Energy C o n s u m p t i o n on a D a i r y Farm as a
F u n c t i o n of T e c h n o l o g y and Size'
G. C. MISENER and L. P. McMILLAN
Fredericton, New Brunswick
ABSTRACT valid only for the proces and costs in the
The cost of milk production in terms analysis. Resources considered were land, labor,
of energy consumption is estimated by an electricity, fossil energy, capital, and dollar.
input-output computerized model. The The study included only the milking herd and
trade-offs in the mass energy and mone- related housing and machinery.
tary costs associated with various capac-
DAIRY FARM MODEL
ities were determined. Economies of size
to all production variables were found A mass-energy model was developed by
with the exception of fossil fuel. The Misener (4) which can be utilized to estimate
increase in average fossil fuel over output the energy requirements for a dairy farm. The
size results from the increased use of fuel milk production process is viewed as a collec-
for transportation. Analysis of the effect tion of components which interact with each
of free stall barn type, waste storage type, other and their environment via mass and
and forage storage type indicated that energy exchanges. Essentially three basic func-
average costs were lowest, in terms of the tions are performed by the components: mater-
economic and energy variables, with an ial transformation, material transportation, and
open lot and solid waste system and material storage. These basic functions are
highest with the warm-enclosed free stall performed at a cost to society in terms of
barn and liquid waste systems. human energy, solar energy, and physical
energy (3, 7). These energy costs as well as the
OBJECTIVES flow of material into and out of the systems
and between the components of the system are
The study was undertaken to assess energy
computed by the input-output model. The
consumption and to identify mass-energy
functional structure of the milk production
trade-offs as functions of technology and size
system is in Fig. 1. Shelled corn, corn silage,
of a dairy farm. The energy or cost associated
and haylage are produced for feed (components
with milk production represents the cost of
1, 2, and 3). Each is transported to storage
nonrenewable resources used to alter the spatial
(components 2T, 3T, and 4T). The shelled
location and physical or other forms of the
corn, silage, and haylage are combined into a
renewable resources to place the final product
ration (component 4) which is fed to the
into its current form and location. Energy can
milking herd (component 5). Waste material is
be measured in several dimensions such as solar
decomposed into recyclable nutrients (nitrogen,
energy, human energy, and physical energy as
phosphorus, and potassium) as well as non-
suggested by Koening and Tummula (3). Alter-
nutrient portions. Losses of waste and nutrients
natively, an economic measure can be utilized
are four leakage flows (components 6, 7, 8, and
to map the several dimensions into one unit,
9). The waste and nutrients are transported to
dollars per unit of material. The analysis then is
the cropland by a common carrier transport
component (component 1T) since in reality all
four materials are handled simultaneously. The
Received June 4, 1975.
1This research was conducted at Michigan State nutrient flows are combined with equivalent
University through the cooperation of the Depart- commercial fertilizer so that the total amount
ments of Agricultural Engineering, Agricultural Eco- of each material is adequate for crop needs (5,
nomics, and Electrical Engineering and Systems Sci- 6). Each material flow in Fig. 1 ultimately
ence. The research was financed partially by a grant
from NSF/RANN and was part of a project titled depends on the amount of milk produced by
"Ecosystem Design and Management." the system. Milk is defined as the stimulus
D A I R Y FARM E N E R G Y CONSUMPTION 533
and capacity as well as crop yields. The model
selects a machinery complement, including
power units, which is capable of performing all
field operations at a rate sufficient to achieve a
successful crop. The model begins by estimating
horsepower needed for the cropping operations.
Then the tractors and field machines are select-
ed, and the processing energies are calculated.
Transportation is the link between the field
crop production model and the farmstead
model. The transportation model determines
the number of each kind of transportation
equipment needed and evaluates the processing
DAIRY FARM SYSTEMS DESIGN energies required for transportation. For tech-
FIG. 1. Material flows in a milk production system. nologies in this study, the transportation sys-
tem consists of three components: liquid and
solid waste transport, haylage and corn silage
variable. transport, and high moisture corn transport.
