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Articles from 1999 In October


Wean-To-Finish Systems: An Overview

Wean-to-finish (W-F) has hit the pork industry by storm. The production system costs a little more to implement, but it's a lot less hassle.

Now producers want answers to questions about such things as utility costs and performance paybacks.

Birth Of A New System The introduction of W-F technology has led to production changes and new challenges.

Instead of designing nurseries for 6-8 groups/year and finishers for 2.7 turns annually, W-F units can handle 2.1 turns/year.

Instead of the traditional one nursery and two grow-finish barns, we now worry about matching W-F facilities at 2.1 turns/year with finishers at 2.7 turns/year and a whole host of other questions.

Why Wean-To-Finish? There are few tasks more detested than cleaning and disinfecting between groups of pigs. With all-in, all-out (AIAO), producers use high pressure washers to clean barns between pig groups to reduce risk of disease transfer. This is time consuming and messy.

Moving and mixing nursery pigs is stressful. Research suggests that even if pen integrity is maintained, each move through production costs a day of growth. Transporting pigs is costly. In three-site

production systems, moving pigs between nursery and finisher sites costs $1/pig or more.

All those drawbacks make W-F attractive.

In some cases, producers will absorb the slightly higher production costs of W-F in exchange for less power washing and pig moving.

A New Type Of Production The first reported W-F facilities were constructed in southeast Iowa by Oakville Feed and Grain. These facilities were traditional grow-finish units modified with partial woven wire flooring. Weaned pigs were held on the woven wire. Curtains were dropped to contain the heat in a smaller area of the facility. Later, the gates were removed and the pigs had access to both woven wire and concrete slat flooring.

Joe Connor, DVM, Carthage, IL, adapted the system by using a partial plastic nursery floor, the rest concrete slats. This adaptation is still used, but most producers use only concrete slats, with or without mats, for 1-3 weeks postweaning.

Challenges And Opportunities A major challenge of W-F systems is being an expert in nursery management for two weeks after placement, and then a grow-finish expert for the remaining 24 weeks. In larger systems, personnel are assigned the sole task of assisting during the critical two-week period after weaning.

An argument against W-F is the high cost of heating a facility in cold climates. Producers address this challenge by tightening up their facilities, restricting ventilation and using zone heating.

Many producers have adopted W-F because it simplifies pig flow and recordkeeping.

For performance, producers report daily gains of 1.4-1.45 lb./day with a feed:gain ratio of 2.6-2.7. Some report 1.5 lb./day gains and 2.4 feed conversions. These figures are remarkable when you consider 1997 PigChamp data suggests a national average of 1.34 lb./day gains and 2.9 feed:gain from 12.4 lb. to 243 lb.

University Of Nebraska Research There are no published research results comparing W-F performance to conventional nursery-to-finisher performance. The University of Nebraska is completing a trial sponsored by Alpharma Inc. and the National Pork Board that addresses some common questions asked by producers and their advisers.

This research is investigating the impact of three weaned pig management systems on performance from wean-to-slaughter weights. The systems under investigation include:

* Single-fill, W-F. Pigs are weaned into fully slotted finishing pens stocked at 7.5 sq. ft./pig from wean-to-slaughter.

* Double-stock (DS), W-F. Pigs are weaned into fully slotted finishing pens at twice the density of W-F (3.75 sq. ft./pig). Eight weeks after weaning, the pigs are divided into two groups, one group remaining in the original pen and the other moved to another pen in the same barn. Pigs are grown to slaughter at 7.5 sq. ft./pig.

* Nursery moved to finisher (NF). Pigs are weaned into a mechanically ventilated nursery with woven wire floors and stocked at 3.75 sq. ft./pig. Eight weeks after weaning, they are relocated to the same finisher as W-F and DS and grown to slaughter at 7.5 sq. ft./pig.

The university finishing facility used in this research is a 5-year-old, double wide, naturally ventilated, fully slotted facility with 8 x 14-ft. pens. The concrete slats are 7 in. wide with a 1-in. slot.

There are 15 pigs/pen for the W-F and NF treatments and 30 pigs/pen for the DS. There is a two-hole W-F feeder and one bowl drinker/15 pigs.

Heat lamps are used for supplemental heat for the W-F and DS treatments. Comfort mats were used in all trials. Pigs were floor fed three times/day for the first week after weaning. A commercial nursery diet was fed; diets were switched based on a feed budget.

Temperatures in the nursery were kept at 84-86 degrees F the week after weaning and were programmed to decline 3-4 degrees per week thereafter until 70 degrees F was reached. However, two of the three trials began in April and by mid-May outside air temperatures prevented the planned-for decline in temperature. Air temperature in the finishing facility was maintained at 73-76 degrees F with heat lamps used for supplemental heat as needed. They were generally removed after 3-4 weeks.

Pigs were weaned at 17 days of age and transported to the research unit at weaning. In trials 1 and 2, the pigs were purchased from a source 100 miles away. In trial 3, pigs were from a source 70 miles away. Trials were started in April and October in an attempt to pair up heating seasons and limit effects of season.

Two trials are completed and the third will be completed by the time readers receive this Blueprint.

In trials 1 and 2, veterinarians diagnosed gut edema 2-4 weeks postweaning. It was most severe in the W-F and DS treatments. In trial 1, only the W-F and DS treatments received medication. In trial 2, all pigs were medicated.

Pigs in trials 1 and 2 had many health challenges due to problems linked to Porcine Reproductive and Respiratory Syndrome (PRRS).

The reduction in performance for DS vs. W-F is probably related to group size. There is good evidence that increasing group size decreases daily feed intake and daily gain. However, the reduction in individual pig performance doesn't outweigh the overall improvement in pig weight gain per unit of floor space, a critical factor when assessing the economics of W-F strategies.

In spite of the health problems noted for trials 1 and 2 and the differential treatment of gut edema, W-F pigs outperformed DS and NF pigs during the nursery phase (Table 1). The response appears to be a feed intake response, resulting in faster daily gain, with no difference in feed conversion. Even though temperatures in our nursery were set low to reduce heat stress, feed intake was lower for the NF groups.

