TITLE
REVIEW : ENERGY EQUATION IN RUMINANT NURITION
Muhamad Nasir Rofiq (Doctorate Student, Anmal Science
Departement,
Institute of
Applied Science, Cukurova University)
This paper provides summative energy equation of ruminant nutrition and applies it to estimate the energy value of feed. Energy is the primary nutrient contributed by feed (TMR, forage and concentrate feed) . Some equation was developed using chemical compound (proximate analyzed or carbohydrate and protein fraction), digestibility experiment, rumen gas fermentation experiment and combined analyzed. Energy equation also was separated to classes such as forage, concentrate, animal source, fat feed and fatty acid. Specially for this paper is giving information about energy equation in ruminan nutrition by feed proximate fractionation, feed CNCPS fractionation, in vitro rumen gas fermentation, and in vitro rumen digestibility.
Feed is generally the major operating cost associated
with livestock and ruminant operations. Over feeding situation is wasteful
while underfeeding will decrease performance and profitability. Optimum feeding of animals is obtained by
good formulated feed which was contains nutrients enough and bio availabililty.
To obtain good formulated feed, nutrient contain of feeding stuff should be meet to animal nutrient
requirement. Nutrient in feeding stuff as chemical compound were analyzed at
laboratory as procedure. But nutrient requirement f animal should be analyzed
by bio research. Recently the result from chemical compound of feed and bio
research could be use as mathematic formulation to estimate nutrient
requirement and nutrient quality.
Feeding
stuffs of ruminant has high variety physical and chemical properties. It made
high variety nutritive value for some of feeding stuffs (forages, by product,
and some animal meals). The variety was caused by agronomic characteristics,
sampling, geographic, and processing of feedstuffs. Their data were recorded well
in nutrient list feed table. In feeding stuff tables, chemical and nutritive
data are reported as well as some brief information to characterize the feed
(NRC, 1982, 2001; INRA, 1980, 1988, FAO, 2012).
The fundamental characteristic of formulated rations for ruminant around which all other nutrients are
structured, is its energy content. Its level energy in formulated ration is the
sum of energies in its component feeds, but it cannot be analyzed as it
represents the potential of feed, and its components, to do work as biological
products, such as meat or milk or as heat. Recently accurate knowledge of the
energy content of feeds is central to formulation of rations, which will
maximize animal output of usable products, and minimize output of unused
nutrients (i.e.waste , heat and gas). It could be estimated by bio experiment
which its result is mathematic formulation as an equation to estimate their
content.
The purpose of this
article is to review some energy equation
in ruminant nutrition was resulted by some researches and applies to
TMR, alfalfa hay and concentrate feed using data of chemical of feed, in vitro
gas fermentation and in vitro true digestibility.
FEED
CHEMICAL COMPOUND
The nutritive value of a feed is determined by the
contribution it is able to make to nutritional requirements (energy, protein,
and mineral) of the class of animal. Feed Analysis, most commercial
laboratories offer standard feed test for forages, grain, or total mixed
rations. Chemical nutrient Analyses in
feed mostly for proximate analyze and van soest analyze to determine moisture,
Crude protein, Extract ether, crude fiber, ADF and NDF is recommended when
designing diets for ruminant. Furthermore we may wish to identify key mineral
or minor nutrient interest. We should also know gross energy in feed
analyzed by bomb calorimeter.
Typically, results are reported on as fed and dry matter basis. After
formulation with dry matter basis for nutrient balanced, values convert to an
as fed basis. The result can estimate energy value of feed and digestibility.
The original system for analyzing feeds, the Weende
system of Proximate analysis was developed in the 1860s by Henneberg and
Stohman at the Weende Experimental station in Germany. Their method was to
separate feed into the nutrient components needed by the animal. That is water,
crude protein, crude fat or ether extract, ash or mineral matter, crude fiber,
the indigestible fraction of the carbohydrates present and nitrogen free
extract (NFE) the readily digestible carbohydrate fraction. The substantial
amount of crude fiber (CF) where as much of the NFE in some feeds is not
digested. This problem prompted van soest in 1963, to develop his system of
detergent fiber analysis which determine lignin the totally indigestible
fraction of ruminant feeds as separate entity (figure 1).
