HOUSING PIH-11
PURDUE UNIVERSITY. COOPERATIVE EXTENSION SERVICE.
WEST LAFAYETTE, INDIANA
Swine Growing-Finishing Units
Authors
Vernon M. Meyer, Iowa State University
L. Bynum Driggers, North Carolina State University
Kenneth and Debra Ernest, Sidney, Ohio
Reviewers
Larry D. Jacobson, University of Minnesota
George F. Grandle, University of Tennessee
William B. Thomas, Texas A & M University
J. Kevin and Audrey Rohrer, Manheim, Pennsylvania
The term ``growing-finishing'' pigs describes that range in
weight from as low as 40 lb. to market weight. The age range is
from about 8 wk. to 23 to 28 wk.
The age range is usually split into two groups. When this is
done, pigs spend about 8 to 10 wk. in a growing unit and the last
8 to 10 wk. in a finishing unit. Each group is kept in a separate
room or facility. Splitting them into groups is consistent with a
trend toward ``all-in/all-out'' management of growing-finishing
units.
Pigs moved to the grower unit in winter at 40 lb. need a
minimum temperature of about 70o F. A grower unit needs better
environmental control than the finishing unit in cold weather
with supplemental heat required in cold climates.
Desired Environment
The desired temperatures for growing-finishing pigs are
similar to what is shown in Table 1.
Temperatures
Pigs have the ability to adjust to temperatures outside the
range shown, but they are most productive within the range. In
extremely cold weather it is better to let the temperature drop
slightly and keep the humidity down than it is to cut back on
ventilation.
When using the all-in/all-out principle, the ventilation
opening thermostat can be changed once a week to match the age
and weight of the younger pigs. Today's controllers permit more
exact control than was possible previously.
The use of bedding allows temperatures to drop from 5o to 8o
F below the above low values in Table 1 and still keep the pigs
comfortable.
Table 1. Suggested temperature range for growing-finishing pigs.
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Approximate
Age, wk. Pig weight, lb. suggested temperature range,o F
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9 46 73-82
10 56 70-82
11 68 68-80
12 80 66-80
13 92 64-80
14 104 62-80
15 116 60-78
16 128 58-78
17 141 56-78
18 155 56-75
19 171 54-75
20 187 52-75
22-mkt. 215 & up 50-75
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Relative Humidity
Try to maintain the relative humidity between 50% and 60% to
minimize the growth of disease microorganisms. Some disease
microorganisms grow rapidly at humidities above 60% while others
grow well at low humidities. When ventilation is sufficient to
keep the humidity below 60%, other contaminants, such as gases
and respirable dust, tend to be low as well.
High relative humidities promote rapid corrosion of metal
equipment, creating an additional expense. High relative humidi-
ties also lead to more rapid deterioration of the electrical sys-
tem, contribute to condensation problems, and accelerate destruc-
tion of wood and truss plates when trusses are exposed.
Gas Levels
Suggested allowable concentrations of the three common gases
found in swine buildings are as listed in Table 2. These concen-
trations are easily achieved with an adequate ventilation system.
At higher concentrations, each of these gases can be detrimental
to animal and human health and to productivity.
Table 2. Suggested maximum gas levels in swine buildings.
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Gas ppm
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Ammonia 10
Carbon dioxide 3000
Hydrogen sulfide 5
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Dust
Dust is an irritant that can increase respiratory problems
in both swine and humans. Several options are available to help
control dust.
Dust that settles on equipment and building components
should be periodically washed down to keep it from being picked
up and returned to the air. Adding fats or oils to the feed can
remove more than half of the total room dust. Equipment to
remove dust from the air is being studied and may be available in
the future. In the meantime, persons who spend extended periods
in enclosed facilities would be wise to wear dust masks.
Building Types
A variety of buildings are used for both growing and finish-
ing pigs. The buildings used can be classified as one of four
general types:
1. Open front shed, outside concrete.
2. Enclosed building, naturally ventilated year-round.
3. Enclosed building, fan ventilated in winter-naturally
ventilated the rest of the year.
