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Chapter 15 Production systems for growing pigs.


Over the past decades, pork production traditionally consisted of three types of enterprises: farrow-to-finish, feeder pig production, and finishing feeder pigs to slaughter weight. Many traditional pork production enterprises included one of two phases in which pork producers either produced feeder pigs or finished feeder pigs for slaughter. The feeder pig producer bred sows, cared for nursing sows and their piglets, and produced weaned pigs that were kept in nurseries until the pigs were 8 to 12 wk old. The second phase of these production enterprises was the feeder pig finisher. These units took the feeder pigs from 18 to 23 kg (40 to 50 lb) body weight up to a market weight of 100 to 114 kg (220 to 250 lb). These long-held standards have changed in some markets during the past decade. A major change is the gradual increase in the market weights over the last 50 years. The average market weight is now about 118 kg (260 lb)--and rising! The weights and ages of pigs in each stage are evolving in U.S. modern pig production.

The traditional stages of weaned, growing pigs are nursery, grower, and finisher. Farrow-to-finish producers have all stages under their direct management. A pig producer who has just nursery, just grower-finisher, or both nursery and grower finisher is often called a "grower."


Certain production practices may be found in modern, growing pig production systems. These include segregated early weaning (SEW) and all-in-all-out systems of disease control; use of superior genetics from a healthy source; use of diets formulated to meet pig nutrient needs (probably on a least-cost basis); and a willingness to supply capital, equipment, or labor to allow the production system to succeed.

Producers must consider several factors in determining which finishing system will work best for a given operation:

1. Available capital

2. Through-put of pigs required

3. Environmental situation (laws, regulations, farm situation)

4. Nearest neighbors and the need to reduce offensive odors

5. Need to capture manure nutrients for crops

6. Skills of the stockpeople

7. Availability of bedding

8. Availability and cost of power

9. Market location and market requirements

10. Labor


Average market weights have increased because of packer requirements for heavier hogs. Packers discovered that for some genetic lines, heavier pigs were still lean. Economics dictate that the labor to process a carcass is quite similar for a 300-lb (136 kg) pig and a 220-lb (100-kg) pig. Thus, heightened labor efficiency and greater plant through-put of salable pork are achieved with heavier pork carcasses as long as the heavier carcasses are relatively lean. Packers' demand for heavier carcasses is achieved by the grower through two general methods: (1) holding pigs in finishing longer and/or (2) genetically selecting for increased rate of lean weight gain.

If a packer demands (on a short time schedule) that the best price will be paid for pigs with a heavier body weight, the grower has no choice but to increase the time pigs spend in the finishing phase. These added days are very costly, however. The pig's feed efficiency gets progressively worse as it gets heavier.

Breeders are currently selecting not just for greater average daily gain (ADG), but for greater average daily lean gain (ADLG). If the production facilities are scheduled with a fixed time in finishing, the grower will increase the final market weight as selection for increased ADLG progresses.

While the present market weight average is 250 to 260 lb (114 to 118 kg), the U.S. industry is moving toward the day when market weights average closer to 300 lb (136 kg).


Sows in the wild wean (separation of mother and piglets) their piglets at a highly variable age from a few days to 6 mo of age. Most wild sows gradually wean the litter over several weeks or months, with the average weaning age between 3 and 6 mo of age. In the last century, people who weaned pigs at 8 wk of age were considered as practicing "early weaning." In the 1950s through the early 1970s, it was considered "early weaning" to wean pigs at 4 wk of age. Economic models and biological studies then began to investigate very early weaning, starting at birth. Machines were built to provide hourly milk to the piglets. Most of these early efforts to wean piglets at 1 to 21 d of age were not widely adopted due to piglet health problems, problems with feeding liquid diets, and an incomplete understanding of piglet nutrient requirements.

The 1990s combined better diets with economic models and drove weaning age down to 14 to 19 d. Piglet diets improved even more in the 1990s and a discovery was made about piglet health: Piglets that were taken from their mothers at a very early age (5 to 15 d) had superb health. This technique is called segregated early weaning (SEW). The conventional wisdom is that SEW pigs have a high level of passive immunity, but they do not have enough time on the sow to be exposed to pathogens. Maternal antibodies are transmitted from the sow to the piglets through colostrum; these maternal antibodies last at least 21 d. Removing the piglets from the sow before she infects them and while they still have passive immunity makes sense. SEW can be used to produce healthy pigs. SEW is less effective for certain diseases, but works quite well for others.

Growers can now buy SEW piglets. This is a new concept because the traditional feeder pigs are 40 to 50 lb (18 to 23 kg) and the SEW pigs are 5 to 15 lb (2 to 7 kg) and could be 5 to 19 d of age. Furthermore, they may be taken off the sows and transported to a distant grower, a relatively new practice.


The concept of contracting, while familiar to the broiler industry, is relatively new to the pig industry. The general concept and the most common model is that the grower owns the land and buildings and supplies the labor to care for the pigs. Another individual or corporation owns the pigs and supplies the feed and veterinary care. In essence, the grower has minimal risk and is paid a flat fee, perhaps with a bonus for good pig performance. The owner of the pigs assumes more market risk, but while there is a greater risk of losing money, there also is a much greater chance of making a profit. The owner of the pigs can put more money in sow units as a result of the contract grower sharing the total capital expense of production.

Contracting changes people's motivation. Contract growers may show less care of the pigs because they do not own them. Or, alternatively, they may show greater care for the animals because of the contractual arrangement.

The design of facilities and management of the animals in a contract facility is a concern to both the owner of the pigs and the contract grower.


Wean-to-finish buildings are becoming more popular on new farms in the United States. In the 1980s, some farms had three buildings from weaning to market: nursery, grower, and finisher. The grower and finishing buildings were then combined to make grow-finish buildings. In the wean-to-finish barn, one building is used from weaning to market for about 26 wk. In the old models, nurseries housed pigs for 4 to 9 wk and the pigs spent the remaining weeks in the growing-finishing building (17 to 22 wk).

An analysis of the economics of the nursery-growing-finishing period favors the newer wean-to-finish system over conventional two-stage buildings (Stein, 1999). Wean-to-finish systems have lower transportation costs, lower animal health costs, better pig survival, lower water costs, and lower waste management costs (see Figure 15-1). The ADG tends to be faster, but is not significantly better for wean-to-finish pigs (see Table 15-1) because, unlike conventional systems, there is no set-back in growth associated with moving and mixing pigs with the wean-to-finish buildings. The inefficient space utilization during the early weeks is a disadvantage of the weanfinish concept but may be offset by improved productivity.



Baxter (1984) reported on the care of growing pigs in medieval times in a system that involved a night-time containment of pigs in a fenced area in combination with daytime foraging of tree mast (acorns, especially). In this system, the herder blew a horn to signal feeding in the evening. Pigs would come running out of the forest and gather in the fenced-in area for a feeding of grains or food scraps. The pigs would bed-down at night in this protected enclosure and were released in the morning to forage again. This system conditioned the pigs to a temporary containment that provided a convenient collection point for the occasional human dinner-time harvest.

Pig housing then moved to full-time containment in pastures, lots, or buildings. In modern pork production, the greater the building investment, the greater control the owner has over pig performance and through-put. From an economic point of view, buildings and pens are depreciated over different time scales, depending upon their expected useful life. If one building costs $100,000 and lasts 10 yr, its per-year depreciation is $10,000. A $200,000 building that lasts 20 yr has the same annual charge for depreciation.

Some facilities that seem inexpensive are actually very expensive. If a low-investment facility costs $50,000 and lasts only 4 yr ($12,500/yr charge), it is more expensive annually than a $100,000 building that lasts 10 yr ($10,000/yr). A facility's cost is determined by its per-year cost, not the total cost of the facility.

Building intensity is a term used to describe the relative concentration of production in the facility. Generally, but not always, buildings with a more intense production through-put are more expensive to build and operate.

