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

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.