)– HL = HP / SA, Mcal/M2
Calculate Total Insulation (TI)– TI = EI + II, Mcal/M2/OC/d
Calculate Lower Critical Temp (LCT)– LCT = 39 - (HL x TI), OC
Calculate Heat Production– MEIntake - NEP Tot = Heat Production
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Energy Requirements vs. Current Temp.
0
1
2
3
4
5
6
7
-30 -20 -10 0 10 20 30 40
Current Temperature, OC
Ad
dit
ion
al M
E
Req
uir
ed,
Mca
l/d
LCT = 5
LCT = -5
Assumed SA = 6 M2
and TI = 28 Mcal/M2/OC/d
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Environmental Effects on Maintenance RequirementsBeef Cow Wintering Ration (hay @ .90 mcal ME/lb DM)
Hair Coat Code at30oF
Hair Coat Code at10oF
1 3 1 3
HideCode
Wind @ 1 mph
1 1.19 1.19 1.29 1.682 1.19 1.19 1.29 1.553 1.19 1.19 1.29 1.45
Wind @ 10 mph
1 1.22 1.48 1.60 1.942 1.19 1.41 1.47 1.843 1.19 1.34 1.36 1.75
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Environmental Effects on Maintenance RequirementsTypical Calf Wintering Ration ( .35 mcal NEg/lb DM)
Hair Coat Code at30oF
Hair Coat Code at10oF
1 3 1 3
HideCode
Wind @ 1 mph
1 1.19 1.47 1.50 2.932 1.19 1.37 1.36 1.803 1.19 1.28 1.29 1.69
Wind @ 10 mph
1 1.41 1.69 1.85 2.202 1.30 1.61 1.71 2.103 1.21 1.54 1.60 2.01
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Environmental Effects on Maintenance RequirementsTypical Finishing Ration ( .62 mcal NEg/lb DM)
Hair Coat Code at30oF
Hair Coat Code at10oF
1 3 1 3
HideCode
Wind @ 1 mph
1 1.19 1.19 1.33 1.762 1.19 1.19 1.29 1.633 1.19 1.19 1.29 1.51
Wind @ 10 mph
1 1.24 1.52 1.67 2.032 1.19 1.44 1.54 1.933 1.19 1.36 1.42 1.83
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Growth Requirements
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Factors we must account for to predict NEg required in North America
• Genotype - over 80 types have been identified• Sex
– Feedlot steers, heifers & bulls
– Replacement heifers
– Bulls
– Cows
• Implant combinations• Feeding systems
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Relationship between Body Fat & Grade
Marbling % Body USDA CanadianScore Fat Grade Grade
Trace 25.2% Standard A1Slight 26.8% Select A2Small 27.8% Choice A3
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NEg Required for Growth
0
1
2
3
4
5
6
7
8
200 250 300 350 400 450 500
Shrunk Body Weight, kg
NE
g M
cal/
d
0.6 kg/d
1.0 kg/d
1.3 kg/d
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% Protein in Gain vs. Rate of Gain
0
5
10
15
20
25
200 250 300 350 400 450 500
Shrunk Body Weight, kg
% P
rote
in i
n G
ain
0.6 kg/d
1.0 kg/d
1.3 kg/d
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% Fat in Gain vs. Rate of Gain
0
10
20
30
40
50
60
70
80
90
200 250 300 350 400 450 500
Shrunk Body Weight, kg
% F
at i
n G
ain
0.6 kg/d
1.0 kg/d
1.3 kg/d
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Shrunk Body Fat
10
12
14
16
18
20
22
24
26
28
30
200 250 300 350 400 450 500
Shrunk Body Weight, kg
% S
hru
nk
Bo
dy
Fat
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Body Fat vs. Shrunk Body Weight
10
12
14
16
18
20
22
24
26
28
30
200 250 300 350 400 450 500
Shrunk Body Weight
% B
od
y F
at
Traces
SmallSlight
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Birth to Maturity - Protein Composition
0
2
4
6
8
10
12
14
16
18
20
0 200 400 600 800 1000
Shrunk Body Weight, kg
% P
rote
in i
n G
ain
0
20
40
60
80
100
120
Em
pty
Bo
dy
Pro
tein
, kg
%PIG
EBP,kg
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Birth to Maturity - Fat Composition
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Shrunk Body Weight, kg
% F
at i
n G
ain
0
100
200
300
400
500
600
700
Em
pty
Bo
dy
Fat
, kg
%FIG
EBF,kg
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5%
15%
25%
100 300 500 700 900
Empty body weight, kg
Em
pty
bo
dy
fat,
%
1 = Angus heifer2 = Holstein heifer3 = Angus steers4 = Holstein steers5 = Angus bulls6 = Holstein bulls
1 2 3 4 5 6
Non-implanted cattle of Fortin et. al., 1980 Non-implanted cattle of Fortin et. al., 1980 (50 heifers, 37 steers and 54 bulls)(50 heifers, 37 steers and 54 bulls)
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Calculation of Equivalent Weight
Actual BW x (SRW / FW) = EQSW
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Calculation of Retained Energy
RE = 0.0635 x EBW0.75 x EBG1.097
RE = 0.0635 x EQEBW0.75 x EBG1.097
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Calculation of Daily Gain
SWG = 13.91 x RE0.9116 x SBW-0.6837
SWG = 13.91 x RE0.9116 x EQSBW-0.6837