The U.S. pig industry has almost come full circle in relative intensity of growing pig facilities. In the 1950s through the 1960s, the U.S. pig industry saw a clear movement to indoor systems for containing growing pigs. Pigs moved from the old-style sty with a simple wooden shelter to open-front buildings on concrete to entirely enclosed buildings. Briefly, in the late 1970s, buildings for finishing pigs were totally enclosed with a heater and mechanical ventilation. This building style is still in use in the northern Midwest and in Canada. In the core of the Midwest and southern parts of the country, however, a fully enclosed, mechanically ventilated, heated building was not needed (nor is such a building cost effective in southern climates) (see Figure 15-2).

From the totally enclosed building, the industry moved to naturally ventilated buildings. These buildings were operated more as a shaded structure in the summer and a poorly insulated building in the winter. Pig performance, air quality, and worker comfort were very good in these buildings. Some producers skipped the mechanically operated building phase and have used one of several styles of curtain-sided buildings ever since the 1970s.

The tunnel-ventilated building is a newer style of mechanically ventilated building. In this style, large fans operate on the ends of the building. One end uses either an air inlet or an evaporative cooling pad. The longer building sides have curtains. These curtains do not serve as ventilation inlets, but rather serve three purposes: (1) They let light in and add to pig and worker comfort; (2) they drop in the event of a power outage, thereby preventing pig loss due to lack of ventilation; and (3) they provide a lower cost for materials--a curtain costs less than a solid wall.


A typical modern building houses 1,000 pigs (_250). All pigs that arrive at the building are of a common age group and from a single genetic source. The building is emptied over a 3- or 4-wk period in five semi-truckloads (one truck holds about 200 pigs). The production schedule of the farm dictates how long the pigs are there and how many days or weeks they may be on feed. Final market weights are higher with more days on feed.

How does pig performance compare in different facilities? Table 15-2 shows that the pig performance was much better in the low-investment facility than in the high-investment building. Nicholson et al. (1995) conducted the study in Texas in the fall of the year when pig performance was high because the weather was relatively mild.

When the same sort of comparison was done in Iowa, a different outcome was found. Iowa pig performance was essentially equal in the indoor and the hoop-style buildings (see Table 15-3). Pigs in hoop-style buildings tend to grow at a slower rate and with a lower feed efficiency in cooler climates. Colder climates place a greater demand on pigs to use part of their feed for body warmth. In warm climates, productivity in hoops is likely to be at least equal to that in warm housing. Tables 15-2 and 15-3 illustrate that pigs can be raised successfully in a wide variety of housing systems.

Controlled data comparing pig performance in many systems are not available. Sometimes field data are not as reliable as data obtained in controlled studies, but field data may indicate general trends that might help producers make informed decisions.

The Cover-All Company in Canada reported field data on pig performance under different housing systems. In this report, all pigs were of similar genetics and they were fed similar diets. The modified open-front building--the standard high-performance building of the 1970s in the midwestern United States, produced the lowest pig performance. Pigs in a double-curtain building (curtains on two side walls) and in the hoop-style building appeared to have the best overall performance.


Alternative finishing becomes more attractive when the following conditions are present:

1. Less capital is available

2. Bedding is available

3. Labor and heavy equipment are available

Alternative production systems are being developed, in part, because every pork producer should want to build facilities with lower capital costs. Dealing with the large mass of dry or damp bedding is the most significant obstacle to development of bedded facilities. Additional advantages to bedded facilities compared with concrete slat buildings include:

1. Pigs on bedding show less tail biting than pigs on slats.

2. Pigs on bedding have fewer foot pad lesions than pigs on slats.

3. Pigs on bedding have fewer leg problems than pigs on slats.

4. Pigs on bedding in naturally ventilated structures tend to have fewer respiratory problems.


The most common type of finishing building in west Texas and western Oklahoma (present number of pigs finished is over 5 million/yr) and among newer U.S. buildings in other regions is a tunnel-ventilated building with total concrete slats. This building houses about 25 pigs/pen and is sized for 1,000 pigs (_200 head). Older (1 to 8 yr old) buildings in the region have a separate nursery and newer buildings are built as wean-to-finish buildings.

The most common, newer or alternative finishing system is the bedded, naturally ventilated, open-air building. Two styles showing some success are hoop buildings and turkey buildings. The hoop building is designed for 200 to 250 pigs; the turkey building is designed for 1,000 to 2,000 pigs. Systems of finishing pigs that have lost favor for various reasons include slatted-floor, open-air buildings; totally enclosed, mechanically ventilated buildings; partially slatted, partially solid-floored pens; and true pasture rearing of finishing pigs. It seems that the most successful buildings are either the totally slatted (often tunnel-ventilated) or bedded and open-air (but not really outdoors).

The newer alternative production systems for finishing pigs are best characterized by the hoop buildings or the scaled-up, former poultry house versions (see Table 15-4). Major differences in these newer, more successful systems include:

1. Use of large group sizes (one pen/building)

2. Use of corn stalks, wheat, or barley straw as bedding

3. Use of dry or wet-dry feeders

4. All-in-all-out systems

5. Use of superior genetics and healthy pigs

6. Utilization of dry bedding as a nutrient for crops

Concrete, Metal, and Wood Structures

Buildings in this category are referred to as total confinement buildings or indoor systems. Such buildings have fans that operate to draw in fresh air and exhaust stale air. They also have heaters in most climates and cooling systems in many buildings. Many of these buildings use total or partial slats for waste containment and removal.

Disadvantages of this type of building include:

* These buildings use the most energy of the alternatives.

* They are the most expensive to build.

* Pigs and workers are subjected to artificial light.

* The air environment is often poor, especially in northern areas in the winter months.

* Floors are often slotted, which is a challenge for pigs' feet and legs.

* Pig health is at risk during power failures.

* Once disease organisms enter, they spread quickly.

* Buildings emit odors through exhaust fans.

Advantages of the total confinement building include:

* They promote uniform pig growth.

* In some seasons, especially winter, the best feed conversion is obtained.

* Disease organisms can be kept out through strict biosecurity.

* Seasonal delays or performance problems are minimized.

* Waste can be contained and managed to recycle nutrients and reduce offensive odors.

* Buildings have a long life.

Indoor-Outdoor Lots

Structures in this category include facilities with an indoor, sheltered area and an outdoor run. The sheltered area is often constructed of wood posts or poles. The unit is sometimes called a pole shed.

Floors in these units may be earthen or concrete. On occasion, a slotted area is provided, more often on the outside run. One classic building style is referred to as the Cargill-style building. In this structure, the floor is concrete and is sloped from the shed to the outside concrete run. The sheltered area is usually bedded, but the outside run is typically not bedded.

The open-front building with an indoor and outdoor run is considered a facility that compromises cost and, therefore, productivity. Very few of the newly constructed buildings use this design, yet many thousands of pigs are raised in these buildings today.

Disadvantages of this type of building include:

* Producers are unable to regulate the environment.

* They promote poor pig health.

* They are intermediate in cost to build, but are more costly than the deep-bedded, hoop-style buildings.

* Pig performance is intermediate to total confinement and the better, bedded facilities.

* Most open-front facilities emit an offensive odor due to accumulating waste that is infrequently removed.

* Waste recycling is not on-going, but periodic.

* Workers experience the variable outdoor environment (especially the extremes of winter and summer).

Advantages of this type of building include:

* Their construction costs are lower than those of total confinement buildings.

* Older buildings may be available at a reasonable cost.

* During mild weather, workers may enjoy working outdoors.

Hoop-Style Design

The hoop-style building is one of the newer-designed buildings for housing growing and finishing pigs. It is basically a deep-bedded building that is Quonset shaped. The Quonset shape provides a simple and inexpensive building. The hoop-style buildings house small groups of pigs (150 to 250 pigs) in one large pen.

