Biosecurity refers to the procedures used to prevent the introduction and spread of disease-causing organisms in poultry flocks. Because of the concentration in size and location of poultry flocks in current commercial production operations and the inherent disease risks associated with this type of production, it is imperative that poultry producers practice daily biosecurity measures. Developing and practicing daily biosecurity procedures as best management practices on poultry farms will reduce the possibility of introducing infectious diseases such as Avian Influenza and Exotic Newcastle as well as many others. Contract poultry growers should be familiar with the specifics of their company’s biosecurity protocols and work closely with company representatives to implement those programs. Before implementing biosecurity programs, contract producers should check with poultry company personnel to be sure the measures taken are consistent and compatible with their company’s policies.
How Microorganisms Spread?
The primary method of spreading disease causing microorganisms between poultry flocks is the use of contaminated equipment or exposure to contaminated clothing and footwear of humans. Infected animals, such as wild birds and rodents, can also be a source of disease for poultry flocks. Disease causing viruses and bacteria can be transported from one flock to another on bird transporting equipment, rucks, tractors and other farm equipment as well as egg flats and cases. Humans and animals are also important ways of transporting disease causing organisms. Disease causing microbes have been found on human’s clothes, shoes, skin, and hair. As a result, many hatcheries and breeder facilities utilize shower in nd shower out protocols as part of their biosecurity programs. Animals such as dogs, cats, mice, rats and ree flying birds are also known to be carriers of disease organisms. Insects such as flies, beetles, and mosquitoes are well known to be carriers of disease microbes as well. Another, but less risky form of transmission is through the air.
The following steps are a summarization of standard measures that poultry producers may use on their farms to increase the biosecurity of their flocks:
Keep Visitors to a Minimum
Human transportation of microorganisms is one of the more serious threats to biosecurity. Restriction of unnecessary human traffic is a major component of a sound program. Growers should restrict visitors and make sure that any visitor to their farm has a good reason to be there. Growers should provide protective covering such as boots, coveralls, and headgear to any visitors that work with, or have had recent contact with poultry. This would include friends, neighbors, relatives, equipment and utility service personnel. Visitors should never enter poultry houses unless approved by the grower or company personnel. Traffic through poultry houses should always flow from younger to older birds. One useful measure is keeping records of visitors that have been on the farm. If a problem arises, knowing who was there will help in limiting additional flock infections. Growers may post signs at the entrance to the farm indicating that entry to the farm and facilities is restricted. Poultry producers work to educate members of the local community of the risks to their flocks and the need to restrict traffic on their farms. This can be done by attending local community meetings or social events and speaking to groups and individuals about this subject. Print an article in the local newspaper about the importance of biosecurity for your farm and others. This can also help educate people regarding the seriousness of this issue.
Limit Visits to Other Farms
Poultry growers should refrain from visiting other poultry operations unless absolutely necessary. Whenever it is necessary to visit another farm, growers should be sure to exercise additional precautions such as showering and changing clothes before arriving and washing any vehicle before entering a farm. It will be very important for growers to wear protective clothing including boots, coveralls and headgear and to clean and disinfect all clothing and equipment before returning to their facilities. Showering and changing into clean clothes will also be necessary.
Animals Out of Poultry Houses
Animals can be carriers of poultry disease causing organisms. Growers should not allow pets such as dogs, cats or other animals in their houses. Some growers will allow their dogs to walk the houses with them, but this is risky because the dogs may have been exposed to other animals or birds that have been contaminated with disease organisms. Poultry houses should be kept as closed as possible to prevent wild birds from getting inside. Wild birds utilizing the feeders and defecating in the houses can be a source of disease.
Rodent / Pest Control Programs
Rats, mice, and insects such as flies and darkling beetles can carry and spread microorganisms. Growers should consult with their poultry company and practice effective rodent and insect control programs. Eliminating or reducing as many of these pests as possible will reduce the risk of contracting or spreading a disease.