The model expresses all input and output
material flows for a given system and the cost
APPLICATION OF MODEL
associated with the production of milk as
functions of technology and capacity of the The trade-offs ill the mass-energy and mone-
production unit. Technology is denoted by tary costs associated with various production
technical coefficients which are included in the systems were evaluated. Three crops were con-
material flow and energy equations (4). Thus, sidered in the analysis: high moisture corn, corn
one can evaluate the trade-offs in the mass- silage, and haylage. A cropping schedule (Table
energy and economic characteristics that might 1) was developed for soil and climatic condi-
be realized from various technology-size spe- tions available in Southern Michigan. The start-
cific structures in milk production. Many of the ing and finishing dates (input data) of the
technical coefficients which are utilized in the cropping sequence are representative of this
input-output model are not available in the area. The remaining information in Table 1 is
literature. Consequently, additional modeling computed by the program.
supplied adequate values for the coefficients. To determine the effect that ration and herd
Three subsystem models were developed which size have on energy consumption, two rations
describe the farmstead, cropping, and transpor- with varying sizes of the production unit were
tation. considered in the analysis. Both low and high
The farmstead subsystem model includes corn silage rations (1) were used in the study
housing, milking parlor, feed storage, and other (Table 2). The sizes of the various components
components concerned with confining, milking, were matched to desired output. We evaluated
and caring for the milking herd. The model the effect o f free stall barn type, waste storage
specifies the size of each structure, type of type, and forage storage type listed in Table 3
milking parlor, and required farmstead equip- on energy consumption. The size of the produc-
ment. From soil and weather characteristics of tion unit was held constant during this portion
a location, the acreage required for each crop of the study.
and the total size of the farm are determined
for a particular technology and capacity. Opera-
R ESU LTS
tional costs of the farmstead are expressed in
terms of the six resources which were defined. A machinery system selected by the program
The field machinery subsystem model selects for a 150-cow farm operation utilizing a low
a set of tractors and field machines required for corn silage ration is shown in "Fable 4. Annual
the field operations for producing and har- machine costs are given also. Similar o u t p u t can
vesting the crops. The set of field operations be obtained for the farmstead and transport
and the land area depend on the technology sections.
Journal of Dairy Science Vol. 59, No. 3
534 MISENER AND McMILLAN
TABLE 1. Cropping schedule and machinery energy requirements in analysis.
Starting Finishing requirements
Set date date Operation (watts) Hectares
1 4/17 5/25 Plow 5.51 × 104 64.7
Disc 5.51 X 10 4 86.3
Harrow 5.51 × 104 86.3
Plant corn 5.51 X 104 86.3
2 5/26 5/27 Plow 3.61 X 104 8.3
3 5/28 6/17 Cut and windrow 2.02 × 104 41.7
Chop forage 2.02 × 104 41.7
4 6/28 6/30 Cultivate corn 1.10 × 104 86.3
Fertilize alfalfa 1.10 × 104 41.7
5 7/5 7/26 Cut and windrow 1.16 × 104 41.7
Chop forage 1.16 × 104 41.7
6 7/27 8/3 Disc 4.85 × 103 8.3
Harrow 4.85 × 103 8.3
Plant alfalfa 4.85 X 103 8.3
7 8/16 9/5 Cut and windrow 1.30 × 104 41.7
Chop forage 1.30 × 104 41.7
8 9/6 9/24 Chop corn silage 2.70 X 10 a 16.3
9 9/26 10/24 Combine 3.72 × 104 70.0
10 10/25 12/14 Chop stalks 5.18 X 104 70.0
Plow 5.18 X 104 21.6
TABLE 2. Average daily rations a for a 635-kg cow producing 6000 kg of milk annually.
High moisture corn b Corn silage b Haylage b
Ration kg/day per cow kg/day per cow kg/day per cow
High corn silage ration 7.48 24.54 3.27
Low corn silage ration 10.2 9.66 13.42
aAdditional supplement was added to both rations according to Black et al. (1).
bMoisture contents are: corn (~ 30%, corn silage (a~ 65%, and haylagc (a~ 50%.
TABLE 3. Energy consumption for various technologies (150 milk cows).
