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CHAPTER 4
HEALTH, HYGIENE AND ROUTINE MAINTENANCE

Poultry Rearing Hygiene

The production of healthy poultry depends on the maintenance of health and hygiene throughout the entire production system. This includes the maintenance of health at the point of production of the live birds. The following are examples of measures which can be taken to ensure good hygiene and to prevent disease at the farm:

External contamination

There are several sources of external contamination which should be prevented, reduced or controlled. These include:

Inspection of Live Birds before Slaughter (ante mortem inspection)

In poultry processing, ante and post-mortem health inspection of birds is essential. In the tropics, this is usually carried out by a qualified veterinarian, meat inspector, public health inspector, environmental health officer, police officer, customs officer or whoever may be appointed within the legislation. These trained, qualified staff usually operate under the Veterinary Services or Ministry of Health, depending on territory. This is needed to protect the health of the public and enable the veterinarian to monitor the health status of the flock. Remedial action on a wider scale may be taken if necessary.

Poultry intended for slaughter should undergo ante-mortem health inspection within 24 hours of slaughter and this should be repeated if the birds are subject to delay. Ante-mortem health inspection at the poultry processing plant may be restricted to detecting injuries received in transport if the poultry have been inspected fully at the farm of origin within the 24 hours immediately preceding the ante-mortem health inspection and found to be healthy.

The ante-mortem health inspection should determine:

Microbial Implications of Slaughter And Processing

Although domestic poultry have social habits which include preening of feathers and attention to personal cleanliness, these are not well developed. Poultry normally co- exist with considerable numbers of micro-organisms, insects, parasites, dirt, dust, faeces, all manner of filth and feedstuff among their feathers and on their skin. The skin protects the main body from microbial invasion but if this is damaged, it may lead to infection of the underlying tissues, organs and body as whole reducing the value of the carcase. Similarly, the alimentary tract contains a very large number of organisms usually held in a sensitive balance which, if upset, can lead to digestive problems resulting in a change of faecal consistency. This may assist in the spread of alimentary infection to other birds in the flock and, as will be described below, to human beings.

Many precautions can be taken to assist with the microbiological condition of poultry and the poultry meat they produce. These precautions should start at the producers premises where young birds are raised. The producer should take note of the advice offered by the veterinarian or extension officer about design, operation, management, cleanliness and general health of the flock and its housing. Great attention should be given to seeking veterinary advice should the flock become sick. Poultry housing should be properly separated from other animal housing, human habitation and their animals. It should be kept clean while the birds are growing and thoroughly disinfected once the birds have gone for sale and slaughter. The containers for the birds should have been disinfected before birds are placed in them and the vehicle should have been similarly treated. Attention should be given to the cleanliness of the livestock handlers, their clothing and footwear. They should be discouraged from keeping their own poultry at home (see Chapter 1).

Live birds should be handled quietly, kept off the ground and slaughtered using properly designed, maintained and cleaned equipment in a properly designed, maintained, cleaned and managed building. Attention is drawn below to the concept of cross contamination of poultry carcases by micro-organisms. The most important areas to monitor are the reception areas for the live birds, the scalding tank area, the defeathering machine (which can harbour undetected micro-organisms for years) and the chilling tank.

Given the nature of the bird as described in the first paragraph, it is not difficult to see the consequences of birds flapping, touching and struggling in confined spaces in the likes of the reception and slaughter areas of the processing plants. Wash water from scalding and plucking contains many micro-organisms which can be distributed by aerosol as well as in flowing water. Poultry are processed rapidly and eviscerated through a small opening in the body cavity. The alimentary tract can split easily, spilling its contents over the carcase on both the outside and inside. Process water, such as used in washing, chilling and further processing can become contaminated easily. From the whole process, surfaces in the building and on machinery can become contaminated as can the hands of processing operators and their processing implements. Each has the potential to contaminate the poultry carcases further.

The consequences of carcases contaminated with micro-organisms on product quality and consumer health are well documented. They fall into two main categories. Those which cause spoilage of the meat and those which transmit pathogenic micro- organisms to the consumer.

There are many forms of spoilage organisms but Pseudomonads are the most important. They are found in large numbers on feathers but rarely in the alimentary tract. In the living bird, their activity is kept under control by the physical barrier of the skin, competition for suitable nutrients from other micro-organisms and the temperature of the skin which is too warm for their optimal growth. After slaughter of the bird, they are destroyed in large numbers by the scalding tank as most do not grow or survive above 28°C. Those that do however, can re-contaminate other carcases in subsequent processing operations. Unless carcases are washed thoroughly in super-chlorinated water and chilled promptly, the Pseudomonads may be present in sufficient numbers to overcome competition from other micro-organisms, and grow at their optimum temperature. Spoilage of the carcase may result.

