HOUSING                                           PIH-11


                    Swine Growing-Finishing Units

Vernon M. Meyer, Iowa State University
L. Bynum Driggers, North Carolina State University
Kenneth and Debra Ernest, Sidney, Ohio

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

     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.


     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

     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

Table 1. Suggested temperature range for growing-finishing pigs.
Age, wk.   Pig weight, lb.   suggested temperature range,o F
 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

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.
Gas                                                           ppm
Ammonia                                                        10
Carbon dioxide                                               3000
Hydrogen sulfide                                                5


     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

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

     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


     Use the indicated insulation values for your climate,  (Fig.
12 and Table 3).

Table 3. Suggested R-values for enclosed buildings.
Climate                               Suggested R-value
                             Wall                       Ceiling
Cold                         14-20                       25-35
Moderate                      14                         14-20
Mild                           5                           5

     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.
Pig weight,        Enclosed            Shed with outside lot
lb.                building          Inside             Outside
                           ---------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


     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.
                                             Pig Weight
Item                                40-125 lb.        125-230 lb.
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

     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

     Vertical or horizontal bar gates or panels are suggested for
any  open  partitions such as over the slotted area or open flush

     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

     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

     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

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

     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

     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


     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-

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

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

     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

     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.


     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)

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..

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.