BACTERIAL CONTAMINATES ASSOCIATED WITH COMMERCIAL POULTRY FEED FROM THREE DIFFERENT COMPANIES
Among raw food items of animal origin, poultry meat and poultry meat products are considered to be some of the most contaminated products offered to the consumer (Klinger, 1993). This is due to the relatively high contamination with various food-borne infection agents present on and in the product. More than 27 different species of bacteria have been isolated from normal, ready to cook, poultry meat (cox and Bailey, 1987). A large number of publications incriminate poultry as origin of food – borne infection out-breaks.
Modern production facilities for poultry tend to be large and intensive. A very large number of birds are maintained in each production unit. Under these conditions, it is nearly impossible to present the spread of a microorganism, once it has measures to control contamination of poultry with pathogenic Microorganisms (such as salmonella, listeria, and campylobacter) are aimed, inter-alia, towards prevention of the infection or colonization of the birds on the farm by various means of inhibiting possible entrances of disease producing agents into the farm. High priority is given to decontamination of poultry feed, since all means employed to prevent infection will fail unless a supply of decontaminated feed is ensured.
The role of animal feed as a Vector of pathogenic microorganisms, in particular salmonella has been well documented ins the literature of the last decades, (Klinger and Lapidot, 1993). Feed ingredients of animals origin, such as fishmeal, meat and bone meats, slaughter foals and feather meals are reported to be usually contaminated. However, ingredients of plant origin, such as oil-seed lake meals, are also reported to be contaminated, albeit at a relatively lower frequency (WHO, 1993). In several countries, compulsory use of decontaminated feed is an integrate part of salmonella control in poultry in France, Sweden, U.S.A (WHO, 1992).
In the report of an expert group on animal feed stuffs in the U.K.,it was stated that: The three major potential sources of infection in poultry flocks are parent birds, the environment and feeding stuffs. Clearly, the breeding bird can be a source of initial infection, is unclear. In addition, the environment may become heavily contaminated and may be a cause in further transmission. However, it is difficult in the current salmonella enteritis outbreak to assess the contribution of feeding stuffs relative to other sources at the present time. this appears to be a well established zoonosis in which an infection, possibly introduced by feeding stuffs, has resulted in further vertical transmission and widespread environmental contamination (Lamming, 1992).
The poultry industry, more than that of any other farm animal branch, depends largely on industrially produced feed constituting the sole diet of the birds. Decontamination of the feed is therefore, essential and is an integral part of the hygienic chain food manufacturing practice. Methods developed for this purpose are based mainly on thermal treatment, usually employed ins the form of pelleting (Combination of humid heat and pressure) (WO, 1989 and 1990). This treatment is effective only if a sufficiently high temperature is employed for enough time to eliminate the pathogens completely and if the pellets are protected during cooling from decontamination by employing filtered air for prevention of dust and by preventing condensation.
Chemical treatment, utilizing organic acids such as tonic or propionic acid, is also common, both with good results (WHO, 1989 and 1990). This is effective under the condition that a sufficiently highly concentration of acids or their derivatives is applied (often too costly for the poultry industry) and that sufficient time is available for their diffusion into the feed grannles. However, their use is accompanied by corrosion of equipment as well as by environmental hazards, requiring protective face and body gear for the personnel involved.
Limitations imposed on the feed industry will affect the decision on the method to be employed. The method should be effective, safe form a spoilt of view of public health, performance and quality of the products, as well as for the health of consumers. And all this at the lowest cost possible. The economic aspect is of immense importance since the poultry industry is calculating its profits in terms of very small increments.
One proven alternative method for decontamination of ionizing radiation (Campbell et al, 1986, coming, 1983; Ho et al; 1979, Klinger and Lapidot, 1993; Kocher, 1991; Lay et al, 1969 and Mossed, 1979)> This method presents several advantages. The major advantages are that the method can be applied to products in their final commercial package or that it can be applied on line, using accelerators, to continuously flowing, commentated feed or feed components at very high throughout, and at relatively low costs. Recent calculations shows that irradiation treatment of poultry feed could increase the price of the feed by 3% and that of the broiler meat is tself, by 0.5 1% (WHO, 1991), one should note, however, that when irradiated with accelerated electrons, in free flow, precautions are needed to prevent decontamination.
Although feed is not food, it is declined practical (in some countries) to adopt food standards for a feed which is co directly linked to the final quality of the product as in the case of poultry and its feed.