Inter fractionation of feed chemical nutrient between
proximate system and detergent system (van soest) explain relation between
their nutrient and substitute nutrient value each other (Figure 2). For further
analysis, especially for energy source from carbohydrates estimated by carbohydrates
fractionation analysis was supported by data analyzed.
Figure
2. inter fractionation of chemical feed analysis between proximate and Van
soest
Figure
3. Classification of forage fraction using van soest method
Figure
4. Fractionation of plant carbohydrates
Recently, there is updated system for feed analysis which
was used carbohydrate and protein data of feed. The system was the net
carbohydrate and protein system (CNCPS) which was developed by Cornell
University Nutrient managmen Planning System (UCD). The system was classified
feed chemical into 8 components :
1. Dry
matter (DM),
2. ash,
3. Estract ether (EE),
4. Neutral detergent fiber (NDF) and Acid detergent Lignin (ADL),
5. Total crude protein (CP),
6. Soluble protein (SCP),
7. Neutral detergent insoluble CP (NDICP) and Acid detergent insoluble CP (ADICP),
8. Non structural carbohydrate (NSC)
The CNCPS feed
evaluation system data could be used for energy estimation using some equation
which was developed combine with other data (in vitro digestibility or in vivo
digestibility).
Figure 5. The CNCPS
scheme for feed carbohydrate fractionation
(Modified
from Sniffen et al., 1992 in CNCPS ver 3. Manual and references, 2003)
Figure 6. The
CNCPS scheme for Protein fractionation
(Modified from Roe et al., 1990 in CNCPS ver 3. Manual and references,
2003 )
The energy in feed is a measure of that feed’s ability to help the animal function and be productive. All feed have a gross energy value. Some of the gross energy (GE) is lost in feces. Some are absorbed by animal as digestibility energy (DE). From DE, some of them lost in urine, gas and heat to provide metabolisable energy (ME) to animal. The ME was used to maintenance, milk production, keep condition, activity, pregnancy and growth (Figure 7).
The ME is energy available for ruminant
as feed quality indicator.
Figure 7. The flow and
partitioning of dietary energy through the ruminant (Moran, J. 2005)
Energy
can come from various part of the feed. Carbohydrates, fats, oils and even
protein can provide energy.
Soluble carbohydrates
are the simple or individual sugar found in cells of growing plants. They are
digested and used almost instantly by the microbes in the rumen. Soluble
carbohydrates are digested 100 times faster than storage carbohydrates. Storage
carbohydrates are made up of sugar subunits which are chemically bound together
and are found inside plant cells. Starch in example of a storage carbohydrates.
Storages carbohydrates are digested 5 times faster than structural
carbohydrates,. It is founded in grains, leaf, stem and in the bulbous roots of
fodder crop. Structural carbohydrates are fibrous components of plant cell
walls. They provide the structural support that plants need to grow upright.
Pectin, hemicelluloses and cellulose are all structural carbohydrates. Lignin
and silica are often associated with structural carbohydrates in plants. They
give structural support toplants but are indigestible and are not actually
carbohydrates. The can bind the structural carbohydrates and make them less
digestibility.
Fats
and Oils, only 2% until 3% of forages are fat or
oil. Fats and oils include vegetable oils and animal fat and processed fat. Fat
can decrease the palatability of the diet and can coat fiber, interfering with
its digestion by rumen microbes.
Protein,
the rumen microbes can use a surplus of protein in the rumen fro energy. This
is, however and inefficient use of protein. (Semua sumber energy diatas dikasih
contoh dan berapa jumalh energinya).