Avoid Contact with Wild Birds
Poultry growers should avoid all contact with non-commercial sources of poultry including backyard flocks, fanciers, fairs, poultry shows, and markets. These types of poultry are seldom fully vaccinated for the major poultry diseases and they are often exposed to many types and flocks of birds. Non-commercial birds represent extremely high-risk contacts.
Employees should not be allowed to own their own poultry and neighbors with backyard flocks should be informed of the importance of getting sick or unhealthy birds to a diagnostic lab as soon as possible. Growers should also avoid wild birds such as ducks, geese and turkeys. Growers with farm ponds should be particularly concerned with the potential of carrying droppings from wild birds around ponds into their poultry houses. Wild birds are well known to be carriers of the avian influenza virus as well as other poultry diseases. Hunters should be sure they take the same biosecurity precautions as if they were visiting another poultry farm (i.e. showering, changing clothes, sanitizing vehicles, etc.).
Inspect Flocks Daily
Growers are required by their contract to inspect their flocks every day. Mortality should be picked up daily and disposed of in a timely and approved method. Stock-piling mortality and allowing carcasses to decompose before disposal increases the risk of spreading disease via rodents and insects. Growers should report increases in mortality or signs of health problems to their service representative immediately. This is required by contract and will ensure a rapid detection and response should a disease be present. Growers should check with their poultry company before using any vaccines, medications or drug treatments for a flock health problem. Timely reporting of health issues on a farm will not only help restrict additional infections, but will minimize losses to both the grower and the company.
Maximize the Environment
Maintaining litter in a relatively dry condition (i.e. 20%-30%) and providing good ventilation will help control microorganism numbers. Wet conditions combined with warm in-house temperatures provide a good growth environment for most disease causing organisms. Good ventilation also helps reduce microorganisms as fresh air entering and leaving the house dilutes microbe populations and removes them from the house. Poor ventilation can result in irritation of the respiratory tract of birds making them more susceptible to bacterial and viral infections.
Keep Areas Clean
Keeping grass and weeds cut around poultry houses and removing used equipment or trash is beneficial in keeping rodent and insect populations under control. Thick grass or weeds and old equipment provide refuge and habitat for rats, mice and insect pests that can spread disease. Spilled feed should be cleaned up regularly and not allowed to collect for long periods of time. Spilled feed around the feed bins will attract birds, rats, mice and insects.
Recognizing Disease Symptoms
It is important for poultry growers to be aware of signs of disease in their flocks. Early detection of contagious diseases can greatly reduce the impact and spread of that disease to other flocks. Clinical signs associated with the possibility of a disease in a poultry flock are:
- Lack of energy and appetite
- Decreased egg production
- Soft-shelled eggs or misshapen eggs
- Swelling of the head, eyes, comb, wattles and hocks
- Purple discoloration of the wattles, combs and legs
- Nasal discharge
- Coughing, wheezing and sneezing
- Lack of coordination in mobility
- Diarrhea
- Sudden or excessive mortality without clinical signs
The purpose of biosecurity is to prevent contact between layers and disease causing organisms
How organisms enter in farm:
- People are the main transporters of disease-causing organisms onto a farm. Most people visiting poultry farms have had some previous contact or involvement with poultry or with people who deals with poultry.
- It is most important not to allow visitors into poultry houses before they had gone through a shower and changed into clean clothes and shoes.
- Wild birds are carriers of viruses that cause Newcastle disease, IB (infectious bronchitis), coryza and MG (mycoplasma gallisepticum) and MS (mycoplasma synoviae). It is indeed not easy to keep wild birds out of laying houses but one should stop applying all possible means to achieve this. Nesting of wild birds on rafters and roof beams should not be tolerated.
- Feed wastage at feed bins is especially bad and wild birds get to know feeding spots.
- Rats and mice are carriers of a bacterium know as Salmonella enteritidis and eggs that are contaminated with those organisms are not allowed to be marketed. Those organisms are difficult to control and cause diarrhoea in humans.