The deep bedding may be a material such as wheat straw or corn stalks. Other local bedding materials may be used (cotton gin trash, rice or grass hulls, etc.). The bedding is first installed to a depth of at least 18 in. Bedding is then added over time to create a dry material on top with an underlying, fermenting material. The manure pack generates a fair amount of heat as it ferments and digests the waste. The dry bedding that covers the manure pack provides an insulation and odor-trapping function.

The construction of the hoop building includes an optional concrete pad in the front of the building that extends out to create a concrete slab on which equipment may be driven or pigs herded.

The walls of the structure are 4 to 6 ft tall and are typically wooden planks with posts sunk deep (below the frost line) for support. Metal pipes or trusses are fastened on top of the walls to make the hoop shape from one long wall to the other. A canvas or plastic tarp is drawn over the metal hoops.

Pork producers who have these hoop structures report great success in both pig performance and worker satisfaction. Because this building design is relatively new, there are no good estimates on the expected life of these structures. Several buildings are fully functional after 4 yr and their expected life is probably well over 10 yr.

Two main groups have utilized the hoop design: One group is from the plains of Canada (Manitoba and Saskatchewan) and the other group is in Iowa and Nebraska. Both groups report a positive outcome for the hoop building in terms of economics and producer satisfaction.

Disadvantages of this type of building include:

* Pig performance in northern climates is slightly worse than that of comparable indoor systems.

* The environment may be humid at some times of the year, causing condensation to drip from the bars.

* Flies may be a problem in the summer months.

* Because the social groups are large, pig fighting may continue for much longer than would occur in smaller, indoor groups.

* Removing manure can be very time-consuming (but probably not much more so than power washing an indoor unit and dealing with the effluent).

* Feed efficiency may be 10% to 20% lower in the hoop structure than indoors.

* Bedding use averages over 200 lb per pig per cycle or turn.

* Feed efficiency worsens in colder climates.

* Weight gain and fatness may increase in warmer climates.

Advantages of this type of building include:

* Very low capital cost is needed to build the structure.

* Well-designed and efficiently operated buildings provide a pleasant environment for pigs and workers.

* Pig mortality is reported to be low in the hoop building.

* Weight gains are comparable to those of pigs in indoor systems.

* The added bedding costs and poor feed efficiency are reported to be more than offset by the lower building costs.

Tent Design

The tent design is a variation on the hoop design. The tent system is a European design and is not in common use at this time in the United States. The side walls of the tent are made of stacked-up straw or bedding materials. Large, square straw bales are the most common material. The thick wall of bedding provides significant insulation from temperature extremes.

The top of the tent is often a triangular-shaped metal frame that is covered with canvas or plastic tent material. The facility is easily moved.

The floor is earth, with a healthy cover of bedding (more than 2 ft deep to start). Feeder and waterer numbers and space needs for the tent structure are just as those for the hoop structure.



Buildings and lots for growing pigs need to accommodate the needs and comfort of the pigs and the workers. The most common design has a center aisle with pens on each side. In wider buildings, having pens on just one side of the building and an aisle along one side is less efficient space utilization than to have a center aisle that serves two sets of pens (see Figure 15-3).

To overcome the inefficiency of the aisle, buildings have been built without an aisle. These general building layouts are shown in Figure 15-4.



For each of these buildings, calculations are based on a pen that is 6 x 3 m (20 ft x 10 ft) that provides 0.8 [m.sup.2] (8 [ft.sup.2])/pig for 25 pigs. The example building has a 0.8 m (2.5 ft) wide aisle. In the building on the left with an aisle and pens on just one side, the aisle represents 12.5% of the floor area of the building. For the middle building, which in this example is twice as wide, the aisle occupies only half as much space (as a % of total space). Aisles are considered by some people to be a waste of space because pigs do not occupy that space on a full-time basis. Building costs are increased proportionally by added aisle space.

The aisle is not an absolute necessity in the management and care of the pigs. In the building without aisles, workers can walk from pen to pen among the pigs to observe animal health. Alternatively, some buildings have a type of catwalk over the fencing material so people can observe the pigs from above. This requires a taller building and is an added cost.

The building configuration impacts how pigs are observed and handled. Even the fence height influences how the pigs are handled--if the fence material is too tall, it inhibits people from walking from pen to pen. If the fence material is too low, pigs will jump from pen to pen causing injury, excessive fighting, and even pig deaths.

Producers should consider how the pigs will be handled before the building is occupied. Pigs may need to be sorted, moved, and treated for illness. Provisions should also be made to accommodate dead pig removal.


Within the growing pig building, a sick pen (pen for congregating sick or injured pigs) is usually placed on the end of each aisle of pens (see Figure 15-5). Some newer farms put the sick pen in the center of the building, which reduces the maximum distance to walk or move sick pigs. Center pens are often warmer and are subjected to fewer drafts from open doors on the ends of buildings. However, placing the sick pigs in pens in the center of the building exposes more pigs to potential pathogens. In the absence of serious diseases, the sick pens should be smaller than an ordinary pen. Fewer than 0.5% of the pigs in a given building should be in the sick pen at any one time. Many modern buildings use the center pens for sick, injured, or smaller pigs; these pens are the same size as ordinary pens.



Many pork producers still finish pigs in open lots or in low-investment facilities (see Figure 15-6). The capital costs/yr for low- and high-investment facilities are often very similar. Low-investment facilities use equipment that is depreciated over 7 or 8 yr. A building is an asset that can be depreciated over 15 or more yr. Thus, the capital cost/yr may be similar if the low-cost alternative is about one-half the cost of the indoor unit. The general pen and feeder/waterer organization is used for both low- and high-investment facilities.


Hoop-style structures can be organized in a manner similar to that used in indoor units. Animal handling areas (chutes, scales, etc.) are typically outside the main building, rather than inside the building.

Hoop-style buildings are stocked differently than typical indoor facilities. Most often, the building holds 200 to 250 pigs in one large pen. The pen building has the required amount of feeding and watering spaces. The space requirements/pig have not been fully evaluated; however, the recommendation of 12 sq ft/pig is common; this space allowance supports good animal performance.

When several buildings are lined up on a single site, there should be a 40-ft space between them to allow for air movement and ventilation of each structure.



Standard pen layouts are most often rectangles. Rectangular-shaped pens are easy to construct and equip. If pens were round or odd-shaped, it would be difficult to align a series of pens.

Pigs use their space based on quantity and quality of space provided. A pen is a collection of individual components that come together to form a microenvironment for the inhabitants. Pigs experience the microenvironment in ways producers are only beginning to understand.

Standard equipment within the pen includes flooring, fencing, feeders, watering devices, resting places, and free space. Some farms now use enrichment devices to provide some entertainment for pigs during idle times. How pigs view the quality of space is largely unknown.


Flooring can be solid, solid and bedded, partially slatted, or totally slatted. Most solid floors use bedding of some sort. Baxter (1984) suggested that a good floor should:

1. Not cause injury

2. Not contribute to disease

3. Not cause discomfort or distress

4. Not be inconvenient (to humans)

In addition, a floor should:

5. Firmly support the pig's weight

6. Allow manure to drop through or manure moisture should be absorbed by bedding

7. Be easy to clean or self-cleaning

8. Not be slippery, but not too abrasive either


Bedding should provide nonslip footing, warmth, moisture absorbency, and a play or enrichment material. Bedding may also contribute to nutrients eaten. Bedded facilities provide the greatest comfort to pigs in terms of both physical and psychological comforts (bedding provides a substrate on which pigs can root). Pigs, however, can get by quite nicely without bedding if all their other physical and psychological needs are met.

Bedding materials vary in absorbency but should absorb a large amount of water/ unit of bedding weight. Table 15-5 lists the relative absorbencies of common bedding materials.

Most modern indoor units use partially or totally slatted floors. If the floor is partially slatted, as is the case in many open-front and curtain-sided buildings, the slatted area should be at least 25%, and preferably more than 33%, slatted. If less slatted area is provided, the pigs will soil the solid areas of the floor. A build-up of manure on the solid floor space is unsightly, unsanitary, and should be avoided.