Energy
as feed quality indicator can be
measured to three measurement, they are digestibility, metabolisable energy(ME)
and total digestibility nutrient (TDN). Digestibility
relates to the proportion of feed which is not excreted in the feces and so is
available for use by ruminant. It is not direct measure of energy, but it does
indicate overall feed quality. It is commonly measured as a percentage. The
digestibility of various feed constituents can be determined with Organic
Material Digestibility (OMD) as percentage of digestible organic matter per
total dry weight. Metabolisable energy
content of a feed also called its energy density is measured as megajoules of
ME per kilogram of dry matter (MJ /Kg DM), or Megacalories per kilogram of dry
matter (Mcal/Kg DM). the intake of ME is expressed in MJ/day or Mcal/day. Total
Digestible Energy (TDN) is an older energy system used in USA and some
countries. It is not used formally in Australia and England. It is a less
accurate measurement of energy than ME. It
does not take into account energy loss via gas (methane,) and urine. TDN expressed as an percentage,
with total digestible nutrients intake expressed in Kg/day.
THE PROBLEM FOR ENERGY ESTIMATION
Prediction of energy availability from laboratory analyses usually requires specific equations for each type of feed. The accuracy of energy estimation is a function of the accuracy of laboratory analyses and the accuracy of the bio experimentation used to develop estimation equation. Digestibility and energy value can be measured under a variety of conditions that influence the resulted values. Cattle, sheep and dairy cows will obtain different digestibility for the same feed.
In
addition,the level of feed intake
has a significant effect on digestibility and the utilization of its energy.
Major variable affecting the measurement of digestibility is the amount of
selection allowed by the animal. They have difference feed preferences. However,
most scientist measure ad libitum intake and digestibility in the same trial by
offering the animals 5 – 15 % more than they consume. Others problem is that the botanical description of feedstuffs and
time of year that it was harvested for forage. They have difference
nutrient value, so that they have difference equation for estimation energy
availability. Type of feed processing
was obtained from industrial waste or agricultural industrial also effect on
feed nutrient value and digestibility.
ESTIMATION
ENERGY IN RUMINANT NUTRITION
Basic Principle for estimation of available energy and digestibility is estimated from chemical composition and bio experiment. There were two factors that determine the energy value of feedstuff for ruminant are its content of fat, due to its high energy value, and the digestibility of its structural fibre (i.e. NDF), due to its generally high content in forage. Most energy values are predicted from fiber analyses because fiber is negatively related to the animal’s ability to digest and use nutrient in the feed.
The
traditional and still most common, approach to estimating the energy value of
feedstuff has been to calculate its
total digestible nutrient (TDN) level using a factorial equation based upon
analyzable component of feedstuffs. Many equation calculate TDN as the sum of
digestible crude protein (CP), digestible fat (multipled by 2.25), digestible
neutral detergent fiber (NDF) and digestible non-structural carbohydrate (NSC)
all corrected for a metabolic cost of digestion by the animal. The estimated of
TDN can be used to estimate the digestible energy (DE), metabolisable energy
(ME) and/or NEl values of individual feedstuffs.
|
TDN%
= Digestible CP + Dig.CF + Dig. Nitrogen free extract (NFE) + Dig.fat x
2.2.5
|
Some Estimation Energy from Chemical compound of Feed
Some
energy estimation were approached using chemical compound (Table ). The some of variables used in the equation
was indicate the correlation between the variable and energy balue (ME, TDN ,
NEl, etc).