Table 2 offers a look at W-F PigChamp production data and nursery, grower and finisher performance.

Summary A lot of work remains for researchers. If we can determine why the increase in feed intake has been observed, it may be possible to apply that knowledge to conventional nurseries. It may be that W-F removes an unknown obstacle to feed intake that we have unconsciously built into many current production systems. It's clear from the results to date that the newly weaned pig can adapt to a variety of housing systems and perform well beyond our expectations. The challenge ahead is to resolve any obstacles to pig growth as housing technology evolves.

Health Management In W-F Systems

Wean-to-finish (W-F) is a technology that has become a common part of the hog industry. This technology truly breaks our paradigms of how pigs should be raised postweaning.

The most appealing part of this technology is that it eliminates two of the most disliked jobs in the industry, moving pigs and cleaning and disinfecting barns. Health in the first W-F barns was very good and has encouraged more adaptation of this production technology.

Some of the very first W-F barns were used in nursery partial depopulations. The question was raised whether performance was better due to the partial depopulation or to the W-F technology. Experiences were so good that producers decided to see if the performance could be repeated regularly in these barns.

The first attempts were made using standard finishing barns with minor changes to minimum ventilation, feeders, gating and additional, supplemental zone heating.

Redefining Production W-F fits very well into multiple site production. W-F optimizes multiple site production with only two sites in production - the breeding herd (gestation and farrowing) and W-F. This has provided a new definition for multi-site production. It is the only type of two-site production system that can be run all-in, all-out (AIAO) by site and is the most efficient multiple site type of operation that can be designed. There is only one transfer of pigs between the breeding herd site and the W-F site. Not only is the amount of movement reduced, cost is reduced because the pigs are smaller and more pigs can be transported in a single load or with a smaller trailer. However, sow herds must be very large to economically build these types of sites.

Health Kicks One of the health benefits of W-F may be that the pigs only have to be mixed with other pigs from other litters and/or farms when groups are formed at weaning. Different diseases may exist at a low level within the finishing group without being a problem because the pigs are never re-mixed.

This may be partly why some non-W-F, multiple site systems have more disease problems in finishing because groups are re-mixed as the pigs move to the finisher.

Health management in W-F is really much like conventional flow with a nursery and a finisher. The following factors must be weighed before making health recommendations:

* Health status of the source herd(s);

* The number of sources that will be delivered into the barn;

* The number of weeks of production that will be in the barn;

* Whether the site will be run AIAO by site; and

* Determining the ages of the youngest and oldest pigs.

Defining the herd health status of source herds is a continual process; to be successful, changes must be detected as soon as possible. A health monitoring program includes:

* Clinical examination and walk through;

* Postmortems;

* Diagnostic lab follow-up focusing on bacteriology, histopathology, virology, immunohistochemistry and PCR (Polyclonal chain reaction); and

* Serology of the sows and offspring looking at PCR on serum, slaughter surveillance and recordsreview.

Following a health monitoring program can help identify any change in health status of the sow herd. If herds are being commingled, it's even more urgent to continually monitor herd health status.

Fill Time The number of weeks to fill a barn and site depends on farm size. Ideally, barns would be filled on an AIAO-by-site basis in one week or less. No more than four weeks on a site and two weeks in a barn are fill-time compromises for smaller farms. These time parameters will help determine the dimensions needed for rooms and buildings.

Commingling is one way to help achieve the goal of filling sites on an AIAO-by-site basis. If a single farm can't flow enough pigs to fulfill the AIAO-by-site criteria, a compromise must be made with site size or number of sources. Smaller farms may be able to use batch flow to help increase the size of groups and be able to run these sites on an AIAO-by-site basis.

The number of herds that can be safely commingled is a tough call. Any time there is more than one source herd in a W-F barn, the potential for problems exists.

Matching health status of farms to be commingled is important. If the herd health history is similar, it will help reduce potential problems in commingling. Having the same or similar sources for breeding herd replacements helps to stabilize these herds.

If multiple herds are being commingled, it's a good idea to have a contingent pig flow plan in case the health status changes on one of the farms. Always try to lessen the number of herds needed to fill a given site.

Health Challenges Weaning age for many W-F systems is the same as conventional nursery systems; most are at 16-21 days. This makes the most of sow herd productivity. In this age range, pigs are easier to get started after weaning. This also helps reduce the cost of production and complexity of a diet to get good performance.

Minimizing the range of ages weaned into a barn is also crucial because of the immune status of the various age groups. This can result in more problems with Streptococcus suis, Haemophilus parasuis and Actinobacillus suis. By reducing the age spread into the barn, the immune status of the group is similar, reducing the chance for more problems.

The first health challenge is making sure the pigs get off to a good start. Keeping the pigs comfortable is the best way to ensure a good start and that the pigs stay healthy. A warm, dry and draft-free environment must be provided. Observing how the pigs are laying tells if the pigs are comfortable. Weaned pigs should lay next to each other but not be piled on top of each other. Some of the things to help improve pig care include:

* A clean, dry mat placed out of any potential drafts;

* Properly adjusted heat lamps (90-95 degrees F surface temperature); pigs should be lying comfortably under them;

* Provide feed both on the mat and in the feeder; and

* Make sure the pigs find the water source. Electrolytes (i.e., Bluelite, Orange Lyte, Restart) can also be used especially after long trips or in hot weather. By carrying out these procedures properly, the pigs are insured a healthy start.

Porcine Reproductive and Respiratory Syndrome (PRRS) can be controlled in a W-F system if the sow herd is stabilized and there is no shedding to the piglets. If the sow herd immunity breaks down, it can be a problem in W-F just as it would be in a conventional nursery/finisher system. Avoiding the move from nursery to finishing and re-mixing of pigs also reduces the chance of virus spread. Controlling Porcine Respiratory Disease Complex (PRDC) lessens PRRS problems.