Floor Materials

The anatomy and growth of the pig's foot are important features. Pig feet grow in an exponential manner--rapid growth is followed by a leveling off of toe width and length. The pig's inside toes are typically shorter than the outside toes. Toe pad lesions are found on the underside of either toe. Such lesions can be quite painful and should be avoided. A greater % solid area minimizes toe lesions. Rough floor surfaces add to the potential for foot pad lesions. A foot bath of 5% copper sulfate (4 lb/10 gal of water) that pigs walk through three times/wk will help heal toes with lesions. However, the real cause of the excess rate of lesions (such as floor type or condition) should be identified and corrected.

The % solid or the % void (the two measures are perfectly correlated) is an important measure of a slatted floor's features. A floor such as woven wire has a low % solid area and a high % void area. A flooring such as 6-in-wide concrete slats has a high % solid area or a low % void area. Example floors are given in Figure 15-7.

Younger pigs require a warmer and cleaner floor than do older pigs. This is because younger pigs have a less-developed immune system and a warmer temperature requirement (i.e., a higher lower critical temperature). Thus, younger pigs are more susceptible to disease microorganisms and are more easily chilled.

The trade-off in slatted flooring is between foot support and lameness on the one hand and warmth and cleanliness on the other (see Figure 15-8). The younger the pigs, the greater the need to separate the pigs from their feces and urine for health reasons. A floor with a low % solid area will clean better than a floor with a high % solid area. Larger pigs also have larger feet and they can push the fecal material through the flooring more efficiently than can younger pigs.

Older pigs require greater support for their feet and legs. They will have problems with lameness if their feet are not well supported. The best support is provided by flooring that has a large solid area. Concrete slats have the greatest solid % and woven wire has the least solid area of the common floor types (see Table 15-6).

The most common flooring material in U.S. commercial nurseries is woven wire that covers either the total floor surface or two-thirds of the floor surface. Newer nursery floors use plastic slatted material. Some of the plastic flooring contains a bactericide that retards bacterial growth. Concrete slats or partial concrete slat floors are the most common flooring for growing-finishing pigs in newer U.S. buildings.

In partially slatted buildings, the fencing near the solid flooring is often solid to create a warm, dry area. The fencing over the partial slats is often open materials to allow drafts and wind currents that keep the area cool and encourage elimination.


Fencing materials are chosen for their thermal properties, their ability to be sanitized, pen ventilation requirements, and durability. The choice of open or solid fencing is dependent upon the needs for ventilation and the thermal needs of the pigs in the building.

Common fencing materials include solid concrete, poured concrete with open wall slots, painted metal, wood, or plastic. The less porous the fencing and flooring material is, the better it can be sanitized.

What Is the Best Fence Height?

When choosing the height of fencing material, producers must take into account the ability of pigs to climb or jump over fencing, the cost of the fencing, and the ability of workers to climb over the fencing material as they care for the pigs. Clearly, if the fence height is lower, workers can more easily move from pen to pen. Lower fences generally cost less than taller fences. Pigs are curious animals and they will investigate the fence and may climb or jump from their home pen to the neighbors' pen. When a socially strange pig arrives in a new pen with an established social order, the residents will be aggressive toward the newcomer--they may even kill the "intruder." For this reason, the fence height should prevent pen-to-pen jumping.



In a controlled study, McGlone et al. (1990) examined how high nursery pigs can jump. Pigs were trained to jump over plywood walls cut to different heights. Some nursery pigs could jump 0.77 m (30 in) if they had some training. The naive nursery pig could not jump 0.61 m (24 in). When weanling pigs were acclimated from weaning to fences 24 in tall (Wadsworth et al., 1990), they did not jump over to the neighboring pens. Based on this work, Wadsworth et al. recommended that nursery fencing be 24 in tall. The researchers are not aware of similar work done for finishing pigs. However, some newer-styled finishing buildings in the United States use 24-in-tall fencing material with success.


The choice of an appropriate feeder is a critical decision. The feeder is usually depreciated for 8 yr but it is expected to last at least 10 yr. Because of the need for durable equipment, feeders are more often made from stainless steel and plastic rather than wood or steel. In small swine enterprises, many farmers traditionally construct and repair their own wood and metal feeders.

Pigs have a strong level of curiosity and they will investigate, chew, and root against the feeder and other objects in the pen. The feeder must be durable enough to withstand the constant manipulation.

The simplest way to feed pigs is to feed them on the floor. In this management system, the feed is spread on a concrete, solid floor (indoors or outdoors) or on an earthen floor outdoors. If this method is used, the feed should be spread out so each individual will get enough to eat. This method is used for early weaned pigs to get them to eat dry feed more easily (a little feed is spread on the floor or in a pan on the floor to get them to root and investigate and begin to eat). Outdoor sows or low-investment indoor sows can also be fed on the floor or even on the ground if cubes are used.

Feeders are used (1) to contain the feed in a sanitary manner, (2) to minimize feed wastage, and (3) to conserve space, especially in growing-finishing where effective floor-feeding requires much more space than a feeder occupies.

The amount of feeder space needed by pigs has largely been determined by trial and error on commercial farms with an eye toward providing ample, but not excessive, feeder space. Newer studies indicate that some competition for feeding spaces actually improves performance of the groups of pigs.

As a practical matter, feeder designs are based on the weight and size of pigs in their last days in the building or lot. The feeder space could be too large or too small and each has special problems. If the range of weights is from 15 to 45 lb, the feeder is designed to accommodate the head and shoulder size of the 45-lb pig (Figure 15-9). The farm will experience problems if the range of weights is too large in a given phase. Imagine the problems if the range of weights in a nursery is from 8 to 60 lb and if the feeder is designed for 60-lb pigs. The first problem is that some 8-lb pigs will live in the feed trough. This site, selected as a resting place, prevents other pigs from eating, and could result in soiled feed and injured or trapped pigs. Fixed design equipment is simply not flexible enough to accommodate pigs that change in body weight by eight-fold.

If the feeder is too narrow, pigs will not be able to feed easily. As they approach a weight and size that is too large for the feeder, the caregiver would notice abrasions, cuts, and open sores on the pigs' head and neck. This is a clear sign that the feeder hole is either too small or is improperly designed (perhaps with sharp edges).

The choice of the feeder space width (and other dimensions) is best made based on the ending weight and size of the pigs in a given building. Data based on estimated pig head sizes are presented in Figure 15-10, which shows that a group of 50-lb pigs would have head widths of about 5 in. Thus, one might conclude that the feeder space ought to be about 5 in x 5 in if it is a square hole; a round hole would need a diameter of at least 5 in.


The coefficient of variation is a percentage figure that is
adjusted based on the mean. To calculate the CV, use:

100 x SD/Mean = CV

where SD is the standard deviation. Uniformity is associated
with a low CV.


Producers must not only be concerned about the average ending weight, but also the range of weights in the group. Pigs in a given group at a common age have about a 20% coefficient of variation (CV) in body weight. On larger farms, the higher number of pigs available makes it easier to sort pigs by age and weight into uniform pens. Table 15-7 examines the relative variation and the range of pigs' weight. Even under fairly good conditions, the weight range may be from 40 to 60 lb for the average barn full of 50-lb pigs. Thus, the feeder space for the average ending weight of 50 lb should actually be for the upper end of the pigs in the barn, which may weigh 60 lb when they leave the nursery. The consequence for not meeting the needs of pigs for feeder space is injury to pigs and an equipment-induced limit on feed intake and weight gain.

The problem of wide ranges in body weights and head/shoulder sizes is more of a concern in the nursery than in growing-finishing. In growing-finishing, the growth curve levels off above about 100 lb and, therefore, the range of head and shoulder widths is less. The nature of the exponential growth curve is that the rapid growth during the nursery phase expresses itself as a rapid increase in head width. In later stages, however, the head width does not change as much.

To accommodate the wide ranges of pig body weights and head sizes, some feeders have an open trough. The open trough may be long enough to accommodate four or more pigs eating simultaneously when they weigh 15 lb, but only two pigs eating sidebyside when the pigs weigh 45 lb.

