白肉雞生產系統環境因子監控暨家禽大腸桿菌毒力因子調查

Abstract

自2011年3月至2012年年4月，至嘉義縣、宜蘭縣、新竹縣、桃園縣七個白肉雞場進行，包括雞舍中二氧化碳、硫化氫、一氧化碳、氨氣、風速、相對濕度、溫度、墊料水活性、墊料pH值、雞隻體內大腸桿菌、梭菌、墊料內沙門氏菌、梭菌等環境因子的採樣檢測或測量。22批次生產效能數據中，育成率為86%∼99%，各週死亡率又以第一週及第五週較高。結果發現，二氧化碳濃度與雞隻體內大腸桿菌對於白肉雞育成率有影響，若二氧化碳若超過1,500 ppm則育成率會明顯低於97%（P<0.05）。雞隻體內腸道與肺部大腸桿菌的存在，亦與育成率高低呈正相關（P<0.05）。此外，雖然氨氣、墊料水活性度及墊料pH值並未直接與育成率相關，然經由Pearson積差相關分析結果顯示，此三變數因子皆與大腸桿菌呈正相關（P<0.05），因此若氨氣及墊料水活性度、墊料pH值過高，尤其根據費雪精確檢定結果，知道當墊料水活性度在0.9aw以上或墊料pH值高於8時，將導致大腸桿菌較易滋長，也會間接影響育成率的結果。 欲了解家禽病原性大腸桿菌於雞隻肺臟與腸道之毒力因子分佈是否有差異，結果顯示，來自欲淘汰或死亡雞隻的大腸桿菌，肺臟與腸道分離株其毒力因子盛行率無顯著差異。表示可能可以由雞隻糞便中分離的大腸桿菌來預測發生呼吸道感染的大腸桿菌之性狀。毒力因子以帶有鐵運輸基因、帶有螯鐵蛋白受體基因、螯鐵分子受體基因、增加血清存活基因、帶有蛋白分解酵素基因與帶有溫度敏感的血凝素基因的大腸桿菌盛行率較高，皆有50%以上。而抗藥性表現部分，有60%以上的分離株皆對Erythromycin、Amoxycillin、Ampicillin、Tetracycline、Sulphamethoxazole/Trimethoprim、Nalidixic Acid、Neomycin、Oxolinic Acid、Florfenicol及Streptomycin等10種抗菌劑有抗藥性，因此對抗菌劑的抗藥性廣泛存在實為家禽產業一大隱憂，應做好監測抗菌劑的審慎使用以避免抗藥性的傳播。

In this project we have completed the monitoring of the environmental quality include temperature, humidity, wind speed, carbon dioxide, carbon monoxide, hydrogen sulfide, ammonia, litter water activity, litter pH values, water quality, Clostridium, Escherichia coli of poultry, Clostridium, Salmonella of litter and so on of five targeted chicken farms. The seven farms were located in Hsinchu County (3 farms), Taoyuan County (1 farm) , Ilan County (2 farms) and Chiayi County (1 farm). The livability of chickens in the five farms was from 94% to 99%. The results showed that the carbon dioxide and Escherichia coli of poultry did affect the livability of chickens. If the carbon dioxide was over 1500 ppm, the livability of chickens would be distinctly less than 97% (p<0.05). And the Escherichia coli of poultry were also significantly correlated to the livability of chickens. Although ammonia, litter water activity, and litter pH values were not direct correlated to the livability of chickens, through a Pearson correlation coefficient, the results revealed that ammonia, litter water activity, and litter pH values all were correlated to Escherichia coli of poultry, The above-mentioned three factors could indirectly relate to the livability of chickens. The increase of ammonia, litter water activity, and litter pH values accounted for growth of Escherichia coli. Escherichia coli is strains cause chicken respiratory tract causes, colibacillosis, even cause extensive mortality in poultry flocks, it was called avian pathogenic Escherichia coli. Recent reports showed that the avian pathogenic Escherichia coli is associated with certain virulence genes (sitA, irp2, iroN, fyuA, iutA, ompT, cvaC, iss and tsh). Identification and characterization of these genes are essential to implementing efficient disease control and prevention systems. The aims of the study were to identify the virulence genes and the antibiotic resistance of avian pathogenic Escherichia coli strains in Taiwan. And determine the difference of antimicrobial sensitivities, distribution of virulence factors between avian pathogenic Escherichia coli from lung and Intestinal of chicken.There were 60 Escherichia coli collected from chicken in six farms.The PCR of the tested samples revealed a higher prevalence of the following genes: sitA 90%, iutA 90%, iss 88%, iroN 63%, ompT 62% and tsh 57%. The study of antibiotic susceptibility profiles showed more than 60% resistance levels against Erythromycin, Amoxycillin, Ampicillin, Tetracycline, Sulphamethoxazole/Trimethoprim, Nalidixic Acid, Neomycin, Oxolinic Acid, Florfenicol and Streptomycin. The resistance rates of virulence factors and antimicrobial both had no significant difference between avian pathogenic Escherichia coli from lung and Intestinal of chicken. The indiscriminate use of antibiotics may increase the risk of development of drug-resistant Escherichia coli strains in Taiwan. Therefore, by monitoring flocks of resistance patterns of Escherichia coli, to in order to reduce the generation and dissemination of Escherichia coli.