The identification of risk factors for Salmonella contamination in broiler farms in northern Taiwan and the survey for Salmonella contamination of poultry feeds in Taiwan
Date Issued
2009
Date
2009
Author(s)
Huang, Huang-Chi
Abstract
Salmonella is an important pathogen in terms of zoonoses, poultry has been thought to be one of the major medium for human salmonellosis. Broiler chickens are one of the most commonly consumed chicken breed in Taiwan, therefore monitor it’s rearing and feeding conditions are very important. In order to alleviate the risk at commercial broiler chicken farms, a questionnaire based retrospective case-control study was conducted to identify risk factors with Salmonella contamination during the broiler rearing period. Forty-one broiler farms in northern Taiwan were studied from April 2008 to May 2009, included 14 open-sided and 27 wet pad cooling system housing type of chicken farms. All of the flock size was larger than 10,000 and only one house was studied in each farm. Through preliminary study, methods for the investigation of the broiler farms risk factor were established. Samples were taken at three consecutive time-points, visceral organs of chickens and feeds were also collected for further analysis. The results showed a flock positive rate of 56.1 % and the housing type of farms did not have a significant effect on Salmonella contamination (p >0.05). Through data analysis, odds ratios of ten risk factors indicated that thry may associate with the decrease in poultry farm contaminations although not statistically significant. These risk factors includes: (1) pad cooling system house which are single layered instead of multiple; (2) the entrance of the farm is locked; (3) none-tap drinking water for animals are pre-treated; (4) dog/cat feces are regularly cleaned in the farm; (5) workers outfits are changed and cleaned on a daily basis; (6) the farm is separated from the outside by a wall; (7) a single indoor room available for changing clothes and cleaning hands before entering the chicken house; (8) The cages used for transporting day-old chick are not reusable plastic cages; (9) a single source for day-old chick; (10) molds or coagulated litters are removed before use. Moreover, the weather factor of northern Taiwan is also worth mentioning, since contamination of Salmonella in broiler farms is significantly higher in colder seasons (p <0.05) .ince contaminated poultry feeds may aid in the process of Salmonella spreading in poultry farms, an investigation of poultry feeds were also performed. Different sampling sites and isolation treatment methods were compared. The result shows a total Salmonella isolation rate to be 7.6 % (59/778), flock positive rate was 21.4 % (33/154). Feed samples included 16 different brands, Salmonella were isolated from five of the brands. The data analysis showed (1) isolation rate of different brands are significantly different; (2) isolation rate of feed troughts from broiler house showed a significantly higher isolation rate than from other types of poultry; (3) not taking sampling site into account, breeder chicken feeds have a higher contamination rate than other types of feeds; (4) Overall, the best culturing medium for Salmonella isolation from chicken feeds is to use RVS plus XLD. (p <0.05)。
Subjects
Salmonella spp.
salmonellae
broiler
risk factor
odds ratio
feed
feedstuff
SDGs
Type
thesis
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