PRDC has been a very big challenge in pigs 16-18 weeks of age. W-F can help control the various pathogens by not re-mixing pigs. This can help prevent the colonization of Mycoplasmal pneumonia that is normally seen as pigs move to the finishers. Many producers still vaccinate for mycoplasma because it has been such a problem in dealing with PRDC.

PRDC is controlled best in AIAO-by-site pig flow. The W-F barn becomes even more efficient if there is a very low prevalence of disease organisms and no re-mixing of pigs.

Diarrhea has been a bigger concern in W-F barns than in conventional nurseries. With concrete slats, it is easier to see diarrhea because there is more floor surface area than conventional nursery floors. This makes it seem like more of a problem. With more area exposed, there is more concern with build up of pathogens over time, especially in the more porous concrete.

There may be more problems in the future. One possible solution would be to use a concrete sealer if problems occur. Diet formulations may need to be looked at if scouring is a problem to make sure that nutrition is not part of the problem. Diarrhea is generally no more of a problem in W-F than in conventional nurseries.

Another advantage that W-F barns have is more square footage and total air space at the start of the growing phase. This makes it easier to maintain better air quality in the barn (lower humidity and gases because of less animal density). This may make it harder for organisms to spread by aerosol. Disease is a numbers game. If numbers can be reduced, the organism may reside in the herd but not cause disease.

Room temperatures are generally cooler in W-F barns. This is because more focus has been placed on zone heating due to the larger square footage and air space. This may be a health benefit in that it allows for more volume of air to be exchanged and improves air quality.

Therefore, ventilation rates can be cut dramatically, reducing the chance of drafts without sacrificing air quality. With lower temperatures and humidity, disease organisms have less chance to survive in the environment. This also reduces the opportunity for disease spread between pigs.

Transporting Pigs No Problem Transportation of weaned pigs still must be done with care but has been much easier than we thought. As learned in the multiple site production systems, the weaned pig is probably the easiest pig to move. They're very hardy and take the move quite well. Many systems have transported hundreds of thousands of pigs with less than 0.1% death loss. Some systems have hauled pigs up to 18 hours with no problems.

At first, the concern was more about transporting pigs in cold weather. But transportation in hot weather is as much, if not more, of a problem. This becomes a bigger concern if pigs come from more than one source and are hauled on the same trailer. It's important to be very organized at each stop to reduce loading time so the pigs already on the trailer don't become heat stressed. It's surprising how well these weaned pigs will load on truck or trailer with regular loading chutes.

When taking pigs out of the crates, take care not to put stress on the joints. Dislocated hips and knee joints can be a problem with careless handling. Supporting the pig's weight close to his body will prevent this type of injury from occurring. Make sure any chutes or ramps don't have openings that the pigs' small legs can get through and get caught. Gates and dividers must be close enough (no more than a 2-in. gap) to prevent pigs from mixing in the trailer, since most are sorted for sex at weaning.

Some farms tattoo pigs to identify their origin and age. This is key for commingling multiple farms. This allows for trace back of problem pigs and quality control back at the source farm. One method used is a six-digit tattoo. The first two letters/numbers are for the state identification, the next two identify the source farm and the last two identify the age. One letter/number is used for the week of the year, repeating every 26 weeks. The other is a number for the day of the week.

In most states, tattoos can serve as the premise identification if the state veterinarian's office has given prior approval. Some farms mark pigs under a certain age specification with a given color to ease sorting and managing. Entry weight is often specified and pigs under this given weight are transferred at a discount and identified (i.e., hole punch in the ear).

Pig Management Pig management after arrival is much the same as in a traditional nursery. Refer to other articles in this Blueprint for feed and water recommendations.

Loading pens: The pigs are penned according to size and sex. The number of pens left for treatment and recovery determines the number of pigs per pen. Having a split pen (a regular pen split in half to make two pens) available for a treatment pen and two recovery pens per 500 pigs works well.

Pen walking: Walk the pens daily, looking at every pig every day. It's most important pigs get started eating and have a full stomach. Those pigs not eating their fill will need to be sorted to the treatment pen where there is good quality feed available. This pen will be fed on the mat longer. Also, gruel feed will help some of these pigs that don't want to eat the dry feed. The quicker these pigs get back on dry feed the better.

The pigs that are having health problems and not competing will need to be sorted to the treatment pen for less competition and a better chance for complete recovery. Once the pigs have recovered in the treatment pen and are eating well, then move them to the recovery pen.

Treatment: Treatment protocols must be developed based on the farm's health history and sensitivity patterns. Pigs need to be treated daily as the pens are walked and examined for any signs of disease. Specifically look for gauntness (no fill in the belly), rapid breathing, coughing, lameness, sore toes, swollen joints and pigs that appear dizzy or off balance.

Time invested to make sure pigs get off to a good start can make the group easier to care for later on. Having plenty of help available during this time is vital. For large groups of pigs, extra staff can really help the group get off to a good start in the first 2-3 weeks.

Double Fill, Large Pens Double filling barns can produce health challenges. But double-loaded barns are a very efficient use of space in the early growing phase.

However, some of the W-F advantage is lost when half of the pigs are moved out to the finisher. Changes that may occur include the social order in the pen, the health status of the group and the opportunity for re-mixing organisms resulting in disease. It's still uncertain the impact this may have on a group.

If double loading a finisher, the best way to split the barn is to take half the pigs out and avoid re-mixing many of these pens. If the barn is filled with a barrow and gilt side, taking one side to another site and then splitting the pens in half will produce the least amount of re-mixing and still permit single sex barns or sites.

Large pen systems are gaining in popularity. This technology is useful for W-F systems also. One challenge is the ability to spot the sick pig and make sure that no one falls too far behind in the group. One advantage is pigs can find the most comfortable environment for them within the barn and room.

Cleaning and disinfecting is just as important in W-F systems. One good thing is that the barns have to be cleaned twice a year. One concern has been that concrete slats would be more of a problem because they can't be cleaned as easily as other common nursery floors. So far this hasn't been a problem even in retrofitted finishers.