Poultry feed ingredients are delivered in bulk and usually in very large quantities, conveyed directly from one site to another. The poultry industry relies on a supply of ready – to – use feed from a feed mill, constructed for handling very large quantities of different ingredients, including unloading, grinding of grains, mixing and usually pelleting of the mixed ration. All ingredients, excluding those added in micro-amounts, are stored in sibs, from which the materials are conveyed to the mixing facilities in accordance with computerized control of mixed ration. If the ingredients are irradiated prior to decontamination by special from decontamination by special measures, such as filtered air, to exclude dust and insects.
Different conditions prevail in facilities for small-scale poultry farms, where the packaging material s used for feed and or feed components are sacks made of plastic, laminated paper or gute. If such ingredients are to be irradiated in their original packaging, the following should be considered: (a) generally, at the dose required, commonly used packaging materials are satisfactory for irradiated products; (b) packing should be functionally proteive, (c ) where irradiation significantly alters the functional properties to a particular packaging material, or may result iin the formation of toxic substances which can be transferred by contact to the feed component, that packaging materials cannot be used. The choice of packaging materials may be restricted by regulation in the country where the product is produced and or sold. Packaging materials used must comply with relevant national and local regulations.
Poul;try feed components of plant and animal origin are commonly contaminated with microorganisms (Bacteria and moulds) and or insects. S the numbers and types of microorganisms and insects vary with the particular material the location of its origin, climatic conditions, encountered, harvesting, communiting, processing, storage and transport technologies employed, packaging used, and the general environmental and handling circumstances, including the nature and extent of quality control measures.
Elimination of Salmonella and of other enteric bacterial pathogens, such as particular types of Escherichia coli, and listeria monocytogens from feed components, can be achieve at relatively low absorbed doses. Micro-organisms belonging to the Enterobacteriaceae family are generally radiation susceptible and can generally be eliminated. (Begun et al, 1989; l fonly et al, 1986) Ho et al, 1981; Lapidot et al 1968).
The number of moulds, such as Aspergillus, pencillium, Fusarium spp. Is often reduced significantly at an absorbed dose of 5kGy. However, mycotoxins produced before the treatment are not significantly affected by radiation (El far et al, 1992; Kuline et al, 1983; Odaintten et al, 1980 and Radova et al, 1991). From the practical point of view, the absorbed dose of 3-7 kGy at the point of minimum dose rate within the product, s sufficient to decrease the number of microorganisms to an acceptable level, without causing significant chemical changes in feeds (Adler et al, 1978). It is known that lipids are attacked by free radicals which are formed upon irradiation and that peroxides and other oxidation products are formed under aerobic conditions in a way similar to the oxidation process. However, farm animal did treated with ionizing radiation are likely to be acceptable to the animal because irradiation at 6kGy forms only small quantities of oxidation products of fat in the feeds (Lapidot, 1979). It should be noted that effective absorbed doses required for greater than those needed for insects. Therefore, irradiation of poultry feed components for control of the micro flora will completely eliminate any insect present, at all stages of development (Lorenz, 19978).
It should also be noted that, if feeds or feed components previously decontaminated by heat treatment (Pelletization) or by other means (organic acids), have been recontaminated during cooling, handling and storage (usually at a low level), the radiation dose required for elimination of the added pathogens may be quite low and should be determined as a function of the residual counts. The fact that feeds or feed components have been irradiated should where required, be specified in proper documentation, using expressions such as “irradiated” or treated with ionizing radiation” with indication of the purpose, e.g. disinfection or decontamination. Thus the feed or feed component is not only to be identified as is also to be informed as to the purpose and benefits of the treatment (Eisenberg and Lapidot, 1978).
The purpose of processing feed grain is to improve their palatability, digestibility and overall feed efficiency. For many years, poultry stock-men sought to do this by grinding, crush rolling and soaking feed grains but since the late 50’s several new processing techniques have been used (McGraw – Hill encyclopaedia, 1992). Grinding and pelleting are the most common means of preparing feed for poultry (Leonard, 1981). Generally, results shore that grinding to a maximum moderately fine texture results in bet performance than when grains are finely grind (Church, 1988). Feed particles of different ingredients should be of since size so that birds do not sort on the coarse particles and leave the fine particles. Pelleting usually results in improved grain, partly because animals tend to eat more in a give period. Efficiency often is improved, sometimes because of less wastage with pellets.