The role of sanitary conditions
- Sanitary Conditions: This means cleanliness and the removal of waste, dust and material such as fats and oils in all working areas. These materials provide protection to bacteria and viruses, for example the Newcastle disease virus can survive for several weeks when protected against the sun and disinfectants.
- Disposal of Dead Birds: These should be disposed of in a proper manner, for example incinerated or placed in mortality pits with tight fitting lids to keep flies out. Dead birds harbour viruses and bacteria.
- Control of Flies: It is most important and should take place at their breeding sites. Wet manure provides an excellent medium for flies to breed in and every effort should be made to prevent water leaks onto manure under the cages. Fly control on a layer farm is also most important to prevent fly marks on eggs.
Stimulate Immunity to Control Diseases
A vaccine contains the viruses of a disease in a weakened form. When these are given to the hens by means of a spray or in the drinking water, it stimulates the production of antibodies. The most common route of administration by which the vaccine can enter the body is through the mucous membranes of the eyes or mouth and then into the bloodstream (eg vaccines administered by means a spray or in the drinking water). The circulating blood passes through organs that have the ability to make antibodies against these bacteria or viruses. The antibodies are very specific for the agent that was used to make the vaccine: Castle disease virus, an IB or Gumboro virus etc. These antibodies then circulate in the bloodstream and assist in protecting the cells of organs that will be invaded by the virus.
The antibodies recognize the virus strain that was used to make the vaccine and that means they will immediately attack that particular virus whenever it enters the bloodstream in future. They make it armless by binding to the virus. Antibodies are proteins and thus not stable compounds. Their concentration (numbers per ml) decline over time and it might happen that they can be overwhelmed if large numbers of the virus invade the bird. Therefore layers have to be vaccinated with certain intervals to ensure that their antibodies remain on a level sufficiently high to protect the birds against diseases that are prevailing in an area.
The antibody level for a particular disease (also known as the titer count) is therefore a good indication of the degree of protection against that disease. Bear in mind that antibodies are produced specifically in response a particular virus strain, which means the strain that was used to make the vaccine. It does not protect against another strain of the virus or to viruses causing a different disease.
Important Considerations
- Health of the Birds: Only healthy birds must be vaccinated. A vaccine contains the disease causing organism and it places a stress on a bird when those organisms are actually put into its body. In some instances birds would indeed show slight signs of the disease for which the vaccine is being applied. The formation of antibodies is poor in unhealthy birds and they are not well protected.
NB- Organs involved in the production of antibodies include the thymus, bursa of Fabricius, bone arrow, the spleen, Harderian gland, cecal tonsils, Peyer’s patches in the intestinal tract and Meckel’s diverticulum - Handling vaccines for spraying or aerosol:
- Equipment must be clean and tested for operation before mixing the vaccine solution because live vaccines have a limited lifetime.
- Ensure that cold chain has been maintained and check expiry dates and that the number of doses matches the number of birds to be vaccinated. The level of immunity depends on the activity of the vaccine and that the correct amount of vaccine will be taken in by the hens.
- Ensure that the mixing water is free of chlorine or other disinfectants. The organisms in the vaccine will be killed by a disinfectant. (During house cleaning disinfectants are used to kill probably the very same organisms that were used in the preparation of the vaccine.)
- When spraying make sure that the recommended spray nozzle is on so that droplet size will be correct. The size of the droplet determines how deep the spray will penetrate into the respiratory system of the hen and reach those organs that have to be protected against respiratory diseases.
- It is most important that all birds receive the correct dose of the spray so that the immune development will be according to the required level. Birds should thus be sprayed twice to
ensure the same level of immunity in all birds. (Birds with poor immunity will develop the disease when the virus makes contact with them and will serve as a source of contamination for other birds.)
Author: Dr. Rajesh Kumar Singh
Email: rajeshsinghvet@gmail.com
