Clinical observation, pathology, and serum biochemical changes in infectious stunting syndrome of broiler chickens

Abstract

This research was conducted to study the clinical signs, post-mortem, histological lesions, and biochemical changes of serum parameters in both field and experimental induction of infectious stunting syndrome (ISS). For this study, eight suspected broiler chicken flocks were investigated. For transmission studies, inocula were prepared from three flocks with known ISS lesions. Fifty-six-day-old broiler chicks were randomly divided into control and treatment groups. In treatment groups, 44-day-old chicks were inoculated with 1.5 ml of prepared inocula. The control groups (12 chicks) were inoculated with the same volume of normal saline. At 14 days of age, the chicks inoculated with whole intestinal homogenate showed 42.7% lower body weights, and the chicks inoculated with bacterial-free intestinal homogenate showed 35.83% lower body weights compared with the control group (P < 0.05). The intestinal histopathologic changes of the stunted chicks were villous atrophy and mild-to-marked distention of crypts of Lieberkuhn. Histological examinations of the enlarged proventriculi revealed lymphocytic infiltration and dilatation of the glandular acini. Pancreatic lesions were degeneration, vacuolation, loss of zymogen granules of acinar cells, and fibrosis. The stunted chicks also showed an apoptosis process and virus-like particles in the enterocytes and macrophages. The blood serum biochemical analysis showed significant increases in alkaline phosphatase and amylase of the stunted chicks (P < 0.05) compared to the non-stunted chicks. The results of this research showed that broiler chicken farms with poor growth might be associated with ISS agents in Iran.