4. Enclosed building, fan ventilated year round.
Open Front with Outside Feed Floor (Fig. 1 & 2)
Bedding is recommended during winter in cold climates. Slope
inside the floor 1/4 in. per ft. if bedding is used. Consider
having enough building height to use a skid loader or small trac-
tor for cleaning.
Collect runoff at the lower end of the outside floor as
required to meet state and federal pollution requirements. Pro-
vide a curb or collection alley to contain the manure.
Locate the waterer near the mid-point or lower part of the
outside floor. Locate the feeder near the shed, unless it must
be filled from the lower end of the pen. Additional shade may be
needed in hot weather.
box height 1.8i width 3.25i "% Figure 1. Open front outside apron
building with gable style root." box height 1.5i width 3.25i "%
Figure 2. Open front outside apron building with single slope
roof."
Enclosed Buildings
The trend has been toward the use of naturally ventilated
buildings for larger hogs. Temperature-actuated door and curtain
controllers make it possible to achieve an environment similar to
that possible with fans. The most difficult times to control the
environment are during extreme cold in winter and extreme heat in
summer and during rapidly changing weather in fall and spring.
Some producers, therefore, use exhaust fans to provide a more
uniform temperature in cold weather and use mechanical or natural
ventilation for the rest of the year. In hot weather, circulating
fans and sprinklers can provide comfort.
Building Construction
Building Width
Inside an enclosed building with a single row of pens, the
building width is generally from 24 to 30 ft. (Fig. 3, 4, 5, and
6). With two rows of pens, the width will range from 40 to 48 ft.
(Fig. 7, 8, 9, 10, and 11).
Pen Layout
A common concern with having a partially slotted floor and
open gutter flush floor buildings is the dunging habits of the
pigs. The slotted or gutter portion is intended to be the dunging
and waste collection area and the solid floor the resting area.
Both ventilation air patterns and pen layout can influence how
clean the pigs keep the solid floor resting area.
The following are suggestions for pen design and management
to help train pigs in partially slotted pens, or pens with open
flush gutters.
1. Use a solid partition over the solid floor resting
area, and along the alley adjacent to resting area.
2. Provide a vertical or horizontal bar, open gate over
the slotted floor or flush gutter area.
3. Place waterers near, or over, the slotted or flush
area.
4. Provide a 2 to 3 in. step-down from the solid to the
slotted area or a 4 to 6 in. step-down to the gutter
flush area.
5. Wet the slotted floor immediately before moving pigs
into the pen and sprinkle feed on the resting area.
6. Adjust ventilation air movement as needed to make the
resting area the most comfortable area for the pigs
throughout the year.
7. For small pigs, use a hover over the resting area in
cold weather.
8. Locate feeders on the solid floor area close to the
slotted area. This allows the use of a crowd gate to
keep the resting area matched to the size and number of
pigs in the pen.
9. Flush often (once each 30 to 40 minutes) in open gutter
flush systems.
All of the above will have no influence when the most com-
fortable part of the pen is the waste collection area, because
that is where the pigs will rest; and they will dung on the solid
part of the floor. In cold weather, the resting area must be kept
draft-free with the colder ventilation air brought in over the
dunging area. In summer the resting area should have good air
movement. It may take intermittent sprinklers in the dunging
area with paddle fans in the resting area to encourage proper
resting and dunging habits during summer months. The dunging area
must be the most uncomfortable area for the pigs at all times.
Pen dimensions are not as critical with totally slotted
floors, and the feeder and waterer locations are also of less
concern.
Insulation
Use the indicated insulation values for your climate, (Fig.
12 and Table 3).
Table 3. Suggested R-values for enclosed buildings.
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Climate Suggested R-value
Wall Ceiling
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Cold 14-20 25-35
Moderate 14 14-20
Mild 5 5
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Always use perimeter insulation 18 to 24 in. below ground
level for moderate and cold climates. Rodent proof barriers are
required on all insulation less than 24 in. below grade. Earth
sheltering complements, but does not replace, insulation.