Summary Health may be easier to manage in a W-F system. One big plus is no re-mixing of pigs and potential mixing of different health subpopulations within the group in the early growing phase.

Environment may be improved in the W-F barns because of the greater air space available and the focus on zone heating and comfort.

W-F isn't a silver bullet. We can have health concerns in these systems. But the technology does offer some unique advantages over conventional flow. W-F provides for improved pig flow with the pigs only having to be moved once from the farrowing site.

Equipment, Facility Designs

As with any production system, equipment selection and facility design are critical for success. Climate, pig flow, energy costs and other considerations must be factored in.

The most common wean-to-finish (W-F) designs are similar in building and pen configuration to our standard grower-finishers. Buildings are 40 ft. wide with two rows of 10-ft.-wide pens divided by a center walkway. Ventilation is usually sidewall or pit exhaust fans for cold and moderate weather and natural ventilation for warm/hot weather.

Typically, pens hold 25 pigs with a density of 7.5 sq. ft./pig for single stocking. For the past few years, facilities have used wider rooms for buildings of 50 ft. and 60 ft.

In an effort to further reduce cost per square foot, double wide (80-120 ft.) barns have also emerged. Along with wider rooms, larger pens of 75-250 pigs are common.

Actually, the 50-ft.- to 60-ft-wide rooms really call for larger pens to avoid narrow pen widths that could increase social stresses and reduce access to feed, water and resting/ sleeping zones. Experience and feedback from producers with these wider rooms and larger pen sizes is extremely positive.

Tight Facilities The first step in remodeling or building new W-F facilities is to reduce air leaks. This helps achieve proper air exchange rates and reduces ventilation heat loss.

The second challenge caused by large air leaks is poor air distribution and mixing. If too much air enters through leaks rather than the planned air inlets, air inlet velocity can't be maintained. This results in dead zones with poorer air quality and large temperature differences within a room.

Most facilities are curtain-sided, some using insulated curtains. A few units feature insulated stud walls instead of curtains.

Regardless of building type, focus on tight construction. A good sill seal, for example, is a must between the concrete stem wall and bottom sill plate. Curtains, if used, must be installed, adjusted and maintained to close tightly. Many facilities have tremendous leakage at the bottom of the curtain. This can be fixed by sandwiching the curtain between the sill plate and wood or polyethylene strips fastened with screws 6 in. on center, maximum.

In most weather, good curtain installation and maintenance can adequately reduce leaks. With extreme cold, windy weather or leaky barns, temporary use of heavy-duty plastic stapled on the inside of the curtain walls may be needed to reduce heat loss.

One of the first W-F buildings that I helped design the summer of 1996 was 60 ft. wide with insulated sidewalls. The producer used all mechanical ventilation with sidewall exhaust fans and ceiling air inlets for cold and moderate weather and tunnel ventilation for hot weather. For heat, we installed two-stage, overhead, radiant tube heaters over the center alleyway to heat the front area of each pen.

The heaters and the entire ventilation system are controlled by a multi-stage controller that can be adjusted at the room or from a remote office computer via a modem interface. The controller keeps a historical record of heater run time by room. This run time enables the producer to project propane use based on Btu input of the heater using 93,000 Btu/gal. of propane as a guide. The producer's estimated use of heating fuel was only 1 gal./pig through the winter, much less than curtain-sided, W-F buildings.

A tight facility, top management, 60-ft.-wide building and insulated walls helped achieve low fuel usage.

Some W-F buildings have used 100% natural ventilation with chimneys and, despite my pessimism, seem to be working fine. Precise natural ventilation does require a sophisticated control system including a relative humidity sensor to maintain adequate minimum ventilation. Of course, management and sound design are also a must.

Heating System Options One of the first concerns most producers have before trying W-F is keeping the weaned pigs warm enough. Their next concern is how to do it.

The answer is to use radiant zone type heat systems. Radiant heaters emit infrared rays like the sun. They don't heat the air directly, only the objects that the infrared waves strike. Warmed objects, slats, penning or pigs warm the air.

Because most W-F buildings are more prone to heat loss (not as well insulated) than typical nursery buildings, some type of radiant zone heat source (electric or gas) is often used. The objective is to reduce heat loss by zone heating the lying area and allowing the air temperature in the rest of the room to be 10-15 degrees lower. For instance, while the lying area temperature is kept at 85-90 degrees F, it may only be 70-75 degrees F in the dunging area.

Radiant zone heating does reduce energy costs over forced air heating. It is also one of the keys to improving pig performance.

Agricultural engineer Ron MacDonald, Guelph, Ontario, and I discovered the true benefit of radiant zone heating after a field study we coordinated during the winter of 1994-95. In a Midwest nursery facility, we compared performance of a zone heat system provided by two-stage, gas, overhead, radiant tube heat to that of forced-air, gas heat. We observed whether pigs chose to sleep close to or away from the radiant zone heater. Gas use declined, but most importantly, we recorded better pig performance. Death rate, feed conversion and especially daily gain were better for the radiant zone heat system.

With traditional, forced-air systems, we heat to meet the needs of the smallest and/or least healthy pigs in the room. Consequently, many pigs are either heat stressed or uncomfortable. They compensate by eating less to lower body heat production.

For heater design, first decide how big an area needs to be covered with radiant heat. Coverage area should be equal to the smallest lying area required. Of course, this depends on the size of the pig.

Unfortunately, the coverage area of radiant heat has been influenced more by the type of radiant heat source than actual pig needs. For example, a typical radiant heat lamp hung at 32-36 in. above the floor essentially covers an area of 7-10 sq. ft. (enough for about 20 pigs at 10 lb. or 12 pigs at 20 lb.). Of course, the amount of radiant energy received by the pig directly under the lamp will be much greater than the pig lying at 1.5 ft. from the center, depending on the type and size of bulb used. This allows pigs to arrange themselves under the lamp to meet their own needs. The problem is that many systems are only using one lamp per 25 pigs when they should have at least two lamps. With good pig health, some producers can get by with one lamp by raising the temperature setting 5-10 degrees so the forced-air heater runs more.