Table 1. Some energy estimation equation
for feed evaluation using chemical components of feed
|
1
|
D.R.Martens
|
Legumes
|
|
||||||||
|
|
|
%TDNm=
|
86.2
|
-
|
(
|
0.513
|
x
|
NDF
|
)
|
|
|
|
|
|
NEL(Mcal/lb)=
|
1.054
|
-
|
(
|
0.0098
|
x
|
NDF
|
)
|
|
|
|
|
|
%TDNm=
|
84.2
|
-
|
(
|
0.598
|
x
|
ADF
|
)
|
|
|
|
|
|
NEL(Mcal/lb)=
|
1.011
|
-
|
(
|
0.0113
|
x
|
ADF
|
)
|
|
|
|
|
|
Grasses
|
|
||||||||
|
|
|
%TDNm=
|
105.2
|
-
|
(
|
0.667
|
x
|
NDF
|
)
|
|
|
|
|
|
NEL(Mcal/lb)=
|
1.297
|
-
|
(
|
0.119
|
x
|
NDF
|
)
|
|
|
|
|
|
%TDNm=
|
97.6
|
-
|
(
|
0.974
|
x
|
ADF
|
)
|
|
|
|
|
|
NEL(Mcal/lb)=
|
1.12
|
-
|
(
|
0.0159
|
x
|
ADF
|
)
|
|
|
|
2
|
Moran, Jhon 2005
|
TDN(%)=5.31 + 0.412
CP% + 0.249 CF% + 1.444 EE% + 0.937 NFE%
TDN (%)= 5.4 ME + 10.2
ME (Mcal.kg DM) = 0.185 TDN – 1.89
|
|||||||||
|
3
|
Alderman, 1985
|
ME (MJ/kg DM) = 11.78 + 0.00654CP
+ (0.000665EE) 2 – CF(0.00414EE) – 0.0118A
(UI eq. 25. Page 29)
Variables are in %DM
|
|||||||||
|
4.
|
TSE(9610)
|
ME (Kcal/kg OM) = 3260+0.455CP +
3.517EE - 4.037CF
Variables are in g/Kg OM
|
|||||||||
|
5.
|
MAFF (84)
|
ME (Mcal/kg DM) = 3227 - 35.85%ADF + 33.46%EE - 35.85%Ash
|
|||||||||
Energy
estimation (eq. (25 UI)) resulted from Alderman (1985) was selected for
legislation for estimate ME values. Equation (25) (UI) has a square term for EE, which
improves the fit with high energy (high fat) feeds. This agrees with what is
known about the metabolism of fat, but implies non-linearity of the ME of fat
when added to diets. Other energy estimation using chemical such as MAFF
(1984), TSE(9621) and Moran J (2005) using different chemical compound of feed.
Energy estimation approached by NRC (2001) equation was
mostly used for feed evaluation. The dietary energy requirements in NRC (2001)
consider feedstuff digestion dynamics as well as the energy requirements for
maintenance, growth, lactation, reproductive status and activity of the animal
(linn, J. 2003). The approach used in the NRC (2001) is to calculate the enrgy
value of feeds and diest directly from their nutrient composition. the chemical
component requirements and in vitro assay :
-
dNDF48 : Ash, fat,
crude protein, ADICP, NDF, 48h NDF, PAF
-
Lignin : Ash, fat,
crude protein, ADICP, NDF, lignin, PAF.
The NRC-2001 energy
equation system was evaluated by VandeHaar (2002) which was reported by Linn J
(2003) that found some legitimate concerns with the energy system when it is
applied to formulation of diets. These were :
-
Energy value of protein
feed may be over evaluated. The effect of the over is the energy concentration
in diets can be increased by feeding
higher protein diets.
-
The NDF digestibility
equation does not consider feed type. Variable effect of feed type due to
affect of lignin contain and in vitro digestibility of NDF after 48 hour does
not substitute directly for the calculated NDF digestibility value (Wisconsin
research), and the in vitro dNDF48 h was founded had higher value than in sacco
NDF digestion (Robinson, P.H. et al., 1999)
-
For high energy feed or
diet, the digestibility discount may be too aggressive. Fiber length of feed or
particle size is not accounted for in the model ad this will impact DMI.