Traditional recommendations for feeder space requirements put the requirement at four to five pigs/feeder space, but more feeder spaces are needed shortly after weaning. Newer information challenges this standard.

The normal biology of the pig is disrupted at weaning when the pigs are separated from their mothers. During lactation, pigs of European origin have a very strong attachment to a single teat--they express teat fidelity (interestingly, Asian pigs such as Meishan have much weaker teat fidelity). When pigs are weaned, the caregiver provides fewer than one space/pig. To improve efficiency, pigs take turns eating out of a feeder. Previously, each pig had its own feeder (teat). Producers disrupt pigs' behavior when they move them to a dry feeder.

Former conventional wisdom suggested that producers should not limit feeder space because it would limit feed intake (FI) and average daily weight gain (ADG). Some competition at feeding or social pressure at the feeder actually can stimulate feed intake.

Table 15-8 shows data from a Texas Tech University study of 600 pigs. Growing-finishing pigs were given one, two, or three feeder holes in groups of 20 pigs/pen. With two feeder holes (one space/10 pigs), the pigs actually ate more feed and gained faster than when pigs had fewer feeder spaces. With the old standard of three feeder holes (one hole/six to seven pigs), there was no change in feed intake or ADG. From a statistical perspective, the F:G ratios and ADG for two and three feeder holes/20 pigs were similar.

The data described in Table 15-8 are for pigs fed from a dry, wooden feeder. The results are certainly likely to be different for each model of feeder on the market. The proper pig density/feeder space is very much worth refining in each microenvironment so the greatest economic return can be captured (see Table 15-9).

Wet versus Dry Feeders

A wet feeder refers to one of several styles of feeding equipment. Pigs used to be fed a slop--a suspension of food in water that was poured, shoveled, or otherwise delivered to the pigs. The old-style wet feeder was a trough in which meals were delivered. Wet feeders in the modern sense are feeders that provide the water source and feed source in the same compartment. Many of the modern wet feeders are designed to have the pigs apply the water to the feed or the feed to the water trough. In any case, many argue that "wet feeding" improves F:G ratios and allows more pigs to occupy a feeder space because pigs can eat more quickly from a wet feeder than from a dry feeder (which they have to alternate between feeding and walking over to water). Wet feeders may also conserve water.

The conventional European view is that wet feeding is the most economical approach. In the United States, wet feeding gets mixed reviews but is often recommended for pigs over about 50-lb body weight. A Texas Tech University study showed that in the nursery phase, daily weight gain and feed-to-gain ratios were lower in pigs fed from wet/dry feeders than from dry feeders (see Table 15-10; McGlone and Fumuso, 1993). The resulting ending weight for nursery pigs on the wet-dry feeder was 2 to 3 lb lighter than that for pigs on the dry feeders. The lower final nursery weight would be very costly to the pork producer. An average nursery ending weight that is 1 lb higher should translate into 2 or more lb heavier average market weight, given the same number of days on feed. However, in the finishing phase, results can be quite different. In Texas Tech University studies (unpublished), wet/dry feeders in finishing caused an increase in ADG of 14% and about the same feed efficiency.

In comparison, a rectangular, stainless steel feeder and a plastic, round feeder yielded similar pig performance. Given equal pig productivity, the decision on feeder model should be based on cost, durability or longevity, and ease of adjustment. Producers prefer feeders that require little adjustment and still deliver adequate feed with little waste.

Feeder models vary considerably. Pig performance must be determined for each feeder. In addition to the variation from one feeder model to another, feeder manufacturers change design features regularly in an attempt to improve pig performance and sales of their feeder.


Pigs require water to sustain their life and to grow. The nature of the watering device can impact animal growth and development. Pigs cannot live without water for very long; they suffer if they are without water for more than a few hours. Water deprivation for 12 to 24 hr has significant negative effects on pig behavior, feed intake, and growth.

In most situations, growing pigs should be given ad libitum access to water. The water should be free from minerals, bacteria, and other contaminants. Gilbert Hollis (1996) of the University of Illinois reports that water intake is at least twice the feed intake. The water intake for growing pigs is given in Table 15-11.

Some systems provide water in set watering bouts. Some systems provide water only when feed is delivered. These meal-fed and interval-watered systems are more common in Europe where pigs are more often limit-fed than in the United States where most pigs are fed ad libitum. When water is available in intervals, it should be left on for at least 30 to 45 min at a given time. Water should always be available when pigs are feeding.

Water flow rate has a strong influence on water consumption. If water pressure is too low, pigs will not be able to consume sufficient water, they will eat less feed, and they will grow slower. Jerry Bodman at the University of Nebraska suggests the minimum flow rate for waterers should increase with pig size:

Nursery pigs 0.23 l/min (0.06 gal/min)

Grower pigs 0.45 l/min (0.12 gal/min)

Finisher pigs 0.72 l/min (0.19 gal/min)

Pedersen (1994) suggests a greater flow rate for growing pigs (from 0.5 to 1.2 l/min). The European systems of limit feeding should require greater water flow rates because pigs can be fed water in meals rather than ad libitum. Water flow rate is clearly proportional to the pressure in the water line. Water pressure in the line should be 10 to 80 psi. Some nursery waterers may limit water intake in the 2 to 5 psi range. At this low pressure, pigs' water intake is limited and feed intake and growth will be proportionately reduced.

Watering devices come in various forms, including streams, a trickling hose, nipples, cups, and troughs. While most waterers are fixed against a wall, a newer style of waterer swings from the center of the pen. Pigs gain some enrichment or entertainment value from the swinging waterers and farmers report that the swinging waterers conserve water. Recent research at the University of Nebraska (Brumm and Dahlquist, 1997b) showed that the Trojan WaterSwing reduced water use by 11.1% and reduced manure volume by 16.2%. This is an advantage in the management of manure because wasted water is a large volume of the effluent volume. Anything that can be done to reduce water waste is welcome. However, the total manure nutrients are not reduced simply because of a reduced water volume--the manure is less dilute but contains the same total mass of nutrients that must be dealt with.

The Midwest Plan Service (1987) requires one waterer/10 nursery pigs and one waterer/ 15 growing-finishing pigs. If more than one waterer is used/pen, they should be spaced at least 12, 18, and 36 inches apart during nursery, growing, and finishing phases.

The height of the waterer should vary as the pigs grow. The desired height of the waterer varies depending on whether the waterer has a large or a small angle (90[degrees] or 45[degrees]). As pigs grow, the waterer should be raised to the pigs' shoulder or head height so that drinking is easy and comfortable (see Table 15-12).

Water can contain contaminants that limit water consumption. McFarlane (1995) gives values for various common contaminants in Table 15-13. He also provided a few alternatives if quality water is in limited supply on some farms. Among the alternatives to conserve water are recycling water from lagoons to the building flush systems; reducing water pressure to a minimal level to reduce water waste; revitalizing the wells on the property if they are older; and installing a filter or water treatment system. Newer swing waterers may also conserve water.


Pigs grow in an exponential manner, with the exponent of the curve less than 1.0 units. The general nature of pig growth follows a pattern of rapid early growth followed by a leveling-off of the growth rate. Not only does pig weight follow this pattern, but pig body size and shape follow the same pattern (see Chapter 8).

Groups of pigs require different space requirements than those previously discussed for individual breeding animals. The bodies of a group of pigs require a certain amount of space, referred to as occupied space. The space in a pen that remains is called free space. The amount of space pigs occupy depends on their posture and behavior. Pigs require less space when they are standing than when they are resting. Resting on their side (lateral recumbency) requires less space than does lying on their belly/chest (sternal recumbency). At any given time in a group of pigs, individual pigs are standing, walking, lying in lateral recumbency or sternal recumbency, or sitting. At times, pigs interact socially in various manners; these behaviors require even more space, referred to as social space.