Economics dictates you can't afford to provide electric heat for very long because electricity is much more expensive than gas (Figure 1). For example, if electricity costs 8 cents/kwh, an equivalent heating fuel cost for propane would be $1.68/gal.

Common W-F Heating Systems There are three main types of heating systems being used in most W-F systems: electric heat lamps with forced-air gas heat, gas-fired radiant brooders with forced-air gas and radiant tube heat.

To cut heating costs, radiant heat should be used at least 2-6 weeks, based on the climate and season. For electric lamps, I suggest sizing for at least 20-lb. pigs (0.84 sq. ft./pig). For gas radiant heat (tubes or brooders), I suggest sizing for a 40- to 45-lb. pig (1.5 sq. ft./pig).

The heat lamp and gas brooder systems are operated similarly. The lamps or gas brooders provide a zone heat while traditional, forced-air gas heaters maintain room temperature at 70-75 degrees F for the first 5-6 weeks (until pigs are about 40 lb.). Depending on the controller, lamps can be operated, on/off, high/low/off or variable. Lamp usage is decreased as the pigs grow and turned off when pigs are old enough to sustain growth with a room temperature of 72-75 degrees F.

With brooders, target zone temperature is gradually reduced as the pigs grow. Some brooders cycle on and off while others are variable output. When the target radiant zone temperature is the same as the target room temperature, the brooders are turned off. After the lamps or brooders are turned off, the room temperature is adjusted as you would for grow-finish.

Facilities that use overhead, radiant tube heaters usually don't need a backup source of forced-air gas heat. Unlike most brooder systems which have a separate controller, tube heaters are controlled by multi-stage ventilation controllers. Producers like tube heaters because they only have to adjust one temperature controller for all the heating and ventilation equipment. Target temperature is reduced gradually as the pigs grow as you would in a typical nursery. Sensor location for zone heating systems is critical. For tube heaters the sensor must be located close to the radiant heat zone.

Heating System Costs There are two types of costs for heating systems: the initial equipment and installation costs and the operating costs for energy use and maintenance. Figure 2 compares these costs based on data collected from research at a site in central Illinois. The facility has four, 50-ft.-wide, 1,200-head rooms with insulated curtains.

Most producers do a good job of comparing the equipment costs but struggle with the true installation cost of each system. Although the cost of heat lamps is the least equipment cost, the system has the highest installation cost. Even though we projected heat lamps to operate only three weeks per turn, they still had the highest energy cost. This is because electricity is three to five times more expensive than gas.

Our current projections show that even though the lamp system has the lowest initial cost, the gas brooder system has a 1.9-year payback and the two-stage, overhead tube heat system would have only a 1.4-year payback for this Illinois facility.

Flooring The most common flooring is pre-cast, concrete slats. Also used are wire mesh, plastic and partial solid concrete. High quality concrete slotted flooring works well. If slats are not high quality, you're better off with partial plastic flooring for fewer feet and leg injuries.

Piglets quickly learn to walk on the tops of concrete slats. During the first few days, a leg might slip down into a slot, but with a wide enough opening the pig can pull his leg out without any problem. Slats should have no more than a 5-in. top; a 1-in. slot is preferred. Larger tops will result in messy pens. Slot edges should be even and smooth without rough protrusions. There is a wide variation in quality of concrete slats but many people can't spot the differences until it is too late.

Manure Handling Manure handling systems are the same as used in grow-finish. Most systems are either pull-plug, recharge pits with outside storage or below building deep pits. Manure volume varies with watering system and management but is generally about 75% of a grow-finish facility. This means that an 8-ft.-deep pit should provide one year of storage.

Remodeling Several clients are remodeling facilities to W-F. This is fairly straightforward for grow-finish buildings but complicated for other types of facilities. Evaluate each barn individually.

Even in a finisher there are many changes. Penning will likely need to be modified so pigs don't get trapped with wide bar spacing. Feeders and waterers must provide access for smaller pigs. Heating and ventilation are the largest changes. The building must be tight enough to provide the ventilation rate for small pigs. Smaller, minimum ventilation fans are needed. Some type of gas radiant heat should be added.

Large Groups Some producers have asked about special environmental challenges using big pens/large groups. There may be few if properly designed.

Ian Taylor, Animal Environment Specialists, Bloomingdale, IL, believes that with the hog industry's stocking densities and heavier finish weights, large group pens offer production advantages. He stresses the need for multiple feed and water stations within large pens to assure proper access and intake.

Also, the larger pen widths allow increased pig access to the radiant heat zone and greater choice of environment. These can be real shortcomings in traditional small group, narrow pen type buildings, particularly if double stocking is contemplated. Taylor suggests this increased flexibility expands the practical options available when remodeling or considering larger, more cost-effective buildings. He advises reviewing management, such as providing simple means for pig sorting. Taylor says that other management pluses are increased ease of walking through pens for inspection and the ability to re-mix recovered pigs back into the large group pens. Penning costs are certainly less. If there is a disadvantage to large pens, it is not with the facility design or equipment requirements.

Summary Economics will dictate. Improved pig performance and reduced labor are real advantages over three-site production. Facility cost is higher. We are still collecting data for the cost of heating these facilities.

Certainly, we will see more double-wide facilities as producers realize they can have tunnel-ventilated buildings for about the same cost as naturally ventilated. The only extra cost is to operate those big fans.

As we become comfortable with the concept of large pens, we will see an increasing number of 102-ft.- and 122-ft.-wide buildings. The days of the 40-ft.-wide finisher are numbered.

The New Economics Of Wean-To-Finish Production

Production and financial modeling is the best way to understand the economics of wean-to-finish (W-F) production. Using a model, we can compare the financial consequences of building a production system with W-F barns or standard nurseries and standard finishing barns.

In doing so, we found that W-F systems are here to stay because they are simple and they more than pay for themselves through lower production costs.