Pathogenic organisms in poultry are responsible for gastro-intestinal disturbances in humans. Salmonella spp are found in the caeca of young birds and are transmitted from bird to bird at all stages of growth, handling and transport of the live bird via a faecal route. Cross contamination may occur during processing at the abattoir. Under proper processing conditions, Salmonellae fail to grow rapidly in the processing plant and at temperatures below 7°C hardly at all. Rapid chilling of the carcase therefore, is recommended. Salmonellae may continue to thrive on carcases subjected to temperature abuse and may then become a hazard to health.

Salmonella spp attract the most publicity but are not the only organisms responsible for food poisoning. Clostridia spp, particularly Clostridium perfringens are also found in poultry arriving at the processing plant. They, too, are found in the caeca and colon of live birds. Although they infect live birds and cross contaminate at the processing plant like Salmonellae they are found, fortunately, in small numbers at the end of a processing operation provided operations are carried out efficiently. They do not grow well below 15°C and provided the bird is kept properly chilled and is well cooked at home, no real danger of food poisoning exists. However, some micro-organisms can withstand normal cooking temperatures and, if cooked poultry is left in warm conditions, can multiply quickly to cause food poisoning.

Staphylococcus aureus and Campylobacter jejuni are also important micro-organisms in poultry processing. They survive within the body of poultry and readily cross contaminate other carcases during processing. Once again, prompt chilling is necessary if their numbers are to remain at safe levels after processing.

Regrettably it is not possible to hope that a thorough final wash will be sufficient to clean poultry to a safe level of contamination. While many bacteria are washed away during processing, sufficient remain to cause problems if carcases are not properly handled. Washing is not a very effective way of removing bacteria. They are found in the bottom of feather follicles and many creases within the skin which hold water, positions which are difficult to clean and conditions conducive to microbial growth. Simple washing is insufficient to remove all these organisms. Bacteria also attach themselves to the skin by a mechanism which is not fully understood. They form a film which is not removed by scalding or chlorination.

Operational procedures are introduced to overcome these problems. For example, dry plucking, followed by washing and rapid chilling or dispatch of New York Dressed birds is recommended in the smallest scale model of poultry processing discussed in this report (Model 1 – 50 birds/day). This system ensures the intestinal micro- organisms are contained until the carcase is ready to be cooked. Cross contamination with other carcases is prevented during processing. Special instructions on use of New York Dressed carcases must be given to the customer to prevent transfer of microbiological problems elsewhere. In practice these are thought to be fewer than might be expected. The second scale of operations discussed in this report (Model 2 – 200 birds/day) uses a system of wet scalding, defeathering by plucking machine and chilling in a tank of cooled or iced water after evisceration. Although potentially the most difficult system to control, the scale is such that all operations can be closely managed by technical staff. Cooling by ice cold spray (an alternative to cooling by slush ice) would be uneconomical. Carcase cooling in the third scale of operations, (Model 3 – 2500 birds/day), is similar to the second but offers a choice of three chilling methods after evisceration. Carcases may be spray washed followed by air chilling in a cold room (the preferred system of operation but requiring more management) or chilled in a tank of cooled water or slush ice. Once again, the scale should be such that the operation can be closely managed by technical staff using a properly established operational code of practice.

Inspection of Live Birds after Slaughter (post mortem inspection)

All parts of each bird should be inspected immediately after slaughter. To do this all parts of the carcase should remain identifiable until the inspector has declared the carcase fit. This is best done if the viscera is left attached to the carcase.

The post-mortem health inspection should include:

The inspector is looking to see if the carcase is fit for human consumption. He may find an indication of:

If any of these conditions are found, the carcase should be set to one side and disposed of according to the nature of the condition. For example, should the bird have suffered a breast scab, then the rest of the carcase may be salvaged. If the carcase shows signs of jaundice, then it should be condemned and incinerated or deeply buried with lime. Other conditions are sometimes found and the qualified veterinarian will be able to recognise them and deal with them accordingly.

Staff Health

All staff who work in the poultry plant are handling meat which will eventually be eaten. The opportunity exists, therefore, for transmission not only of pathogenic organisms associated with poultry but also diseases associated with the operative. Poor handling techniques can also lead to cross contamination of spoilage organisms and reduce the shelf life of the product. As a consequence, there are several rules to be followed which can help to reduce these risks.

Every person who works where meat is handled should:

Every person who works where meat is handled should not:

No person should handle meat or be near it if:

Every person who is likely to handle meat should undergo an annual medical examination and receive a certificate from a qualified medical practitioner which states that there is no objection to that person handling poultry meat. The certificate, which is a confidential document, should be shown to and lodged with the manager of the poultry processing plant and may be shown to the official veterinary officer on request.

Plant Sanitation and Maintenance

These functions have been combined in this document to provide a regular schedule of activities.

Plant sanitation

During production, waste materials collect on the surfaces of the building and equipment. These are an ideal media for micro-organisms to grow. Growth will occur if the waste is not properly removed. The micro-organisms may be transferred from their growing place to the product through disturbance by people touching the dirt and directly touching the product. The product may also be contained by coming into contact with dirt and by incorrect cleaning procedures which simply move the dirt and micro-organisms about without destroying them.

