Purdue Pork Page Archive
The concept of SEW and the rules to make it work
SEW CONCEPT
Segregated early weaning is a term used to describe a management technology for producing high health status pigs from sow herds endemically infected with a multitude of disease agents. Vaccines and antibiotics are used strategically to aid the control or elimination of some diseases. The operational theories behind the success of SEW technology are not new, but are used in combination such that producing high health status pigs is consistent and predictable. For ease of understanding, the components of the technology are separately described below.
Weaning age -- Pigs weaned from their dams at less than 21 days benefit from high concentrations of colostral antibodies and are usually protected from colonization of infectious agents carried by their dams. Weaning ages and strategice use of vaccines and antibiotics vary for the control of transmission of specific diseases.
Biosecurity - Cleaning, disinfection, and other biosecurity measures are required to prevent disease agents present in the environment from being transmitted to growing pigs.
Segregation - Rearing batches of pigs (usually no more than a 7 day age variation) all-in, all out by room, building, or site is required. Facilities with the best segregation usually result in pigs with the highest health status.
Weaning age rules
Rule 1. Bacterial transfer
Bacterial transfer from sows to pigs can be controlled by weaning age
a) Except for S. suis and H. parasuis
b) weaning age less than 14 days will eliminate most bacteria
--Varies with pathogen
--Varies among pigs in litters, litters, and herds (passive antibody status)
Rule 2. Virus transfer
Virus transfer from sows to pigs is not influenced by weaning age
Equalizing immune status among sows most important
This can be done by exposure or vaccination
Rule 3. Cross fostering
Cross fostering may enhance sow to pig transfer of pathogens
Don not cross foster after pigs are 24 hours old
Cross fostering age may vary from herd to herd
Biosecurity
The major source of new diseases for the breeding herd comes from purchased animals. Thus, the rules for breeding herd additions will be listed first in this section. The sources of disease agents to growing pigs are related to moving groups of pigs from farrowing to nursery and then to finishing as each subsequent environment must be free of potential pathogens that might infect the high health status pigs produced by early weaning. The following is a list of some, but probably not all, biosecurity measures required to raise high health status pigs.
Rule 1. Placement
Isolation facility must be at least 300 yards east of breeding herd
Isolation facility must have a 60 day capacity
Rule 2. Disease matching
Incoming stock must not have diseases new to the herd
--Test results
--Vet to vet conference
Incoming stock must be exposed to or vaccinated for diseases of the recipient herd
Rule 3. Preparation of gestating sows
Viral infections--PRRSV, PRV, SIV, TGE?
--Keep sows vaccinated when these diseases are endemic in the herd
Bacterial infections
--Vaccinate sows as needed
--May need to vaccinate sows for M. hyopneumoniae
Rule 4. Cleaning
All rooms that hold a batch of pigs must be cleaned with a high pressure washer
Cleaning includes all equipment
Rule 5. Disinfection
All rooms and equipment need to be disinfected
Disinfectant to be determined with veterinary input
Rule 6. Down time
After disinfection, rooms need to be left empty for drying and organism killing
Down time varies dependent on diseases present
Rule 7. Work sequence
When multi-aged pigs are at one site always work from youngest to oldest pigs
Never go back without clean boots, coveralls, and washing of hands
Rule 8. Rodents
Before adding a new batch of pigs, check for rodents
Repair rodent barriers
Hire professional exterminator to eliminate rodents
Rule 9. Worker cleanliness
Workers must start the day with clean boots and coveralls
Workers exposed to older pigs (adults or finishers) should shower before entering nursery
Rule 10. Building sites
SEW nurseries must be placed 300 yards upwind (west) of a breeding and finishing facilities
Greater distances increase security
Rule 11. Vehicles
Vehicles from outside the premises must be cleaned and disinfected before entry
Rule 12. Dead animals
Dead animals must be placed outside the premises for pick up
Rule 13. Load out
Load out facilities must be placed at the perimeter of the premises
Rule 14. Visitors
Visitors should be minimized
Visitors must follow rule 9 before being allowed to enter facilities
Rule 15. Perimeter security
A fence around the perimeter of the facilities is preferred
If site is isolate, the perimeter fence may not be needed
Rule 16. General
If a biosecurity issue has no rule, be conservative on rule development
Segregation
The best case pig segregation scenario would be to place each batch of weaned pigs (no more than 7 day age variation) in a room, building, and site separate from all other pigs. In addition to this separation, the best herd size would be 4000 to 5000 sows such that 1600 to 2000 pigs would be placed in the building/s by sex for phase and sex feeding. Obviously, except for a very small group of producers, these conditions would be impossible to emulate. Nonetheless, nearly all producers, no matter what their herd size or current facilities configuration, can take advantage of this new technology after some thought and planning.
The minimal change towards segregated rearing would be to separate age groups of pigs by room in existing facilities (all-in, all-out production). A more advanced step would be to build an off-site nursery that would accommodate 7 or 8 weekly groups of pigs in rooms off a common hallway. These pigs could be sold as feeder pigs or returned to all-in, all-out finishing units. From these 2 scenarios to the most advanced system described above are about as many segregation possibilities as there are producers to create them. These possibilities also can be expanded to accommodate production networking. No matter what system of SEW technology is used by a producer, pig performance will generally be enhanced. Additionally, the more the segregation mimics the best case scenario described above, the nearer producers can come to attaining the genetic growth potential of their pigs.
Segregation rules
Rule 1. Placement of batches
By room--least biosecure
By building--reasonably biosecure
By site--most biosecure
Rule 2. Age range of batches
Three days (twice a week weaning) is best
Seven days is common
Fourteen days is risky, but has worked
Rule 3. By herd vs by age
One batch from 1 herd at 1 site--best
Multiple ages from 1 herd at 1 site--OK
One age from multiple herds at 1 site--OK (Herds must be of equal health status)
Rule 4. All-in/all-out management
All batches of pigs are to be moved all-in/all-out (no exceptions)
Rooms, buildings or sites can be filled over time (10 day maximum) as long as maximum weaning ages are maintained
Only at slaughter can groups of smaller pigs be moved back with younger pigs
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