Biosecurity is crucial and essential for the safe and profitable production of all types of livestock, but poultry production is especially at risk for the following reasons

biosecurity, programme, healthy, poultry, livestock, africa, bird, chickens, fogging, disenfectant, cleaning, drinkers, eggsBiosecurity is crucial and essential for the safe and profitable production of all types of livestock, but poultry production is especially at risk for the following reasons


Modern poultry production is highly intensive with fast throughput and short turnaround times for batches of birds

There is a heightened risk of disease development and spread on typical multi-age farms and especially for young birds newly established in poultry houses vacated by mature flocks sent to market or culled

The continuous threat of importing disease carried on vehicles that have previously stopped at other farms during delivery of new birds and feed or taking broilers out to the processing plant and eggs out to packing sheds

High risk from large transient and contract work forces in close contact with birds and employment history at other farms

The add on extra risk from contract workers brought in to carry out specific tasks like catching and vaccination

Specific threats from poultry diseases such as avian influenza established in Asian wild bird populations and backyard poultry

Acute susceptibility of poultry to rodent-borne infections like salmonella, fungus spores causing aspergillosis and mycotoxins produced by specific mould fungi


Start as you mean to go on


‘Biosecurity’ is a much used and abused word, easy to talk about but extremely difficult to establish and maintain. Biosecurity programmes must be strategically planned, far-reaching and underpinned by the basic principles and rules of good hygiene. Ultimate long-term success will only be achieved with clear-cut priorities and correctly sequenced steps.

Sustainable biosecurity means beginning with an absolutely disease free environment and then erecting and maintaining a hermetic (sealed) cordon around the entire farm. As an extra precaution separate biosecurity cordons are established around each individual poultry house as additional barriers to infection.

Only buy poultry stock from known disease-free sources. All incoming vehicles must be washed down and tyres and wheel arches sprayed to ‘run-off’ with disinfectant. Drivers should remain in the cab or otherwise be provided with waterproof protective clothing and boots.

The focal point of any biosecurity programme is the provision of pest and disease free housing for birds. New birds brought onto the farm must be isolated from other birds for fourteen days while blood tests, vaccination, preventative medication and anti-parasitic treatment are carried out. In the meantime the existing flock should be removed from the intended house which is made biosecure before the new flock installed.



Don’t rely on disinfectant


Disinfectant use is essential but not a panacea for all ills or a magic cure on its own. Cleanness of surfaces to be disinfected and application methods employed rather than the actual chemical disinfectant used will usually determine whether a disease free house is achieved.

Dirt and organic matter such as dried and hardened faeces, mucous, feathers and spilt feed will inhibit disinfectant action because there must be direct contact between the biocide and the pathogen.

Modern disinfectants are put through stringent laboratory tests such as the Kelsey Sykes Test that simulates real working conditions in the poultry house. These assess biocidal activity in the face of repeated ‘challenge’ by organic matter and effect of hard water caused by high levels of calcium or magnesium salts.

Many chemicals including strong acids and bases, chlorine generators, phenols, aldehydes, quaternary ammonium compounds, iodophors and peroxygen compounds possess disinfectant action. Some such as iodine based compounds have a long history of use but limited action and a relatively narrow range of kill. Others like formaldehyde though widely used in the past are now largely avoided for reasons of safety to both birds and poultry workers.

Modern disinfectants are potent biocides with broad-spectrum activity and a long contact time in which to kill pathogenic microbes. For instance, peroxygen compounds that disrupt and destroy microbes through oxidation reactions will destroy most types of pathogenic microbe. These include bacteria (e.g. Salmonella typhimurium and Escherichia coli) viruses (e.g. avian influenza and infectious bronchitis) and fungi (e.g. Aspergillus fumigatus and Canida albicans). Contact time is increased by the addition of a surfactant. Surfactants are surface-active chemicals that lower the surface tension of the diluted disinfectant mixture to increase penetration and spreading power of water-based biocides.


Facts about fogging


Power washing with detergent will remove dirt and organic matter from accessible surfaces and leave them clean and ready for disinfectant action by ‘wet’ spraying. But poultry houses are typically riddled with ‘nooks and crannies’ – fan shafts, ducts and other areas inaccessible to standard cleaning and disinfectant spray programmes. These out of the way areas can only be ‘covered’ by space spraying using droplets small enough to penetrate into the smallest crack and corner. ‘Dry’ application of disinfectant by thermal (hot) fogging is the only application method that can realistically achieve this goal.

