Situation of the chronic respiratory disease (CRD) on the broiler chicken flocks raised in households in several districts of Hai Phong city

Abstract

A total of 251 broiler chicken flocks raised in 53 households in several districts of Hai Phong city were investigated for the CRD from 6/2017 to 9/2018. The results of epidemiological investigation combined with diagnosis through symptoms, lesions and disease identification by PCR technique showed that
CRD appeared in 208/251 (82.9%) flocks of three chicken breeds raised in different raising house models in all households. There were 86.9% of the Ross 308 breed flocks infected with CRD, followed by the mix CP and ri hybird breed flocks with the infection rate was 74.5% and 65.7%, respectively. The CRD occurred in the ross 308 breed earliest from the 3 - 4 weeks old and the highest incidence in the 5 - 6 weeks old; the mix CP breed infected with CRD latter, starting from the 5 - 6 weeks old and the highest incidence was at the 7 - 8 weeks old. The chicken flocks raised in the closed-raising house model had a higher incidence in comparison with the chicken flocks raised in the semi-closed raising house model (P<0.05). The typical symptoms of the CRD chickens were rapid breathing, difficult breathing, cough, nasal secretions and thin body condition. The observed lesions included bleeding in the trachea and lungs, many gross lesions such as: sinusitis, conjunctivitis, tracheitis with yellow mucus in the trachea, thick air sacs containing casein, and pericardial sinuses containing water. In order to limit
the occurence of disease, farmers need to perform good hygiene and disease prevention, predict the disease outbreak times to take prevention, and it is necessary to have appropriate time to empty the
cage after each litter to limit disease transmission.