Changes in microbial ecology during poultry production
Schreuder, Johanna Catharina
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Microorganisms, especially pathogens, play an important role in the deterioration of poultry meat and its products causing spoilage or food poisoning. The meat renders an ideal medium for the growth and progression of microorganisms originating from the environment on the farm (eggs and broiler), transport to the abattoir as well as the abattoir. As far as we know, no attempts were undertaken to determine the total microbial spectrum, including bacterial and yeast populations from the egg unto the chicken carcass after slaughtering. A historical review of the incidence and extent of microorganisms associated with poultry and it's environment is given in Chapter 1. The background of poultry production and contribution of microorganisms (for example pathogens and yeasts) are highlighted. In Chapter 2 a survey was undertaken to determine the incidence, extent and serotypes of different pathogens on and in freshly laid eggs as well as incubated eggs in the breeder broiler hatchery. In addition, the number of viable cells of bacteria and yeasts were also determined. Microbial counts on the dirty eggs predominated. A major decline in microbial numbers on the egg shells, however, were observed after 18 days in the incubator. The deduction in bacterial populations present on the egg shells after 18 days in the incubator, is ascribed to the constant fogging of the environment inside the incubator with clinafarm. The irregular gathering of eggs as well as the dirty hands of the egg collectors could have been the major contributors of the high counts on these eggs. The only pathogens obtained were Listeria and E. coli type 1.In Chapter 3 the microbial populations associated with the caecum and liver of broilers as well as with the environment were determined. Anaerobic plate counts reflecting the dominance of bacterial populations were constantly the highest ascribed to the contents of the gut. Salmonella, Staphylococcus aureus and E. coli type 1 were isolated from the caecum, however no Listeria were isolated. Salmonella and E. coli type 1 were isolated from the liver. The high incidence of pathogens associated with the broilers is an indication of the pathogens that enter the abattoir. These levels of pathogens, further increased during transport to the abattoir.In Chapter 4 the incidence and extent of microbial populations associated with broiler meat and the environment in the abattoir were evaluated. All the pathogens present on the farm were also observed in the abattoir. The main reasons for the similarity in the incidence of pathogens on the farm and the abattoir were ascribed to the transport from the farm to the abattoir, the process of slaughtering, equipment surfaces in the abattoir and people handling the meat. Aerobic plate counts predominated on the neckskin samples, equipment surfaces as well as in the water and air of the abattoir. E. coli type 1 clearly predominated on the neckskin samples as well as on the equipment surfaces, followed by Staphylococcus (U/reus and that by Salmonella. No Listeria isolates was, however, isolated from either the broiler farm or the abattoir, but was indeed observed on the egg shells from the breeder farm. Although a pattern reflecting the incidence of pathogens could be establish between the broiler farm and the abattoir, no comparison could be made with the eggs from the breeder farm and hatchery. This may be blamed on the sampling of insufficient number of eggs, or the lack of multiple repetitions. Despite the inability to detect the primary sources of pathogens the distinct possibility remained that the broiler farm was the main contributor towards microbial contamination and infection. Therefore, more effort is needed to control the diseases and infections on broiler farms, because in an abattoir you only get out what you put in.