For this article, MBA 4.0 (our sophisticated software modeling program for hog production) is used to model a 20,000-sow, farrow-to-finish production system, built using either W-F buildings or conventional (multi-site) nursery and finisher buildings. Both scenarios take 409,085 weaned pigs from the sow operation per year.

The pig flow is based on a sow system with two, 10,000-sow sites flowing four-barn finishing sites all-in, all-out (AIAO). A fixed weaned pig cost of $34.50 was used. A W-F production system of this size would be built using 52 sites with four, 960-head finishing buildings per site, 208 buildings total. A standard nursery-finisher system would be built using 68 sites, one site per nursery building (32 nursery buildings with each nursery holding 2,000 head); 36 finishing sites, four, 960-head finishing buildings per site (144 finishing buildings).

The W-F units run a 26-week, fixed-time flow. The nursery is an eight-week, fixed-time flow. The standard finishers run an 18-week, fixed-time flow (26 weeks total, just like the W-F system).

Kansas State University's (KSU) swine nutritionist Steve Dritz's numbers were used. The KSU veterinarian outlined these W-F performance advantages: 1. A 7- to 20-lb. improvement in ending weight at the same age (3- to 7-lb. increase from less down time and 7- to 15-lb. increase from feed intake-daily gain improvement);

2. No advantage in feed efficiency;

3. No advantage in carcass value and lean premium; and

4. About a 50% reduction in mortality and culls for the W-F building. In the same 26-week, fixed-time schedule, it means that the average weight out of the W-F system is 270 lb. vs. 255 lb. for the conventional nursery-finisher system.

Other production and financial assumptions:

1. Mortality for the nursery-finisher system at 5.5% total and W-F at 3.0% total;

2. Equal feed conversions between the two systems (about 2.65);

3. Equal lean value premium for the two systems ($4 per head);

4. Allocated one full-time employee (1 FTE) for every two nursery sites; and

5. Feed cost/ton is essentially the same for the two scenarios.

The differences in building costs reflect current costs in the Midwest for W-F, nursery and standard finisher buildings.

On per-pig costs going into the model, the electricity cost was slightly higher per pig for the conventional nursery-finisher; the propane cost was higher for the W-F buildings; insurance, property taxes, repairs and maintenance, waste management, transport, animal health, miscellaneous and management fees were all higher for the nursery-finisher system. Depreciation and interest expenses were higher for W-F.

The two production systems were run side-by-side for 10 years, paying off all debt by the end of year 10, leaving the owner with 100% equity in the business. The financial results speak for themselves.

Over 10 years, the W-F system produced more than 10 times the total profit of a standard nursery-finishing system. By building a W-F system, you would make $9.67 more before-tax profit per head sold. Over 10 years, you would have over $38 million more before-tax profit or $27 million before-tax free cash flow (profit plus depreciation less all principal payments).

You may have heard people say that you can't produce as many pounds per square foot in a W-F system. As you can see from our results, that's correct.

But it doesn't matter because the profit per square foot is so heavily tilted to the W-F system. If the total pounds of pork produced annually were equal between the two systems, then pounds per square foot might be a key decision-making number.

However, in our analysis, the W-F system still wins because of lower costs (yes, even accounting for higher building costs). W-F production systems have lower transportation costs, lower animal health costs, lower water costs and lower waste management costs.

And if you figure a management contract cost, they are lower on this, too. (We're assuming no cash difference in labor costs, although you can use labor more efficiently in a W-F system. "No cash difference" means that even though you save a lot of labor in moving pigs and power washing/clean-up time, you still can't really reduce your workforce.)

The same logic holds for asset turnover ratio. It's higher in a standard nursery-finishing system but who cares when you're making almost $10 more per pig sold (Table 2).

These apparent contradictions - pounds per square foot and asset turnover advantages to a standard nursery-finisher system - show that you just can't rely on one number in evaluating the profitability and financial efficiency of a project. You have to look at the total picture. Profit margin per pig sold is the driver.

We'd be happy to run the model with equal costs or even give all cost advantage to the nursery and see what happens. But even before we did it, we could with confidence say - at least according to our models - the performance advantages to a W-F system will blow away the cost advantages, even if we gave every cost advantage possible to the nursery-finisher system.

There's a reason W-F buildings are here to stay and it's simple: You make more money using them.

Wean-To-Finish Nutrition

Nutrition and feeding management of pigs in wean-to-finish (W-F) systems have received little attention in trade publications and research programs. Generally, producers have adapted nursery feeding strategies for pigs early in the W-F cycle and finishing feeding strategies for pigs late in the W-F cycle.

The concepts involved in developing a sound nutritional program and delivering it effectively and efficiently are similar for both W-F and traditional, nursery/finish production systems. However, there are subtle but important differences, particularly in feeding management, that need to be taken into account in order to maximize profitability.

First, the nutritional needs of the animals during each phase of production must be determined. Second, diets must be formulated to meet those nutritional needs at the lowest possible cost. Third, feeding management must allow the delivery of the feed to the animals in a manner that maximizes production performance and minimizes waste.

Determining Nutritional Needs There is no published evidence that nutrient needs of newly weaned pigs in W-F systems are different than those of pigs weaned to a traditional nursery. Pre-starter and starter diets that work well in a nursery should also work well in W-F facilities. There is evidence, however, that early mortality rates are lower in W-F systems than in nurseries, suggesting that pigs in W-F facilities are healthier. The literature contains compelling evidence that the nutrient and ingredient needs of weaned pigs are affected by the level of immune activation. If weaned pigs in a W-F system have a lower level of immune activation relative to contemporary pigs in a nursery, it may be possible to feed less complex, cheaper nursery diets without having a negative impact on growth.

A logical approach to fine-tuning nutritional accuracy and reducing feed cost of newly weaned pigs in a W-F system is to start with a proven starter program. The next step is to systematically reduce the nutritional complexity of the diets by formulating lower levels of plasma, milk products and highly digestible protein sources, and higher levels of corn and soybean meal, while monitoring animal performance. Producers who don't have the ability to alter diet composition can conduct a similar analysis by altering the amount of each diet fed and monitoring performance. It may be possible to make diet changes earlier in W-F systems, feeding less of the more expensive diets, without reducing performance.

