Prevalence and Pathological Investigation of Different form of Colibacillosis in Commercial Broiler Chicken in Chittagong

Abstract

The aim of the present study was to determine the prevalence of colibacillosis in commercial broiler chickens in Chittagong. A total of 43 birds submitted to the laboratory of the Department of Pathology and Parasitology, Chittagong Veterinary and Animal Sciences University for disease diagnosis were investigated during the period January to February 2017. Colibacillosis was diagnosed based on pathological lesions observed in different organs during post mortem examination. Liver and cloacal swab samples were collected from dead birds suspected with colibacillosis. During collection of organ samples strict precautionary measures were followed to avoid faecal contamination. The samples were inoculated in to MacConkey agar and incubated at 37°C for 24 hours. Those producing large, pink colored colonies were suspected as Eschericia coli (E. coli) and subcultured on to Eosin methylene blue (EMB) agar to observe the production of characteristic metallic sheen colonies. The results showed that 34 out of 43 birds investigated through post mortem examination were positive for colibacillosis giving an overall prevalence of 79.07%. Out of 34 birds suspected with colibacillosis based on the result of postmortem examination, E. coli was isolated from 20 birds of which 15 and 11 samples were found to be positive for E. coli isolated from liver and cloacal swab samples, respectively. There were variation in occurrence of colibacillosis within some variables, such as age, flock size, use of antibiotics and poor hygienic management. A high frequency of colibacillosis was found in birds aged between 1 to 7 days. Occurrence of colibacillosis was varied according to flock size with the highest number of cases were recorded in the smallest farms having flock size 800 – 1000. The prevalence of colibacillosis varied proportionately according to using or not using antibiotics, although statistically not significant. This study reports the high prevalence of colibacillosis in commercial broiler chickens. Further investigation is required to identify the serotype of E. coli circulating in the commercial broiler chickens.