Seaton Baxter (1984) described the amount of space pigs occupied in different postures. The equations are plotted in Figure 15-11. Pigs of about 250-lb body weight require about 6 sq ft for their bodies to rest on while lying down. At 250 lb, pigs require about 20% less space while standing or lying on their sternum than when they are lying on their side.

Pigs vary their behavior with time of day. Depending upon the effective environmental temperature and other components of the microenvironment, pigs generally show a diurnal cycle in behavior. A Texas Tech University study showed that pigs were least active around 0100 hours. At this point in the daily cycle, the pigs occupy the greatest amount of space because the greatest numbers of pigs are sleeping or resting (or the greatest number of pigs are assuming the posture that takes up the most amount of space). The amount of free (unoccupied) space is least around midnight and the most space is available shortly after noon when the most pigs are standing.


The cycle in pig behavior might lead some caregivers to think that pigs are not crowded when, in fact, they are. If the pigs are observed during the day, the caregiver should understand that even less space will be unoccupied or free in the evening when most pigs are lying down.

The amount of unused or free space increases with increases in group size. Figure 15-12 shows data on behavioral measures of space utilization are presented. Research has documented that if all the free space is removed, reduced feed intake and reduced weight gain will result. Attempts to add antibiotics or increasing nutrient density to compensate for the lower feed intake have failed to restore pig performance to the level of the "uncrowded" pigs.

McGlone and Newby (1994) conducted a study in which some or all of the free space was removed. Results showed that removal of 50% of the free space did not cause a pig performance problem. However, removal of too much of the unused or free space did result in a slow-down of ADG, largely due to a reduced feed intake (see Table 15-14).


The traditional space requirements were established with relatively small group sizes (less than 10 pigs/pen). When larger group sizes are used, there is a greater amount of shared, unused, or free space. Removal of some (up to 50%) of the free space has no negative performance consequence. The findings reported in Table 15-14 were confirmed in work at the University of Nebraska, indicating that 7 sq ft/pig is adequate for maintenance of economical pig growth (Brumm and Dahlquist, 1997a).

The space needs for heavier pigs can be estimated based on the data presented in Figure 15-11. Pigs up to 250-lb body weight and in small group size (less than 20 pigs) require 8 sq ft/pig. Larger group sizes, especially those over 50 pigs/pen, and pigs up to 300 lb-body weight may need only 8 sq ft/pig rather than the 9 sq ft/pig needed in smaller group-size pens. Traditional and newer estimates of space needs for growing pigs are given in Table 15-15.

Space needs for pigs in outdoor lots should be based more on local performance standards than by hard-and-fast numbers. When the weather is cold, less space in outdoor lots is acceptable. When the weather is hot and dry, less space is needed than when the weather is hot and wet. The cleanliness of the pigs and their health will help determine the space needs. Recommendations for space needs for pigs kept in sheds and lots (inside and outside areas) are given in Table 15-16.


The appropriate or best group size is difficult to determine. Every reasonable group size has been tried on farms with varied success. The traditional recommendation is to keep pigs in group sizes of 30 pigs or less. Group sizes of 40 to 100 pigs/pen have more problems with injury and mortality. A study at Texas Tech University indicated that growing-finishing pig mortality was 3.5% or less for group sizes of 10 or 20 pigs/pen. For 40 pigs/pen, however, the mortality was 10%. Similar results have been reported.

Recent work, however, has caused reconsideration of the general recommendation to keep group sizes under 30 pigs/pen. Pigs have been housed in groups of 150, 200, 400, or even over 1,000 pigs/building in a single pen. In these few case studies, pig mortality and productivity were comparable or, in some cases, even better than the traditional 20 to 25 pigs/pen found on many farms. Field trials have been done with 450, 1,000, 1,500 and 1,600 pigs/building in a single pen. In each case, pig productivity was equal to or better than that for pigs in traditional systems with 25 pigs/pen. How could this be? What mechanisms might be at play in large social groups? Further research is needed.

There is a limit to how many pigs a given pig can recognize and remember. This number is not known, but estimates vary that a given pig can recognize from 6 to 40 individuals. If pigs are regularly bumping into strangers, they experience social stress. When pigs live in very large group sizes, they establish smaller social groups that function as gangs of pigs. Each gang has a territory that it roams over. With this behavior, pigs do not often bump into unknown pigs. If this theory is correct, it would argue to spread feeding and watering stations over the large barn to prevent pigs from having to travel great distances for nutrients and to prevent unwanted and negative social interactions. The broiler industry, with thousands of chickens/barn, has utilized this concept for decades.



Loading chutes are needed to move pigs from buildings or lots onto trucks or trailers. If the loading chute is well-designed, pigs should flow like water through the chute. In well-managed, double-wide chutes, pigs can walk at a speed of over 1,000 pigs/hr. Features of a well-designed chute include:

* Fences should be strong and well-constructed.

* Fences can be solid or mesh as long as the mesh does not throw shadows on the floor.

* Lighting should be uniform.

* A straight chute is preferred to one that bends.

* Sharp, angled turns should be avoided.

* If a turn is required, a rounded fence is preferred.

* Cleats on the floor should be spaced as appropriate for the size of the pigs to be moved through the chute.

* If more than 600 pigs/hr are to be moved, a double chute should be provided.

* Chutes should not contain drafts.

Most nursery and growing-finishing barns should be able to have loading chutes that exit in a straight direction out of the building. It is a good idea to have the chute covered to avoid drafts, uneven light distribution, and outside disturbances. Nothing stops indoor-reared pigs more effectively than to be loaded in the early morning with the sun shining through the chute and a draft hitting them in the face. These conditions should be avoided.

Figures 15-13 and 15-14 present two loading chute designs. Figure 15-13 shows a double chute that is nearly straight. Some producers favor the slight bend in the chute so that pigs at the entrance to the chute cannot see the truck and activity at the chute-truck juncture.

Figure 15-14 shows a circular chute design. The circular design for the pre-chute area allows for a great number of pigs to enter the loading chute.

A funnel-shaped design for the pre-loading area does not work very well. As the funnel narrows, pigs get wedged at their shoulders and they cannot move forward. A dog-legged shape actually allows pigs to move more quickly than does a funnel-shaped entrance.




Pork production systems have changed dramatically over the past decades and continue to do so. This chapter focused on the production practices currently used for grower-finishing pigs. Changes in grower-finisher pig standards, including increased slaughter weights and earlier weaning, have accompanied the evolution of different types of housing, facilities, equipment, and marketing. Choices in building styles, ventilation systems, building and lot layouts, pen layouts, and types of fencing, flooring, bedding, feeder design, and waterers were described. Space needs of pigs and appropriate group size, from the standpoint of animal comfort and optimum performance, were discussed, and the latest research-based recommendations were provided. Finally, the design and characteristics of loading chutes needed for movement of pigs from pens or lots to vehicles for transport was addressed in terms of animal comfort and efficient marketing.


1. What are the trade-offs when producers decide upon low- or high-investment finishing facilities?

2. Why did wean-to-finish systems begin to flourish in the late 1990s?

3. How do the thermal needs of weaned pigs from an SEW unit weaning at 7 d differ from the needs of pigs weaned at 21 d in a conventional system?

4. How do the air temperature and space allowances vary for a wean-to-finish building compared with a conventional nursery? Should the wean-to-finish building be managed differently when nursery-age (weaning through 10 wk of age) pigs are present?

5. What effect does the production system have on pork eating quality, if any? (Search the literature and the Web for answers to this question; note the work of L. L. Hansen from Denmark and J. Gentry from the USA).


Baxter, S. 1984. Intensive Pig Production. Granada Publishing Ltd., London.

Brumm, H. and J. Dahlquist. 1997a. Effect of floor space allowance on barrow performance to 300 pounds. University of Nebraska Swine Report.

Brumm, H. and J. Dahlquist. 1997b. Impact of feeder and drinker designs on pig performance, water use and manure production. University of Nebraska Swine Report.