Our experience has shown that pigs in a W-F system will reach market weight 7-10 days faster than similar pigs in a traditional nursery/finish system, with similar carcass composition at slaughter. This suggests that the shape and/or slope of the lean growth curve is different for W-F than for nursery/finish systems. Figure 1 shows the shape of a typical lean growth curve for W-F vs. a typical lean growth curve for nursery/finish. It is clear that the main difference in these two growth curves occurs during the accelerating phase of lean growth, from 40-100 lb. The reason for the differences in the shapes of the lean growth curves for the two systems hasn't been determined.

However, one can postulate that space limitations late in the nursery, and stress caused by transportation and acclimation to new facility and social environments, cause a deviation in the normal growth curve for pigs in nursery/finish systems. Since pigs in the W-F system experience little stress, their lean growth curve doesn't dip in the 40- to 100-lb. phase.

Feed intake pattern is also different for W-F than nursery/finish during this 40- to 100-lb. phase, with pigs in W-F consuming more feed. Producers with both W-F and nursery/finish systems, or those contemplating switching from nursery/finish to W-F, need to develop lean growth and feed intake curves for both systems to accurately determine nutrient needs.

Determining the nutritional needs of W-F pigs over 100 lb. is similar to determining the nutritional needs of pigs in a traditional finishing system. Nutrient needs are determined by assessing feed intake and the lean growth potential of both barrows and gilts during each phase of production. National Hog Farmer Blueprint Series No. 27, Understanding Lean Growth, Oct. 15, 1998, covers in detail the process of establishing lean growth curves, feed intake curves and using this information to develop a feeding program.

Diet Formulation Diet formulation involves taking the nutrient requirements (and ingredient requirements for pigs from weaning to 30 lb.), the available ingredients and their costs, and using a least-cost formulation program to develop diets that meet or exceed requirements at lowest cost. This process is similar for W-F and nursery/finish systems.

However, as mentioned above, nutrient and ingredient needs of pigs in W-F systems may be different than those of pigs in nursery/finish systems, resulting in the need to formulate diets specific to each production system.

Feeding Management Proper feeding management is critical to top W-F performance. In addition, feeding management is substantially different for W-F and traditional nursery/finish systems.

Select a feeder for W-F that allows ready access for weaned pigs and sufficient head space for large finishing hogs. The ideal W-F feeder is a dry feeder with solid dividers. Trough lip height should be low, no more than 4.5 in. high, so that small pigs can easily access the feed. If a feeder without solid dividers is used, it's important to use feeder inserts that prevent pigs from lying in and getting stuck in the feeders.

Wet-dry feeders aren't recommended but can be used with the water shut off to the feeder and another source of water. If the water to the feeder is not disconnected, feed spoilage will occur during the first few weeks when feed intake is low. Pre-starter spoilage is both costly and detrimental to feed intake. Water to the wet-dry feeders can be reconnected when the pigs exceed 30 lb.

Tube feeders aren't ideal for W-F use but can also be made to work. One disadvantage is difficulty in filling them by hand, a common process in W-F feeding management.

Water intake is critical to early feed intake. Cup waterers, particularly those with a drip screw, work best for W-F because there is residual water in the cup to attract pigs to water. If nipple waterers are used, allow them to drip for the first few days to attract pigs to water. Failure to do so can result in increased levels of navel sucking and fall-behind pigs. Install a nipple that can be operated by small pigs. Don't use finishing nipples for small pigs. It may restrict access to water, reducing performance. Provide one water cup per 15 pigs. Place waterers close to feeders.

Ideally, W-F barns will be set up with two feed storage and handling systems. One system can be a conventional bin, auger system common to finishing barns. This system should be designed for separate sex feeding. The second system consists of a smaller bin for pre-starter feed. Without a separate feed system for pre-starter, it's necessary to handle pre-starter in bags to ensure that the proper amount of fresh feed is fed to each pen of pigs and that there is no contamination with finishing feed from the previous group. Store bagged feed in a clean, dry area.

Hand feeding newly weaned pigs on a feed mat is an important way to maximize feed intake and early growth performance and reduce the number of fall-behind pigs. Pigs should be fed at least four times per day on feed mats until they are eating well, which typically occurs at 7-10 days postweaning. Allow 30 sq. in. of mat space per pig. Mats should be rubber or plastic with a lip height of at least 1/2 in. to reduce feed wastage. Avoid using plywood because it's difficult to clean thoroughly. Rubber mats are preferred because they stay in place better than plastic mats. Place mats near the feeders and within the zone heating areas.

Multiple feedings of small quantities is recommended to keep the feed fresh. A good rule of thumb is to provide one-half the pig's daily intake on the mats, keeping the pigs just hungry enough to seek out feed from the feeders. Weaned pigs will typically eat 0.5-0.6 lb./day. Six feedings of 0.05 lb./pig spread throughout the day will meet the objectives of encouraging feed intake and teaching the pigs to seek out, and eat from, the feeders.

Consistent, accurate feeding is most easily done using a scoop that delivers the right quantity of feed based on the number of pigs in the pen. Feed fines and rejected feed should be dumped off the mats before adding more feed. When pigs start to mess the mats repeatedly, remove them from the pens.

Managing 'At-Risk' Pigs It seems that every group of weaned pigs contains "at-risk" animals. That category includes early weaned pigs, pigs with low weaning weights, fall-behind pigs and pigs showing signs of disease. At-risk pigs need to be housed in the warmest section of the barn, near the center on the south side. They shouldn't share a feeder with pigs that aren't at risk because their feed changes need to be staged differently than other pigs in the barn.

Besides mat feeding, at-risk pigs do best if they are gruel-fed. Often, producers are tempted to treat at-risk pigs, when what they really need is nutrition. Gruel feeding is the most effective method of encouraging small, at-risk pigs to consume feed. Gruel (Figure 2) should be mixed fresh for each feeding and fed at least three times per day for the first 5-7 days postweaning. Provide just enough gruel that it can be consumed in no more than 15 minutes. Continue mat feeding while the pigs are being gruel fed.