The building must be adequately insulated to prevent conden-
sation on surfaces and to allow enough ventilation to keep the
humidity in the desired range in winter. With adequate insula-
tion, no extra heat is required to maintain the temperature
except during severely cold days or when housing very young pigs.
Repair or replace insulation damaged by rodents.
For more detailed information, see PIH-65, Insulation for
Swine Housing.
Alley Width
A 30-in. wide alley is usually sufficient. An alley too wide
will permit pigs to turn around when being moved. A wider feeding
alley may be needed if a feed cart is used.
Table 4. Suggested minimum space per pig.
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Pig weight, Enclosed Shed with outside lot
lb. building Inside Outside
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---------Sq. ft./head--------
40-100 4-5 5 8 - 10
100-160 6-7 6 10 - 12
160-220 8-9 8 12 - 15
over 220 10 9 14 - 16
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Waterers
Make sure pigs have access to water (Table 5). Lack of suf-
ficient water can reduce efficiency and rate of gain. Inadequate
waterer space, restricted flow, or partially plugged waterers are
the most common reasons for a lack of sufficient water. Locate
waterers in the area of desired dunging.
Provide sufficient waterers and check the flow rate of nip-
ple waterers at least once a month. Use a cup and stop watch to
determine flow rate.
Table 5. Water requirements.
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Pig Weight
Item 40-125 lb. 125-230 lb.
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Pigs per nipple or cup 12-15 12-15
Nipple height, in. 15-24 24-30
Flow rate, quarts per minute 0.5 0.7
Daily water consumption, qt. 6-10 8-12
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Water consumption varies with air temperature. Higher rates
are needed in hot weather.
Keep nipple waterers at least 12 in. apart. Set nipple
waterers at a 15 degree angle downward unless otherwise indicated
by the manufacturer. Position nipples at a height between the
middle and top of the pigs' front shoulders. Limit the pressure
going to the nipples to 30 psi. A pressure reducing valve is
desirable in most instances. Locate water lines away from incom-
ing air to prevent freezing.
Feeder Space
Any restriction of the pigs' ability to eat whenever hungry
can slow the rate of gain. Floor feeding can increase the time
to market from a week to 10 days. Floor feeding can be used suc-
cessfully, if knowledge of feed intake patterns is established
and management skills are adequate.
If space at a self-feeder is limited, the daily gain can be
slowed for at least some of the pigs. Provide one feeder space
for each four or five pigs. For example, a six-hole feeder can
feed a pen of 24 to 30 pigs, and an eight-hole feeder can feed a
pen of 32 to 40 pigs.
Pen Partitions
Avoid partitions or gates that permit pigs to climb the
fence with their front feet. A hog panel with rectangular open-
ings is an example of a partition that has caused foot injuries.
Solid pen panels are desirable on the solid portion of par-
tially slotted floors. Solid concrete, concrete filled block,
plastic planks, oak and similar durable wood can be used if
joints are installed flush so pigs cannot find a spot to start
chewing.
Vertical or horizontal bar gates or panels are suggested for
any open partitions such as over the slotted area or open flush
gutter.
Partitions should be 32 in. high in the growing area and at
least 36 in. high in the finishing area.
Inside Wall Linings
Any wall within the pens should be of a pig-proof material.
Walls along alleys should also be somewhat pig resistant, but
they are not subject to as much damage as pen walls.
Concrete, fiberglass reinforced plastic, recycled plastic,
and properly protected plywood are examples of suitable materi-
als. Use moisture resistant materials, so dust and cobwebs can be
cleared from walls and ceiling occasionally. See PIH-32, Build-
ing Materials and Equipment for Swine Facilities.