Capital Labor Fuel Electricity Cost
Free stall Waste Forage $/kg h/kg liters/kg J/kg $/kg
barn system silos (X 10-1 ) (X 10-3 ) (X 10-~) (X 10 s) (X 10 - l )
Open lot Solid Bunker 6.82 10.80 1.59 4.54 1.49
Open lot Solid Tower 7.02 9.26 1.59 4.79 1.51
Cold covered Solid Bunker 6.92 9.92 1.59 4.75 1.51
Cold covered Solid Tower 7.07 9.48 1.63 4.97 1.52
Cold covered Liquid Bunker 7.07 9.92 1.67 4.75 1.52
Cold covered Liquid Tower 7.21 9.26 1.67 4.97 1.53
Warm enclosed Liquid Bunker 7.17 9.92 1.67 5.15 1.54
Warm enclosed Liquid Tower 7.31 9.26 1.67 5.36 1.55
Journal of Dairy Science Vol. 59, No. 3
DAIRY FARM ENERGY CONSUMPTION 535
TABLE 4, Machinery system a selected for 150-cow farm operation.
width machine cost b
Machine M $/yr
Plow 2.01 253.12
Disc 5.79 327.78
Harrow 9.14 224.79
Planter 9.14 381.52
S. P. windrower 3.05 1375.87
Forage harvester 1.52 635,20
Cultivator 6.10 257.86
Fertilizer applicator 350.03
Grain drill 4:88 357.47
Stalk chopper 3.35 196.98
S. P. combine 2.29 2122.68
Tractor 7.38 X 104 (watts) 1795.13
aAdditional machinery is required for transportation.
bBased on 1974 prices.
The results in Fig. 2 to 6 depict systems fossil fuel. Most of these economies are attained
utilizing a cold covered, free stall barn, herring- at capacities at the upper limit of the study.
bone milking parlor, liquid waste system, and The irregularities in the labor curves (Fig. 2)
tower silos with mechanical feeders. Figures 2 occur because of changes in the field m a c h i n e r y
to 6 provide a comparison of energy consump- systems. The shape of the labor r e q u i r e m e n t
tion b e t w e e n a low and high silage ration with curves results f r o m the use of labor by various
various capacities. Essentially little difference in parts of the system (Fig. 7). For systems with
energy c o n s u m p t i o n can be n o t e d b e t w e e n the low capacity, time for field crop p r o d u c t i o n is
systems utilizing either ration e x c e p t m o r e land high because field machines were selected
is required for the system using the low corn
silage ration. There are e c o n o m i e s of size to all
variables of p r o d u c t i o n with the e x c e p t i o n of
.J Low Corn Silage
=~ 10 _ _ High Corn Silage
Low corn silage
,,s _ _ High corn silage I--
'~_ 16" S
I.- c,~ 12" ,.-,, x 6
160 260 36o 460 ~60 10b 260 360 460 560
NUMBER OF M I L K I N G COWS NUMBER OF M I L K I N G COWS
FIG. 2. Labor use as influenced by herd size and FIG. 3. Capital requirement as influenced by herd
ration. size and ration.
Journal of Dairy Science Vol. 59, No. 3
536 MISENER AND McMILLAN
L o w corn silage
L o w Corn Silage It _ _ High c o r n silage
.d High Corn Silage 0
I-- re r~ f
.d 100 200 300 400 500
16o ~o 3bo 4~o 560 NUMBER OF MILKING COWS
FIG. 6. C o n s u m p t i o n o f fossil fuel as i n f l u e n c e d b y
NUMBER OF MILKING COWS
h e r d size a n d ration.
FIG. 4. A n n u a l c o s t o f m i l k p r o d u c t i o n as in-
f l u e n c e d b y h e r d size a n d r a t i o n .
necessary to start production with a given
technology. Small farms utilize small equip-
ment and small feed storages which tend to
which tended to spread machine use over the have higher initial cost per unit of milk pro-
allowable working time. At the upper end of duced than larger production systems. In addi-
the capacity range, transport labor per unit of tion, with systems having low production, some
milk increases which counteracts the decrease machines which are required to conform to the
in field labor. Administration time was assumed specified technology are not used to capacity
to be 1000 h per yr for all systems. although the smallest available units are used.
