1. External measures to prevent entering of pathogens.

   • Location of the farm: should be far enough from other farms, esp. in the direction of the dominant wind. Some infectious particles can spread through the air or by flies over short distances. Also rodents can spread some diseases from one farm to another.(This is called "constitutional biosecurity).
     
     

   • Purchasing policy: on the breeding farm, purchasing should be minimised and carefully selected on sanitary status and vaccination. In fattening farms, purchasing sources should be minimised.
     
     

   • Quarantine: when new animals are brought on the farm, they should be kept in quarantine for veterinary observation. In many European countries, this is a legal obligation. Practically, this period is 4 to 6 weeks. When a fattening farm is ran on a strict "all in all out" base, the whole cycle can be seen as a quarantine.
     
     

   • Visitors: should be minimised. Before entering the farm, they should put on an overall and boots that remain on the farm. They should also wash and disinfect their hands !
     
     

   • Vehicles: trucks transporting animals should be thoroughly cleaned and disinfected between every transport to prevent cross-contamination. The rule is : first clean, then disinfect. For cleaning, a slightly alkaline detergent should be used (alkaline products remove organic dirt like fats and certain proteins; acids remove inorganic dirt like lime scale). However, if the product is too alkaline, or contains sodium hydroxide or chlorine, it will corrode the body of the truck, especially the aluminium parts. In other words, a SPECIAL product should be used (such as HATCHONET ™, free of sodium hydroxide and chlorine, but rich in surfactants or wetting agents that will decrease the surface tension and break through the dirt). If only water with high pressure is used, it won't be possible to remove these specific types of dirt. Non disinfected trucks should not enter the farm for pick up. Also the rims should be disinfected. The vehicle disinfectant should obviously be non corrosive (in other words : it should have a neutral pH, like VIROCID ®).
     
     

   • Footbaths: at the entrance of every house, a footbath should be installed. First, the boots should be cleaned and only then dipped in the foot dip. The disinfectant should have a broad spectrum to kill ALL micro-organisms, even in presence of organic material, and should keep it's activities at low temperatures (check if it has been tested at 4° C or 40 ° F ) and at all pH values (which is not the case with chlorine, for example) . Ideally, it should be renewed daily. The whole design and construction of the farms is called "structural biosecurity" and should allow to clean easily (no hidden corners nor difficult to reach places).

   
   
2. Internal measures to prevent development and transmission of pathogens within the farm

   • Cleaning and disinfection: after every cycle, cleaning, disinfection and sanitary stops are essential. A long sanitary stop or "downtime" will never kill the eggs of Ascaris, Isospora nor Eimeria (coccidiosis), nor will it eliminate Rota virusses nor bacteria that cause Dysenteria. So, disinfection is a must.

Hygiene consists of two parts : CLEANING and DISINFECTION.

Disinfection without cleaning first is a waste of money. Cleaning is the management of dirt that can be seen partially: to separate and remove this dirt from a surface, through water and a detergent. In other words : to make the surface as free as possible from organic soil, that would impede the disinfectant to reach the surface.

Therefore, the characteristics of a detergent are explained in table 1 :

Table 1: Characteristics of Detergents
Wettening:	Decrease surface tension
Dispersing:	Split up dirt particles
Emulsifying:	Float oil and fat
Suspending:	Float dirt particles
Carrying:	Of dirt to the sewage
Sequestring:	Dissolve salts

Four factors will determine the functioning of a detergent :

1. Chemical energy : pH and concentration. (Alkaline detergents remove proteins and fat; acid detergents remove mineral deposits like scale)

2. Thermal energy (Fat starts to dissolve as from 35 ° C or 95 ° F)

3. Physical energy (eg. a high pressure washer, manual scrubbing or "elbow grease", …)

4. CONTACTTIME : this will enable the chemical energy to do it's job. Moreover, it's the only factor that does not cost any energy, its Free Of Charge !

Therefore, often FOAM is used in stead of a "classical detergent", since it adheres longer. But today, a new generation of cleaners has been developed in the form of GEL (BIOGEL ™). Increasing the contact time will allow to save on water consumption, labour and energy, as shown in fig. 1 :

The gel application does not require any "elbow grease" and hence saves a lot of labour.

A good cleaning job should allow for an 80 % reduction of micro-organisms, generally known as a "sanitised" situation. This will allow the disinfectant to reduce the rest of the pathogens easier.

What are the criteria for a good disinfectant?

• Composition: how many groups of disinfectants are combined within the product? And : is there a synergy between the different groups? As an example, quaternary ammonia compounds or QAC will work in synergy with aldehydes and significantly increase the efficacy. The QAC will allow the aldehyde to penetrate better in order to do their work (kill) in every crack , pore or microscopic hole. The QAC alone would not kill naked viruses nor spore bacteria. The aldehyde alone would have penetration difficulties. Together, they can do the whole job. (Combining single chain QAC with double chain QAC even enlarges their spectrum!). Finally, the product should carry buffering agents (preventing chemical incompatibilities) , stabilisers (in Europe, the shelf life should be on the label by means of an expiration date) , sequestering agents (allowing to work in hard water) and wetting agents (allowing to work in presence of organic matter). Last but not least the disinfectant should have a certain residual effect (preventing early re-contamination).
  
  

• Efficacy: bactericide, funghicide and virocide. This means you need a disinfectant (a -cide, not a -static !) that KILLS all bacteria, funghi , viruses and spores and leaves no room for acquiring resistance (or you will need to rotate). The disinfectant should equally do this job in presence of organic material. The AOAC standard testings are done with 5% organic matter and in 400 ppm hard water. Check if the label claims hard to kill viruses such as PCV2. For North America, an EPA claim for PRRS is advised.
  
  

• Versatility: ideally, the disinfectant should be ready to use for spraying, foaming (requiring a foam lance) and fogging (it should include the right carriers for hot or cold fogging).
  
  

• Safety: for people, animals and equipment. The latter means it should NOT be corrosive. To be safe for the environment, it should also be bio-degradable and hence not contain any heavy metals (like tin ).
  
  

• Cost efficient: this is not the cost per gal or Litre, but the cost DILUTED i.e; the cost / Litre x the dilution. The dilution is determined by the presence of active ingredients. Always check how many grams / Litre, oz/gal or % active ingredients the disinfectant contains !
  
  

• Stocking density: there are standards for stocking densities. Overshooting them may result in lower growth, more disease pressure and abnormal behaviour (cannibalism). Also the climate will determine the density.
  
  

• Prevention and extermination of rodents and insects: rodents don't only harm your farm (like eating insulation), they also contaminate the feed and spread diseases like Leptospirosis, Salmonella, Dysentry, … Blood sucking and biting insects also spread diseases. Manure and wet feed leftovers are the ideal breeding ground for flies.

Conclusion

This shortlist is just the top of the iceberg and the relevance of the various safety measures will differ from farm to farm. Very important is the "operational biosecurity" that refers to managerial hygiene practices or the management of the 3 P's : Products, Procedures and People . As antibiotics and medication are getting more and more under pressure, prevention is the way forward.

Source: CID LINES - June 2006