Manure Handling
Slotted floors (partial or total) are most common in
enclosed buildings. Some producers use a solid floor with a dung-
ing alley and scrape with a tractor or skid loader 2 or 3 times a
week (See Fig. 3). Scraping requires extra labor to close and
open gates (pigs are held in the upper part of the pen), and good
sanitation is hindered because the pigs are exposed to manure
longer. Another option is open gutter flushing. The building
design would be similar to that in Fig. 3.
Some hand scraping of the solid area should be anticipated.
Be sure the total manure management system complies with local,
state, and federal requirements. Increasing concerns about water
quality are putting added pressure on producers to manage all
manure and runoff in environmentally sound ways year-round.
Manure Handling, Slotted Floors
The floors in enclosed buildings may be partially or totally
slotted as shown in Fig. 4 and 7. A partly slotted floor should
be about 1/3 slotted with a minimum slotted width of 8 ft.
Space below the slotted floor may be:
1. Deep pit, usually 6 to 10 ft. deep.
2. Mechanical scraper, 10 in. to 24 in. deep.
3. Gravity drain (pull-the-plug), 18 in. to 24 in. deep.
4. Flushing system, 8 in. to 24 in. deep.
5. Pit recharge, 32 in. to 36 in. deep.
Deep Pit
1. May be less total investment as storage under a build-
ing costs less than a formed storage pit outdoors.
2. Odors and gases are more of a problem even with a good
pit ventilation system. Pit tubes or ducts are more
effective than pit wall fans.
3. Agitation of the pit prior to emptying can produce
dangerous concentrations of toxic gases. Operate venti-
lation system at maximum capacity when agitating or
emptying pits.
Mechanical Scraper
1. Requires some maintenance.
2. Can remove manure from the building daily or more
often.
3. Higher ammonia levels can occur in the building unless
water is added after each scraping. This volume of
water must be accounted for in sizing manure storage.
Gravity Drain
1. Sometimes called a ``pull-the-plug'' gutter.
2. Manure accumulates from 1 to 2 weeks before plug is
pulled.
3. Gutters with a Y, V or U shaped bottom drain well, but
a rectangular shape is easier to construct and the
trend is towards using it.
4. Plugs have been placed at both ends of the flat bottom
gutter to help in cleaning. A plug at one end is pulled
to drain the gutter, and at the next draining, the
opposite end plug is pulled. An adaptation of this is
the hairpin gutter (Fig. 13).
5. Hairpin gutters need less drain pipe to transport the
manure to storage than gutters with a drain on each
end.
Flushing Under Slats
1. Large amounts of water are required, so a lagoon must
be used.
2. Cleans manure from the building more completely than
other systems.
3. Salt can accumulate in pipes, screens and pumps, res-
tricting capacity, if water is recycled from a lagoon.
4. An irrigation system is normally required to distribute
the manure in the fields.
5. A gutter wider than 5 ft. should be divided into two
smaller channels for adequate cleaning.
Pit Recharge
1. Requires less pumping of water than flushing.
2. Less cost than flushing by eliminating all flushing
tanks.
3. Requires a lagoon for storage.
4. Advantages are similar to flushing.
Manure Handling, Open Gutter
An open dunging area in a pen may be cleaned by flushing or
by hand or mechanical scraping.
Open Gutter Flush
1. Building cost is less than for slotted floors.
2. Low in-house odors.
3. Pigs are attracted to running water and are easily
trained.
4. There is some cooling benefit during hot weather.
5. Pigs are exposed to any live disease microorganisms and
additives in recycled water.
Open Gutter Scrape
1. Similar to partially slotted floor with a scrape gutter
where slats would be located.
2. Need 5 to 6 in. step-down for gutter.
For further information on manure handling systems see:
PIH-95, Gravity Drain Gutter Systems; PIH-105, Scraper Systems
For Removing Manure From Swine Facilities; PIH-62, Lagoon Systems
For Swine Waste Treatment; and PIH-63, Flushing Systems For Swine
Building.
