Etiological and histomorphological studies on early chick mortality in broiler chicken in Kashmir, India.

Background: Early chick mortality (ECM) is one of the most important problems of the poultry industry that causes severe economic losses to the farmers. The chick mortality varies in different geographical locations and its etiological factor also varies.

Aim: The aim of the present work was to isolate and identify various etiological agents responsible for causing ECM in broilers, and study the overall occurrence and pathology of various disease conditions responsible for causing ECM in broilers.

Methods: The study included clinical and laboratory investigations vis-a-vis ECM. A total of 2,346 broiler chickens under the age group of 2 weeks from around 87 outbreaks were necropsied and examined for the presence of lesions corresponding to different disease conditions. Representative samples (heart, liver, intestine, lung, and spleen) were collected in a sterile Petri dish for bacterial and fungal isolation and stored at 4°C till inoculation in nutrient broth, followed by a collection of tissue samples (heart, liver, lung, spleen, intestines, and kidney) in 10% buffered formalin for histopathological examination.

Results: The overall mortality in the flocks was 1.7%, with 1.6% mortality in the first week and 1.8% in the second week of life. Colibacillosis was responsible for causing the highest ECM of 2.01% followed by salmonellosis (1.9%), aspergillosis (0.9%), and gout (0.6%). The case prevalence of colibacillosis, salmonellosis, aspergillosis, and gout was seen as 58.1%, 32.3%, 6.4%, and 3.2%, respectively. Colibacillosis (2.1%), salmonellosis (3.2%), and gout (1.7%) were responsible for causing higher mortality (3.2%) in the second week of life of broilers, aspergillosis in the first week (1.0%) and gout caused similar percentage of mortalities in the first and second week of life. Microscopic changes were predominately characterized by congestion, hemorrhage, infiltration by various inflammatory cells especially heterophils, the focal granulomatous reaction in aspergillosis, and urates in the tubular parenchyma in the form of pink amorphous radiating material surrounded by a narrow zone of inflammatory cells in cases of visceral gout.

Conclusion: Salmonellosis, colibacillosis, aspergillosis, and gout were diseases mainly responsible for ECM in broilers. Colibacillosis was responsible for causing the highest ECM followed by aspergillosis, salmonellosis, and gout.