Capital includes all the initial investments
for land, machinery, buildings, and animals
.d ..... Farmstead
it ..J ..... Transport
t-- L o w C o r n Silage
10 High C o r n Silage 16-
O. X 12"
re X 8-
Z _ .......
160 200 36o 460 560
NUMBER OF MILKING COWS
O 100 2bo 3~0 ,~0 5rio
FIG. 7. B r e a k d o w n of l a b o r r e q u i r e d b y the
FIG. 5. C o n s u m p t i o n o f e l e c t r i c i t y as i n f l u e n c e d various s e g m e n t s o f the s y s t e m u t i l i z i n g a l o w corn
b y h e r d size a n d ration. silage r a t i o n .
J o u r n a l o f Dairy S c i e n c e Vol. 59, No. 3
DAIRY FARM ENERGY CONSUMPTION 5 37
v _ _ Total trucks for transporting silage or other waste
...... Farmstead handling methods was not explored. Also,
_ _ Cropping
smaller farmers using other technology may
F- realize savings not indicated by the technologies
used in this study. However, given the appro-
f priate data, such analyses can be made.
O The energy consumptions for systems using
g × various technologies are shown in Table 3 for a
milking herd of 150 cows. A low corn silage
ration was used. Average costs are highest, in
o terms of economic and energy variables, with
the warm enclosed free stall barn and lowest for
,,= the open lot. Systems utilizing a liquid waste
m handling method required more capital and
03 S Z : ~. . . . . .
thus higher dollar cost for milk production than
2 160 2d0 s60 460 ~60 systems using a solid waste handling method.
Land and electrical energy requirements are
N U M B E R OF M I L K I N G COWS
essentially independent of the waste handling
method. When bunker silos are used with this
FIG. 8. Breakdown of fossil fuel consumption by herd size rather than tower silos in otherwise
the various segments of the system utilizing a low corn
silage ration. equivalent systems, the energy costs per unit of
milk produced are lower except for land and
The net effect of these two considerations is a Additional work needs to be done to ac-
higher capital requirement per unit of milk count for the dry cows and young stock. These
produced for systems with low production. additional animals would increase significantly
The amount of fossil fuel required per crop the energy consumption; however, the same
hectare is virtually independent of the size of trend of results would be expected.
the machinery employed. The increases in
average fossil fuel use over output size result CONCLUSIONS
from the increased use of fuel for transporta-
tion (Fig. 8). As the capacity of the production The effect of technology and capacity of the
unit increases, fuel costs are driven up by the production unit has been analyzed by a mass-
additional a m o u n t of wastes and feed which energy economic model. Resource costs (land,
must be transported over longer distances. labor, and physical energy) in addition to dollar
cost associated with milk production on a single
The shape of the dollar cost curves reflects
enterprise farm have been presented. It is
the shapes of the other energy cost curves. The
essential that we consider the relationship
dollar costs per unit of milk are slightly higher
between the rrmss-energy and the economic
for the system using the low corn silage ration
characteristics of the production process. Once
than the system using the high corn silage
the mass energy flows are known, the monetary
costs can be determined at any point in time.
The results follow the trend found by Kizer
In general, there are economies of size to all
and Partenheimer (2) by their optimum farm
variables of production with the exception of
systems simulation model. They found econo-
fossil fuel. Average costs were lowest, in terms
mies of size between 100 and 600 cow herds.
of the economic and energy variables, with the
They attributed these diseconomies to the
open lot and solid waste system and highest
lumpiness of capital input as herd size in-
with the warm-enclosed free stall barn and
creased, and to higher labor requirements per
liquid waste system.
cow due to longer travel distances to dispose of
The same technology was used for all sizes REFERENCES
of the production unit. Hence, increased pro- Black, J. R., P. Wonderschnieder, and S. Nott.
ductivity from options such as using large 1974. Alfalfa and corn silage combinations to
Journal of Dairy Science Vol. 59, No. 3
538 MISENER AND McMILLAN
maximize Michigan dairy farm income. Agricul- model of a dairy farm. Paper prepared for the
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farms. Agricultural Experiment Station, Pennsyl- 431.
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netics, SMC-2(4) :449. energy based economic models. IEEE Transactions
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Journal o f Dairy Science Vol. 59, No. 3