As an activity, cleaning is a complete science in itself and well beyond the scope of this document. Nevertheless there are certain general principles followed which are universal to most food factories. These involve the use of the following which, in themselves, may be sanitizing agents:

These carriers may be used in conjunction with certain chemicals eg:

It is perhaps worth recording the main classes of sanitizing agents and some of their characteristics to give some idea of their usefulness in poultry processing plants.

Chlorine and chlorine-based products, including hypochlorite compounds: These are probably the most suitable disinfectants for food plants. They act rapidly against a wide range of micro-organisms and are relatively cheap. They are used in concentrations of 100–250 mg of available chlorine per litre. They are corrosive to metal and have a bleaching action. After adequate contact time, they should be rinsed off. They are readily inactivated by organic materials so they should be used after the premises have been cleaned rather than as an initial cleansing agent. They may leave an odour in the building which may taint the meat if not properly rinsed off after use.

Iodophor compounds: These are always blended with detergents in an acid medium. They have a rapid action and a wide range of anti-microbial activity. They are of intermediate cost. They are used in concentrations of 25–40 mg/1 of available iodine at a pH of less than 4. They give a visual indication of their effectiveness as they lose their colour when the residual levels have dropped to ineffective levels. They are not toxic when used at normal concentrations but since they can combine with substances in food to cause taint, they should not come into contact with food or their contact surfaces. They are corrosive and should be rinsed off after a suitable contact time. Like chlorine-based compounds, they are readily inactivated by organic materials so they should be used after the premises have been cleaned rather than as an initial cleansing agent.

Quaternary ammonium compounds: These have some detergent characteristics. They are non-toxic, colourless and relatively non-corrosive to metal. They are not as effective against gram-negative bacteria as are chlorine-based disinfectants and iodophors. Thorough rinsing is necessary as the compounds adhere to surfaces. They are used at concentrations of 1:50 to 1:250, depending on the hardness of the water. They are expensive to purchase but are useful where it is necessary to use an alkaline disinfectant, where odour, taste and toxicity are to be avoided and persistence is required.

Amphoteric surfactants: These are of a comparatively new class of disinfectant with both detergent and anti-bacterial activity. They are non-corrosive, tasteless, odourless and of low toxicity. They are not as effective as chlorine-based or quaternary ammonium compounds. They are expensive and require good rinsing after use. They are effective against a wide spectrum of organisms.

The delivery of the sanitizing solutions may be achieved through the use of:

There can be no general recommendations made about use of the most appropriate sanitizing method for each situation. Similarly, the use of particular chemicals (brand names) cannot be recommended since they are a combination of chemicals with the potential for synergistic activity or reaction. They should be changed frequently. The reasons for this can be given in the following historical example:

In one factory a particular brand of disinfectant was used in the high pressure washer. The disinfectant was delivered through a fine nozzle which formed an aerosol. On the edges of the spray, certain micro-organisms were subjected to very weak concentrations of the chemical and formed a resistant strain. The full user strength disinfectant was of little use and had to be changed.

All sanitizing agents should be handled in accordance with the manufacturers instructions. This includes the use of protective clothing, particularly overalls gloves and boots. This is important when using iodophor compounds as these agents may penetrate the skin, pass into the blood and accumulate in the thyroid gland.

In the tropics there is usually a severe shortage of sanitizing agents. The most frequently encountered are sodium hypochlorite (chlortabs), steam and sunlight. Severe mechanical effort in conjunction with cold water often remains the system of last resort. For the sake of simplicity, it will be assumed that these are the only agents for the foregoing. Poultry processing plants with access to a wider range of sanitizing agents should use them in accordance with the manufacturers instructions, change them when able and monitor both cost and efficiency.

Plant maintenance

In the context of the poultry processing factory, plant maintenance means that all equipment and structures are examined frequently and carefully, and serviced or maintained according to the manufacturer's instructions. It does not mean that repairs are made once things have gone wrong, failed, broken etc. Plant maintenance is necessary. A separate budget is required so that it can be carried out. It is intended that faults are found before they become critical and stop the production of poultry meat or affect its quality. Of course, machinery will break down unexpectedly and need to be repaired. There are several levels of repair which can be undertaken in the factory. For example, a broken poultry hanger can be straightened so that it causes no mechanical problems during a production session. It should then be repaired fully before the next day's work as there will be a continuing loss of productivity.

Sanitation and Maintenance Schedules

The following gives some idea of the sort of schedule that could be drawn up and followed to maintain efficiency of the poultry processing plants discussed in this document. The operations are accumulative ie the operations recommended for one period include those given for the previous periods. Some plants will not have some of the equipment and facilities which require attention. It is taken as read that all plants carry out the appropriate maintenance for that plant

As needed (during operation)

At the end of every slaughter session

Daily

Weekly

Clean cold stores, when empty.

Annually


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