The
NRC-2001 equation can be found on page 13 to 17 of nutrient requirements of
dairy cattle in NRC (2001).
|
tdCPf
(%) = [(CP*exp(-0.012*ADICP/CP))]
tdCPc
(% ) = [(1- (0.04*ADICP/CP)]*CP
tdNFC(%)
= 0.98*(100-[(NDF – NDICP) + CP + EE + Ash])*PAF
tdFA
(%) = FA, note : if EE < 0 à Fa = 0, if EE>1 à FA = EE – 1
tdNDF
(%) = [0.75 * ((NDF-NDICP) – Lignin)* (1-(lignin/(NDF-NDICP))0.667
or = tdNDF 48 hour or =
tdNDF30 h * 1.16
DE1x
(MCal/kg DM) = (tdNDF/100)*4.2 + (tdNDF/100)*4.2 + (tdCP/100)*5.6 +
(FA/100)*9.4 – 0.3
TDN1x
(%) = DE/0.04409
If
TDN = < 60%, the discount for diets was set to 1.0 (no discount)
If
TDN > 60%, DE1x should be corrected with discount for
productive level DEp
Discount
= [(TDN1x – [(0.18*TDN1x0-10.3)] * intake)]/TDN1x
Intake = 2, (3 -1) for cow 3x
maintanenace for above maintenance
DEp
(MCal/kg) = DE1x*Discount
MEp
(Mcal/Kg) = [1.01*(DEp) – 0.45] + 0.0046*(EE-3) , if EE > 3
MEp(Mcal/Kg)
= 1.01*DEp – 0.45, if EE < 3
NELp
(Mcal/kg) = [0.703**MEp)] – 0.19
NEm
(Mcal/kg) = 1.37ME – 0.138 ME2 + 0.0105ME3 – 1.12
NEg
(Mcal/kg) = 1.42ME – 0.174 ME2 + 0.0122ME3 – 1.65
NRC (20010)
|
UCD Energy Estimation
UCD energy estimation was tried to
correction the weakness of NRC (2001) energy system with different time NDF
digestibility (dNDF 30 h) and considered the protein soluble contain of feeds.
UCD energy estimation used chemical component of feed and in vitro gas
production test. The chemical components requirements were :
-
dNDF30 : Ash, fat,
crude protein, soluble CP, ADICP, NDF and 30 h NDF
-
Gas : 24 h gas
production in vitro.
The
estimation from 24 hour gas production was a modification of the method of
Menke and Steingass (1988) as well as estimates of the feed’s level of CP and
Fat.
|
TDN1x (%) =
((CP-ADICP)*(FT/5)*0.98)+((CP–ADICP)*(1-(FT/5))*0.80)
+ ((EE-1)*0.98*2.25) + (NDF*dNDF) + (0.98*(100-ASH-EE-NDF-CP)))
DE1x (Mcal/Kg) = (0.04409 x TDN1x)
ME1x
(Mcal/Kg) = ((DE1x)*1.01) – 0.45
NEL
1x (MCal/Kg) = (TDN1x*0.0266)
– 0.12
Discount
= ((0.033
+ (0.132*NDF(%DM))) – (0.033*NEL1x,Mcal/Kg)))
+ (NSC(%DM)*0.05)
NEL3x (MCal/KgDM) = NEL1x – ((NEL1x)*Discount
energy/100)*intake))
Intake = 2 , from (3x maintenance – 1)
NEm(MCal/KgDM)=
((1.37*(DE1x*0.82))- ((0.138*(DE1x*0.82)^2))
+ ((0.0105*(DE1x)*0.82)^3)) –
1.12
NEG(MCal/KgDM)=
((1.42*(DE1x)*0.82))- ((0.174*(DE1x)*0.82)^2))
+ ((0.0122*(DE1x*0.82)^3)) –
1.65
Where
: CP = crude protein (% of DM)
ADICP = acid detergent insoluble CP (% of DM)
FT = feed type (1=silage,2 =wet
by-product, 3 = others)
EE = ether extract (% of DM)
NDF = ash-free NDF
assayed with sodium sulphite and
amylase (% of DM)
dNDF = in vitro NDF digestibility at 30 hours
(% of NDF)
Ash = ash (% DM)
NE1 = energy value at 1xM
intake
NSC = non-fibre
carbohydrate calculated as 100-ASH-EE-NDF-CP
DE1x=
Digestible energy at maintenance level
NEL1x =
Net energy lactation at maintenance level
NEL3x = Net
energy lactation at production level
NEm = Net energy
maintenance at production level
NEG = Net energy gain at production level
Robinson P.H.