Brumm, M., J. D. Harmon, M. C. Honeyman, and J. R. Kliebenstein. 1997. Hoop structures for grow-finish swine. MWPS AED 41.

Hansen, L. L., A. E. Larsen, M. Hammershoj, P. Sorenson, and J. Hansen-Moller. 1999. Influence of aromatic components from pig manure on odour and flavour of cooked chicken meat. Meat Science. 52:325-330.

Hollis, G. 1996. University web page ( Univ. IL.

Hyun, Y., M. Ellis, and R.W. Johnson. 1998. Effects of feeder type, space allowance, and mixing on the growth performance and feed intake patterns of growing pigs. J. Anim. Sci. 76:2771-2778.

Hyun, Y. and M. Ellis. 2001. Effect of group size and feeder type on growth performance and feeding patterns in growing pigs. J. Anim. Sci. 79:803-810.

Kornegay, E. T. and M. D. Lindemann. 1984. Floor surfaces and flooring materials for pigs. Pig News and Information. 5:351-357.

Larson, M. E. and M. S. Honeyman. 2002. Performance of pigs in hoop structures and confinement during summer with a wean-to-finish system. Iowa State University web publication.

McFarlane, J. 1995, August. How to swell your water supply. Pork '95.

McGlone, J. J., T. E. Held, and S. Hayden. 1983. Physical and behavioral measures of feeding space for nursery-age swine. In: Proc. Western Section of ASAS. 34:66-68.

McGlone, J. J. and C. Fumuso. 1993. Performance of nursery pigs using a rectangle, round or wet/dry feeder. Texas Tech University Agricultural Sciences Technical report No T-5-327. p. 42.

McGlone, J. J., T. Hicks, R. Nicholson, and C. Fumuso. 1993. Feeder space requirement for split-sex or mixed-sex pens. Texas Tech University Agricultural Sciences Technical report No T-5-327. pp. 45-46.

McGlone, J. J. and B. Newby. 1994. Space requirements for finishing pigs in confinement: Behavior and performance while group size and space vary. Appl. Anim. Behav. Sci. 39:331-338.

Midwest Plan Service. 1987. Structure and Environment Handbook. MWPS-1.

Nicholson, R. I., J. J. McGlone, and R. T. Ervin. 1995. Economic comparison of pig feedlot housing facilities in the Southern high plains of Texas. TX J Agric. Nat. Resour. 8:19-26.

Olsson, O. 1981, December. Water supply system for pigs--drinking from nipples.

Pedersen, B. 1994. Water intake and pig performance. Teagasc Pig Conference, Fermoy, Ireland.

Purdue University. 2002. Pork Industry Handbook. Cooperative Extension Service. West Lafayette, IN.

Stein, T. 1999, October 15. The new economics of wean-to-finish production. National Hog Farmer. pp. 38-42.

Wadsworth, J. R., B. Owen, and J. J. McGlone. 1990. Partition height requirement for nursery-age pigs. Texas Tech University Agricultural Sciences Technical report No T-5-283. pp. 67-68.

Wolter, B. F., M., Ellis, S. E. Curtis, E. N. Parr, and D. M. Webel. 2000. Group size and floorspace allowance can affect weaning-pig performance. J. Anim. Sci. 78:2062-2067.

Wolter, B. F., M., Ellis, S. E. Curtis, N. R. Augspurger, D. N. Hamilton, E. N. Parr, and D. M.

Webel. 2001. Effect of group size on wean-to-finish production system. J. Anim. Sci. 79:1067-1073.


North Dakota State University provides a list of agricultural engineering publications at:

Some swine education and extension sites are found at:

University of Illinois:

University of Nebraska: porkpage.htm

Oklahoma State University:

Kansas State University: swine.htm

North Carolina State University:

Purdue University:

Texas Tech University:


Plans for handling facilities are found at Temple Grandin's home page:

For information on hoop structures:
TABLE 15-1
Comparison of Pig Performance and Economic Returns for Conventional
Two-Stage Buildings (nursery building plus a growing-finishing

                                            FACILITY TYPE

                                   FINISHING       WEAN-TO-FINISH

Number of sites                      68                  52
Starting weight, lb                   9.5                 9.5
Ending weight, lb                   255                 270
ADG, lb/d                             1.37                1.45
Feed intake, lb/d                     3.62                3.8
Feed: gain ratio                      2.64                2.62
Mortality, %                          5.5                 3
Building cost/pig space, $         $162                $187
Comparative profit, $/pig      Set to 0                 +$9.67

Source: Adapted from the Knowledgeworks, Inc. database (Stein, 1999).

TABLE 15-2
Comparison of Pig Performance and Economic Returns for Mechanically
Ventilated and Sheltered Lots on Dirt in Texas.

                                      FACILITY TYPE

                             DIRT FLOOR,      INDOOR, FANS
                            OUTDOOR RUN,       AND HEATED
                            WITH SHELTER        BUILDING         SE

Number of pigs                 119               120             --
Starting weight, lb             52.8              52.8           --
Ending weight, lb              243.9             223.7          4.72
ADG, lb/d (a)                    1.7               1.5          0.02
Feed intake, lb/d (a)            6.1               5.5          0.11
Feed:gain ratio                  3.5               3.7          0.1
Mortality, % (b)                 3.4               2.5           --
Cost of production, $/lb        $0.42             $0.45          --

(a) Housing systems differ, P < .05.

(b) Four pigs died in the low-investment facility; three pigs died in
the high-investment facility.

Source: Adapted from Nicholson, McGlone, and Ervin (1995).

TABLE 15-3
Means ([+ or -] SE) for Pigs Grown in a Hoop-Style or Conventional
Facility in Iowa. Total Pigs Evaluated Was 583.

                                 FACILITY TYPE


Start wt, lb *     12.6 [+ or -] 0.17     11.9 [+ or -] 0.12
Ending wt, lb     259.6 [+ or -] 1.6       260 [+ or -] 1.1
ADFI, lb/d         4.43 [+ or -] 0.11     4.35 [+ or -] 0.08
ADG, lb/d *        1.63 [+ or -] 0.03     1.53 [+ or -] 0.02
F:G ratio *        2.71 [+ or -] 0.03     2.83 [+ or -] 0.03

* P 0.05 (a statistically-significant difference).

Source: Larson and Honeyman (2002).

TABLE 15-4
Relative Pig Performance and Costs of Construction for Different
Styles of Buildings for Growing-Finishing Pigs.

                       DOUBLE-                 CARGILL-    HOOP-
                       CURTAIN,    MODIFIED,   STYLE,      STYLE
                       TOTAL         OPEN-     INDOOR-     BEDDED
MEASURE                SLATS       FRONT       OUTDOOR     BUILDING

Construction cost,
  $/pig capacity       $180        $120        $80          $55
Mortality, %              3.6        10.6        1.12         2.2
Feed intake, lb/d         4.8         4.6        5.7          5.6
ADG, lb/d                 1.66        1.41       1.57         1.77
F:G ratio                 2.9         3.25       3.61         3.14

Source: Adapted from a compilation of field data from Canadian
company Cover-All Shelter Systems.

TABLE 15-5
Relative Absorbencies of Common Bedding Materials.

                                     LB WATER ABSORBED/LB
MATERIAL                             OF BEDDING MATERIAL

Pine wood chips                              3.0
Pine sawdust                                 2.5
Hardwood chips                               1.5
Ground corn cobs                             2.1
Wheat straw                                  2.2
Hay,chopped mature                           3.0
Peanut or cottonseed shells/hulls            2.5

Source: Values adapted from Midwest Plan Service publication (MWPS-1).

TABLE 15-6
Flooring Characteristics for Common Pig Floors.