One technique that works well is to gruel feed first thing in the morning, at noon and last thing in the day, with two to four mat feedings interspersed between gruel feedings. Reduce the quantity of feed put on the mats when gruel feeding to prevent feed waste.

Also, at-risk pigs need to stay on pre-starter 7-10 days longer than normal pigs. Save 4-5 lb. per pig in bags or the cart bin to feed to the at- risk pigs after the other pigs have switched from pre-starter to the first starter feed. When subsequent feed changes are made, filling the feeders of at-risk and fall-behind groups prior to delivery of the new feed will allow these groups to stay on the more nutrient-dense diets longer. This technique can help prevent the small pigs in each group from falling further behind the rest of the group.

Feed Budgeting The feed budgeting process for W-F systems is akin to standard nursery/finish systems. Figure 3 shows an example of a W-F feed budget. The budget should contain eight diets, four diets from weaning to 50 lb. and four diets from 50 lb. to market. Many producers use 10- to 12-step feeding programs in W-F systems in an effort to fine-tune output and reduce cost.

Regardless of the number of diets used, the feed budgeting process is an important step in making sure the right feed is in front of the pigs at all times. Preferably, feed budgets should be based on the quantity of each feed delivered, but can alternatively be based on days on each diet. Separate feed budgets should be developed for barrows and gilts.

Feed bin management takes on added importance in W-F systems. Between groups, it's critical all finishing feed from the previous group has been removed from the bin and that any mold or feed buildup is cleaned out prior to the delivery of starter feeds. Power washing the bin with hot water followed by disinfectant and adequate downtime for complete drying is recommended. In cold climates, all bins should be thoroughly cleaned prior to freeze up.

When changing from one diet to the next, bin inventories must be drawn down before adding the next feed in the sequence to ensure the right feed is in front of the pigs at all times. In addition, bins should be completely emptied at least once a month. This step is key to preventing the contamination of late finishing feed with nursery feed that potentially contains medications with extended withdrawals.

Split-sex feeding has been shown to improve performance and reduce cost in finishing pigs and now is a routine practice in most operations. It's equally important in W-F systems. At arrival, gilts and barrows should be penned and fed by separate feeding systems.

Invariably, there are either more gilts than barrows or more barrows than gilts. If there are more gilts than barrows, the largest gilts should be penned with the barrows. Conversely, if there are more barrows than gilts, the smallest barrows should be penned with the gilts. This method allows all pigs to receive diets that most closely match their nutritional needs.

Conclusions W-F is an exciting new production scheme. An integral part is learning how to properly feed these pigs. Much is known, but we need to learn more about the lean growth patterns of W-F pigs and their resulting nutrient needs.

Breeding Herd Down 8% From Last Year

USDA reported market herd and total herd numbers came in close to trade expectations, but the breeding herd was about 2% below average estimates.

According to USDA's Sept. 1, Hogs & Pigs Report, the breeding herd was estimated at 92% of levels shown one year earlier. Both the market herd and total herd were estimated at 96% of the previous year.

Our gilt slaughter data would indicate a slightly smaller breeding herd, although that data is biased towards the Corn Belt. Corn Belt states' breeding herd was down nearly 12%.

Breeding herd estimates in Illinois and Wisconsin were down 20% or more. Herds in Indiana, Iowa, Kansas, Nebraska and Ohio were down 10% or more. Missouri, Minnesota and South Dakota showed decreases less than 10%.

Arkansas, Georgia, Kentucky, North Carolina and Pennsylvania averaged 1% less in the breeding herd. Oklahoma's breeding herd was estimated to be up 10% from last year.

USDA shows the 33 states that do not have individual state data for Sept. 1 are down about 5% in their breeding herd. Based on National Pork Board marketings from these states in 1998 compared to 1997, we believe there is a chance that USDA is overestimating these states' production. However, it would take quite a large miss in these states to influence the total U.S.

Conditions in the hog industry continue to be favorable for concentration in production and vertical coordination with packing. When the purchase of Murphy Family Farms by Smithfield is completed, we believe about 25% of the U.S. hog industry will be vertically integrated. We believe that another 45% of the industry is now vertically coordinated - meaning the hogs are under marketing contracts with packers.

Based on the heavier-weight-market-hog inventories and the 10-year slaughter relationship with these inventories, this year's fourth quarter slaughter numbers could be down almost 7%.

However, using last year's fourth quarter slaughter numbers relative to the heavier-market-weight inventories, this year's fourth quarter slaughter numbers would be down only 4%.

There is a tendency for slaughter numbers to be lower relative to the heavier-market-weight inventories in years when production is declining. Therefore, we estimate a slaughter reduction of about 6% for October, November and compared to 1998.

Based on the 10-year relationship between the under 60-lb. market inventories on Sept. 1 and slaughter in the first quarter of the following year, hog slaughter in January, February and March should be down a little more than 8% from a year earlier.

However, using last year's relationship of marketings in this quarter and the lighter-weight inventories, slaughter would only be down a little more than 4%. For this quarter we are going to go with slaughter down a little more than 6%. Again, marketings in the first quarter have been lower relative to the September inventories in years where production was declining.

Productivity growth continues, a situation where what is good for the individual producer is not desirable for the total production segment of the industry.

Although the breeding herd on June 1 was down 6%, farrowings during June, July and August were down only 4%, and the pig crop was only down 3%. With a breeding herd down 8% on Sept. 1, farrowing intentions for September, October and November are forecasted to be down only 5%. December, January and February farrowing intentions are forecasted to only be down 3%.

We are hoping that both quarters' farrowings will be a little below the intentions. If so, marketings in the second and third quarters will be below our estimates in Table 2, which would be positive for prices.

Demand for pork at the consumer level continues to show a 1-2% growth for January-July compared to last year. This is the fourth consecutive year with some growth at the consumer level.

Our slaughter estimates and prices by quarter for the next 12 months are in Table 2.