Ventilation
The ventilation system used must be designed so that the
dunging area is the most uncomfortable part of the pen and the
resting area is always the most comfortable, regardless of out-
door weather. In a partially slotted floor, the resting area
should permit no drafts during the winter and yet provide air
movement for cooling in the hot summer. In a totally slotted
floor pen there should be a comfortable area in the pen at all
times even though that location in the pen can change as the
weather changes.
Cold incoming air that is more likely to cause a draft
should be directed toward the dunging area.
Incoming summer air should provide air movement over the
resting area in hot weather. Problems occur with a sudden tem-
perature drop. If the cooler air drops in the resting area, the
pigs will change their dunging patterns to the dismay of the pro-
ducer.
Natural Ventilation
Natural ventilation (or non-mechanical ventilation) depends
on wind pressure (natural breezes) and thermal buoyancy (warm air
rises) to move air through the building. There must be inlets and
outlets as with any ventilation system.
To help control wind currents in a naturally ventilated
building, it is sometimes necessary to install solid partitions
across the width of the building. Install a divider for buildings
longer than 75 ft.
Provide openings on the windward side that can be opened in
summer but closed in winter. Openings on the downwind side should
be capable of meeting both winter and summer ventilation require-
ments. Provide openings on the end walls for improved hot weather
ventilation.
Doors or Curtains
The side openings in a naturally ventilated building should
be easy to control because of the rapidly changing temperature
and wind direction which occurs in much of the country. The trend
has been toward the use of curtains. A simple curtain works well
in mild climates (Fig. 14). An insulated curtain is being used in
cold climates (Fig. 15). In moderate climates an insulated cur-
tain may be used on the north side of the building with an unin-
sulated curtain on the south. Another option is to use insulated
doors on the north instead of an insulated curtain.
A folding curtain can be a haven for mice during the time
the curtain is folded for several months in warm weather. Run the
curtain up and down every week to combat the problem. Another
option is to use a sliding curtain. This requires that the solid
part of the wall be at least as high as the width of the curtain.
For example, a 4 ft. sliding curtain could be used on a wall that
is 8 ft. high. Keeping the bottom of a sliding curtain closed
tightly in cold weather is a concern because air enters at the
bottom of the curtain.
Insulated doors can pivot at about the center point or
slightly above it or be hinged to swing in or out (Fig. 16).
Pivot doors prohibit bird screens. A door that swings in may be
an obstacle to movement in the alley. If the rear doors require
manual control, an alley located along the rear wall provides
more convenient access to the doors than may be possible from
outside the building.
Cover openings with 3/4 in. to 1 in. plastic mesh screen to
keep birds out. The openings could frost over in very cold
weather. Tapping the screen gently will usually free the opening.
Ridge or Chimney
The best air outlet for winter exhaust in a naturally ven-
tilated gable roof building is through the ridge or a chimney
that exits at or above the ridge. Three types of construction
are being used. For milder or moderate climates, an open ridge
with insulation under the roof seems practical (Fig. 5 and 8). In
cold climates, a system that permits more insulation to be
applied easily is a consideration (Fig. 9 and 10). The continuous
center chimney building requires more labor to construct than a
building that is insulated only under the roof but it allows for
the use of loose-fill insulation over the flat or slightly sloped
part of the ceiling. The square chimneys, spaced at regular
intervals, (16 ft. to 20 ft.) allow the use of loose-fill insula-
tion over nearly all of the ceiling.
During cold weather, when thermal buoyancy controls the ven-
tilation, the exhaust area need not be very large. At high summer
temperatures, there is little thermal buoyancy effect because of
the small temperature difference between the inside and outside;
the main force causing ventilation is the wind. With openings on
both sides of the building, most of the air movement is across
the building and a large opening at the ridge has only a minor
effect.
A single slope roof building (MOF) (Fig. 6) uses the same
ventilation principles. Curtains or doors are used for most ven-
tilation control with a small, controlled opening at the upper
part of the high wall for cold-weather exhaust control. For more
information, see PIH-87, Cooling Swine; PIH-120, Non-Mechanical
Ventilation of MOF Swine Buildings; and PIH-60, Mechanical Venti-
lation of Swine Buildings.