FLOOR MATERIAL                         % SOLID     % VOID    ADG, KG/D

Concrete slat, 6-in wide, 1-in void      86%        14%         NA
Plastic coated, expanded metal           74%        26%        0.31
Woven wire                               40%        60%        0.33

                                         FOOT          RESISTANCE,
                                        LESION        [degrees]C x
FLOOR MATERIAL                          SCORES        [M.sup.2]/W

Concrete slat, 6-in wide, 1-in void       NA              0.073
Plastic coated, expanded metal           1.1              0.15
Woven wire                               1.9              0.12

Source: Adapted from Baxter (1984) and Kornegay and Lindemann (1984).

TABLE 15-7
Variation in Pig Weights for a Group of Pigs That Average 50 lb.
SD Is the Standard Deviation. CV Is the Coefficient of Variation
(calculated as 100 x (SD/Mean)). With 2 SD on Either Side of the
Mean, the Weights Represent 95% of the Pigs in the Group. CI Is
the Confidence Interval or the Range of Weights That Contains 95%
of the Data.

                         95% CI FOR WEIGHT
CV, %          SD        MINIMUM TO MAXIMUM

 5             2.5          45 to 55 lb
10             5.0          40 to 60 lb
15             7.5          35 to 65 lb
20            10.0          40 to 70 lb

TABLE 15-8
Effects of Feeder Space Allowance (feeder spaces/20 pigs) for
Finishing Pigs Fed from Dry Feeders.

MEASURE                     1           2           3

Number of pigs            200         200         200
Number of pens             10          10          10
Starting weight, lb       134.5       133.8       133.6
Market weight, lb         228.4       233.9       233.0
ADG, lb/d                   1.46        1.56        1.57
Feed:gain ratio             4.02        3.91        3.80
Feed intake, lb/d           5.68        6.02        5.82

                                       PROB. VALUES (a)

MEASURE                    SE        LINEAR       QUAD.

Number of pigs              --          --          --
Number of pens              --          --          --
Starting weight, lb       3.82         .87         .96
Market weight, lb         4.28         .223        .257
ADG, lb/d                  .042        .039        .096
Feed:gain ratio            .136        .137        .914
Feed intake, lb/d          .163        .59         .16

(a) P-values for the linear and quadratic effects of feeder space
allowance (spaces/20 pigs).

Source: Adapted from McGlone et al. (1993).

TABLE 15-9
Feeder Space Recommendations for Pigs of Various Sizes. The
Traditional Recommendations Are Based on the Midwest Plan Service
and the Pork Industry Handbook. Newer Recommendations Are Based
on Controlled Studies and Field Data.

                                        FEEDER SPACES OR SIZE

                                 TRADITIONAL       NEWER

Early weaned pigs, 7-18 lb       2 pigs/space      2 pigs/space
Nursery, 18-60 lb                3 pigs/space      5 pigs/space
Growing-finishing, 60-300 lb     5 pigs/space      10 pigs/space
Sows and boars                   1 ft/sow          19-24 in/sow

Source: Adapted from Midwest Plan Service and the Pork
Industry Handbook.

TABLE 15-10
Least Squares Means for Pig Performance When Exposed to Three Types
of Feeders During a 35-d Nursery Period (weaning at 29 d of age).

                                  FEEDER TYPE
MEASURE               RECTANGLE     ROUND      WET/DRY    SE      (a)

Number of pigs        120         120         120         --      --
Number of pens          6           6           6         --      --
Starting weight, lb    15.2        15.0        15.2       .23    .870
End weight, lb         38.0 (d)    37.8 (d)    35.2 (e)   .34    .008
ADG, lb/d               .65 (d)     .64 (d)     .57 (e)   .01    .014
Feed:gain ratio        2.02 (b)    1.97 (b)    2.32 (c)   .06    .035
Feed intake, lb/d      1.30        1.30        1.32       .02    .588

(a) P-value for treatment effect.

(b,c) Treatments in rows with different superscripts differ, P < .05.

(d,e) Treatments in rows with different superscripts differ, P < .01.

Source: Adapted from McGlone and Fumuso (1993).

TABLE 15-11
Water Intake for Pigs of All Sizes.

                          WATER INTAKE


25                         0.4     1.5
50                         0.6     2.3
75                         0.9     3.4
100                        1.0     3.8
150                        1.3     4.9
200                        1.7     6.4
250                        2.0     7.6
300                        2.1     8.0
400                        2.3     8.7
Pregnant sows/gilts        4.5    17
Lactating sows             6.0    22.7
Boars                      4.5    17.0

TABLE 15-12
Recommended Nipple Waterer Height (in) above the Floor.

AGE OR STAGE      90[degrees]ANGLE   45[degrees]ANGLE

Nursing piglets         4-9                6-12
Nursery                 9-16              12-18
Growing                16-21              18-25
Finishing              21-26              25-30

Source: Adapted from Pedersen (1994).

TABLE 15-13
Limits of Some Common Water Contaminants for Water
Sources for Pigs. Zero Contamination Is Preferred.

ITEM                               MAXIMUM ALLOWED

Hardness; calcium carbonate, ppm         180
Total dissolved solids, ppm            <3,000
pH                                       5-8
Coliforms, number/100mL                   1
Algae                                   None
Nitrate, ppm                             300
Sulfate, ppm                           <3,000
Chlorine, ppm                            300
Copper, ppm                              0.5
Fluorine, ppm                             2
Arsenic, ppm                             0.2
Cadmium, ppm                             0.5
Lead, ppm                                0.1
Mercury, ppm                            0.01
Selenium, ppm                           0.05
Zinc, ppm                                25
Chromium, ppm                             1
Cobalt, ppm                               1
Nickel, ppm                               1
Vanadium, ppm                             1

Source: Adapted from McFarlane (1995).

TABLE 15-14
Pig Performance When Given the Traditionally Recommended Space of 8
Sq Ft/Pig or 7 Sq Ft/Pig (removal of 50% of the free space) or 6 Sq
Ft/Pig (removal of 100% of the free space).

                               SPACE/PIG, SQ FT

MEASURE                8           7           6        SE       (a)

Number of pigs         80          80          80       --       --
Number of pens         3           3           3        --       --
ADG, lb/d           1.54 (a)   1.50 (a)     1.32 (b)   0.02     <0.05
Gain: feed ratio    0.24       0.24         0.24       0.007     NS
Feed intake, lb/d   6.31 (a)   6.25 (a,b)   5.57 (b)   0.23     <0.05

(a,b) Means with a common superscript do not differ, P < .05.

Source: McGlone and Newby (1994).

TABLE 15-15
Floor Space Needs for Indoor-Housed Growing Pigs. For Partial
Slats, Add 10%. For Fully Bedded Barns, Add 50% to the Numbers in
This Table. Group Sizes of 40 to 100 Pigs/Pen Are Not Recommended.

                          SPACE NEEDS, [FT.sup.2]/PIG

PIGS, LB    TRADITIONAL     <20/PEN        20-40/PEN     100+/PEN (a)

5-30            2.5           2.5              2             1.8
30-75            4             4               3             2.8
75-150           6             6               5             4.8
150-250          8             8               7             6.5
250-350         na             9               8              7

(a) These requirements are speculative because they are obtained by
extrapolation. See recent studies at the University of Illinois by
Mike Ellis on group size effects on growing pig performance

Source: Hyun and Ellis (2001), Wolter et al. (2000), Wolter et
al. (2001), and Hyun et al. (1998).

TABLE 15-16
Recommended Space Needs for Pigs in Outdoor Lots.

                                  INSIDE AREA        OUTSIDE AREA
STAGE               WEIGHT, LB   [FT.sup.2]/PIG   [FT.sup.2]/PIG (a)

Nursery               18-75            4                   8
Growing-finishing     75-250           6                  15

(a) For some outdoor finishing pigs,50 pigs or less/
acre is recommended.

Source: Adapted from the Midwest Plan Service (MWPS-1).
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Title Annotation:Section IV Housing, Environment, and Nutrient Management
Publication:Pig Production, Biological Principles and Applications
Geographic Code:1USA
Date:Jan 1, 2003
Previous Article:Chapter 14 Production systems for adult pigs.
Next Article:Chapter 16 Waste and nutrient management.

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