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Focus on depop and repop

Dr Pieter Vervoort and Dr Anni Labuscagne, Charles Street Vet-group
A relative new buzzword in the pig industry is depop/repop.  Most pig farmers know of a pig farmer who is busy going through the pains of depop/ repop.  But what exactly is meant by it and is it really worth one’s while? In this article the difference between different strategies will be discussed and then a closer look will be taken at total depopulation/repopulation.What is the difference between different approaches?
Total depopulation/repopulation
This is the most expensive method but also the one that is most likely to succeed.
Over a period of time all the pigs are removed from a farm and once the farm is free of pigs cleaning starts.  No stone is left unturned in an attempt to clean and disinfect everything on the farm.
Washing and disinfection must be done at least three times with a week between each session.  For disinfection to be effective, it should be left to dry completely (this can be extremely difficult in the rainy season!) Although it is not necessary, many farmers rebuild some buildings and renovate others.  With no pigs on the farm wear and tear becomes clearly visible and it is a golden opportunity to give the farm a face-lift.
During a depop/repop many farmers take the opportunity to modernise and expand their operation.
Partial depopulation/repopulation
This method is less expensive than a total depop/repop, but the possibility of disease breaks is bigger. You will also consider this method if you have valuable genetic material that you want to save.
All the grower animals and young gilts are marketed or removed to another farm.  The only animals staying are the sows from second parity onwards and the boars.
The reason for this is that you want animals with a stable immunity on the farm.  Once all the growers are gone you start treating the remaining animals for three weeks with an antibiotic against various bacterial diseases.  17 weeks before all the growers are gone you must stop inseminating the sows as a break in farrowing is advised for greater success.
As the farm empties you start cleaning and disinfecting in the same way as for a total depop/repop.
Once the sows start farrowing they are moved into clean crates.  New gilts and boars are only bought from “clean” sources.
A partial depop/repop is only effective where bacterial diseases are a problem, but it is not the method of choice if viral diseases are a problem.

Total depopulation/repopulation

Reasons for depopulation/repopulation

There are many reasons why a farmer decides to “start again”, but the main ones are: Improved production of the sow herd but especially of the growing herd; repopulation with improved genetics; to obtain a disease-free status with the associated cost savings.

Which diseases are eradicated?

APP, enzootic pneumonia, atrophic rhinitis, S. suis, pasteurella, mange and internal parasites.
How much medication is used after a total depop/repop?
One of the added advantages of having disease free stock is that your medication bill will drop by a significant amount.
Although the herd may still not be medication-free, only a fraction of that used in the past will be needed.  The weaners may need some medication to prevent E.coli and the growers may need some medication to control some enteric diseases.
No medication is generally administered the sows, but it stands to reason that sore feet, abscesses and other minor problems will still be treated with the appropriate drugs.
Vaccination of sows for Erysipelas, Pavo/lepto and E.coli is also advised, but the growers are not vaccinated (after a depop/repop you should be rid of the various respiratory diseases.)
What will be the production lost?
Depending on whether off-site breeding is performed or another farm is rented this time varies.  Some indication is given below:

  • Continuous flow farrow to finish – no offsite breeding: 46 weeks production lost
  • CF farrow to finish – with offsite breeding:  36 weeks production lost
  • 2 site- with offsite breeding: 18 weeks production lost
  • 3 site- with offsite breeding: 10 week production lost
  • Rental:  0 – 6 weeks production lost.
  • The benefit of offside breeding lies in the fact that is saves 16 weeks of down-time.
  • AI makes it very possible and it works for a weekly or a three weekly system.
  • What are the costs involved?

What is your return on investment? Using the above figures you should have your total investment returned within 11months.
Depop/repop is probably not the answer for everyone. It must be seen as an alternative strategy to make your pork production facility more profitable. The technology is now well understood and the pros and cons well proven.
The benefits should be fairly easy to quantify in each individual case. Enough experience has so far been gained in South Africa to make the decision making process easier for those now contemplating the application of this technology. Each pork producer, with the help of his consultant, should be able to ascertain whether he should further investigate the relevance of this technology to his enterprise.

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