(2001)
|
TDN1x is the TDN value of a feed or diet at maintenance intake (NRC, 2001). Because NEL1x at maintenance is not representative of the energy value of feed or diet at production level, a discount factor was developed to correct for decrease net energy level at production (NEl, 3x). In UCD factorial approach to estimate feed energy levels. A discount energy factor was formulated based on NDF and NSC content of feedstuff and NEl(1xM) values as % per unit of energy intake (M).
Net energy values for lactation at level production
(NEl 3xM). The
energy content of a feedstuff is not
constant value. As its intake by the animal increase, its energy content tends
to decline, since it passes through the intestine faster allowing rumen
microorganism and intestinal enzymes less time to digest available nutrient. To
extent of the change, refer to as the energy discount or simply discount,
quantity the extent of this change. The discount is a reflection of the NDF and
NSC content of the feedstuff, and it can be calculated as % per unit of energy
intake .
|
ME
(MJ/kg DM) = 1.25 + (0.0292*gas24) +(2.46*fat) + (0.0143 c (CP-ADICP))
Where : gas24 is gas production in 24 hour
(ml/g DM) and others variable are in g/kg DM
|
The UCD equation evaluation result in low value of precision of prediction value (r2) for UCD gas (0.50) , while it had higher value for UCD30 (0.83) than NRC48 or NRClig.
Energy Equation in TMR (Boguhn J. et. al 2003)
Total mixed ration, complete diet for ruminant was less
predicted by equation and have so far not beed developed, and TMR can only be
evaluated if the composition and the energy value of the ingredients ae known. Boguhn J. et al. (2003) reported prediction of
ME in TMR using chemical feed data, gas production and enzymatically degraded
organic matter (EDOM).
|
ME (MJ/kg DM) =
6.0756 + 0.19123EE + 0.02459CP – 0.000038CF.CF - 0.002139 EE.EE – 0.000060 CP.CP ( r = 0.83)
|
|
ME (MJ/kg DM) = 8.9695
+ 0.04095GP - 0.01267CF + 0.04108EE
+ 0.00387CP + 0.00508Ash ( r =
0.83)
|
|
ME (MJ/kg DM) = 13.903
– 0.0147 Ash – 0.01114 EUDOM + 0.00234CP (r = 0.82)
|
Where : GP = gas production in ml/200 mg DM, others variable in g/kg DM EUDOM = enzumatic undegraded organic matter
The
equation was determined from 30 TMR which was analyzed for nutrients, gas
production and enzymatic degraded or undegraded organic matter. The equation
no.3 and 8 from table 4 pages 263 was recommended (Boguhn J. et al., 2003).
RESUME
Estimation
energy value of feed by some equation raised overestimated or underestimated
value from truly energy value. It should be considered four using selected
equation depend on available data. Using chemical component analyze only was
considered for some type of feed which clearly information known. Best estimation
of energy value of feed is using combination between chemical component of feed
and digestibility data (in vitro or in vivo). NRC-2001 system for energy
estimation which was commonly used and recorded in NRC table still not enough
precision for some feed. However the UCD30 was resulted in some correction for
it.
The
authors thanks Professor Murat Gorgulu and Professor Hasan Rustu Kutlu for
literature sources and attention.
REFFERENCES
Alderman, G. 1985. Prediction of the energy value of compound feeds : In Haresign W and D.J.A Cole. Recent Advances in Animal Nutrition – 1985 . Univ of Nottingham. UK.
Boguhn J., H. Kluth, O. Stenhofel, M. Peterhansel and M. Rodehutscord. 2003. Nutrient digestibility and prediction metabolizable energy in total mixed ration for ruminants. Arch. Anim. Nutr., 57(4) : 253-266.
Moran, J. 2005. Tropical dairy farming : feeding management for small holder dairy farmer in the humid tropics. Landlink press. P.312