Fan Ventilation
A fan system provides the power to direct the air where it
is needed to get proper distribution. Additional inlets may be
needed depending upon the building width.
The incoming air is directed by the design of the inlet to a
predetermined direction and location. With an exhaust system, the
fan creates a negative pressure in the building, and air enters
at planned inlets at a speed sufficient for mixing with the
inside air before it reaches the pigs. The mixed and partially
warmed air should not drop too quickly into the resting area.
In a positive pressure system, the fan blows into a duct
system which is used to distribute the air evenly throughout the
building.
Combinations of exhaust and pressure systems, sometimes
called neutral pressure systems, use one fan on the inlet and
another on the outlet.
Fan systems are more precise and can control ventilation to
a greater degree than natural ventilation systems, but they
require more electricity to operate. The large fans needed for
summer ventilation can easily be automated, but require signifi-
cant amounts of electricity to operate.
In colder climates some producers use fans in the winter to
control humidity and odors and use natural ventilation for the
remaining months of the year. To successfully ventilate with the
winter fans, all openings except for the planned air inlets, must
be closed when the fans are being used.
All-in/All-out Concept
One management option to reduce the risk of disease is the
concept called all-in/all-out. The entire group of pigs in a room
is removed so the room can be given a thorough cleaning before
bringing in the new animals. Instead of the growing-finishing
building being one large room, it is divided into smaller rooms.
At a minimum, this would be divided into a growing room and a
finishing room.
Depending on the frequency of farrowing, there might be a
need for 4 or 5 rooms. Several rules of thumb have been sug-
gested. One is to have no more than 300 pigs in a room. Another
is to put no more than 2 wk. of production of pigs in a room.
Careful planning is necessary when adopting this concept, because
it requires more initial investment and more exact scheduling.
Summary
No one growing-finshing unit design fits the needs of all
producers. When selecting a unit, consider the total system
including such things as production efficiency, initial invest-
ment, climate, labor and management time available, manure han-
dling, nearness of neighbors and your cropping system. Many
farmers are keeping detailed records today and that is certainly
providing much needed data in selecting facilities as well as
keeping account of production and efficiency parameters. Even
though a building may cost more initially, production efficiency
can make it more cost-effective in the long run.
The type of unit your neighbor has, or a unit successful in
another climate, may not fit your situation at all. Try to pick a
unit that will work well for you.
REV 6/91 (5M)
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Figure 1. Open front outside apron building with gable style roof.
Figure 2. Open front outside apron building with single slope roof.
Figure 3. Floor layout for open gutter unit. Gutter is either
flushed or scraped.
Figure 4. Partially slotted floor building with a single row of pens.
Figure 5. Insulated roof option for single row of pens, partial slats.
Figure 6. Single slope roof, partial slats building.
Figure 7. Totally slotted floor building with a center alley.
Figure 8. Insulated roof option for two rows of pens, total slats.
Figure 9. Continuous, sloped center chimney building.
Figure 10. Intermittent square chimney building.
Figure 11. Year-round fan ventilated building. Minimum insulation
under the roof reduces heat pickup in hot weather.
Figure 12. Approximate climate zones.
Figure 13. Hairpin shape of gravity drain gutter.
Figure 14. Two uninsulated curtain options.
Figure 15. Two insulated curtain options.
Figure 16. Two insulated door options.
% Figures are available in hard copy..
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Cooperative Extension Work in Agriculture and Home Economics,
State of Indiana, Purdue University and U.S. Department of Agri-
culture Cooperating. H.A. Wadsworth, Director, West Lafayette,
IN. Issued in furtherance of the Acts of May 8 and June 30, 1914.
It is the policy of the Cooperative Extension Service of Purdue
University that all persons shall have equal opportunity and
access to our programs and facilities.
.