Thermal foggers operate by vapourising the liquid disinfectant mixture that subsequently issues through the fogging pipe as mixture of hot gases. On contact with cold air it condenses into a mass of tiny droplets which form the fog.

Benefits of hot fogging disinfectant arise from two basic laws of physics that relate droplet number to droplet size, and suspension time with droplet size:

Hot foggers produce droplets of 5-25μ in diameter. The larger droplets cover the walls, floor and ceilings to provide residual disinfection. The smaller droplets stay suspended in the air for space disinfection, thus acting against airborne spores and dust-borne infections. Disinfectants with a relatively high vapour pressure perform best during hot fogging, although fog-enhancing chemicals are available to improve performance of a wide range of disinfectants. Disinfection by hot fogging may be achieved at very low volume application rates of 20 litres/1000 cubic metres.

Fogging may also be used to control insect pests and pathogenic microbes in bagged/sacked feed storage areas. Ideally it should be carried out when the store is empty. But it can also be used as an emergency measure when the store is full, provided the biocide is cleared for such use and the bags/sacks are stacked with ample space.

Thermal foggers can be operated in the hand-carried mode, in a stand-alone mode within the building, or from outside by fogging through ports in the walls. If hand-carried the operator should start at the far end of the building and retreat carefully to the exit as he/she fogs. Full protective clothing including a respirator must be worn.



Rolling programme



* Immediately after emptying the building of all birds, but before embarking on the cleaning programme, producers can make a short-time aerosol application of insecticide (pyrethroid or other appropriate active ingredient). This will control all arthropod (insect and mite) pests, including those that are air-borne or resting up in cracks and crevices. Swift application, while the building is still warm, ensures good control while the insect and mite pests are still present and active.





Maintain the biosecurity cordon

With the healthy new flock of birds safely installed in a pest and disease free building it is now up to the producer to see it stays that way using utmost caution coupled with a dose of ‘common-sense’ good hygiene practice.

Keep visitors to an absolute minimum. Provide all authorised personnel with waterproof clothing and boots that can be easily and effectively cleaned and changed regularly.

Provide a ‘foot-bath’ of disinfectant at the entrance to each house and a brush for cleaning boots prior to immersion in the ‘foot-bath’. Renew the disinfectant daily. ‘Foot-baths’ are not a practical essential but also a constant reminder to staff about the need for constant vigilance to maintain biosecurity.

Wash down and disinfect all vehicles entering the farm so that they come in clean and leave dirty. Schedule and route those vehicles unloading at multiple points on the farm so that they stop first in areas of highest vulnerability (young birds), and then move to areas of lower vulnerability (e.g. mature flocks).


Scrub drinkers daily with an appropriate disinfectant mixed with detergent. Iodine is good because it removes algae and slime, is of low toxicity to birds and its brown colour allows managers to check that the job has been done. Remove all dead birds quickly and carefully. Seal in bags for disposal and incinerate well away from the poultry house to prevent cross contamination with feathers or ash.

One potentially high risk that often goes unnoticed is potential sources of infection within the farm environment, outside of the poultry house but posing threat of re-infection. For example, vegetation between houses should be well managed or preferably replaced by concrete that does not harbour infection so readily and is easily cleaned. All cleaning programmes must include such areas as follows.

Clear all equipment, rubbish and other vermin attracting material away from poultry houses, and do not park vehicles and equipment from clean-up programmes near to houses lest they cause re-infection. Remove all droppings, litter and other bedding to points at least 200 metres away from the house and stack so that it cannot be dispersed by wind. Store hay, straw bales and other bedding material in dry, closed places so that poultry houses are not at risk from wind-borne fungal spores released from damp and musty material.

Biosecurity programmes need to be well planned and encompass the entire farm environment as well as recognising hazards from outside. But even the best-laid plans will go awry if procedures are not followed to the letter. For instance, carrying non-disinfected fittings back into the fogged poultry house or introduction of litter after fogging will negate the whole programme.


Dr Terry Mabbett

Template Design © Joomla Templates | GavickPro. All rights reserved.