The effect of cold stress on the pathogenesis of necrotic enteritis in broiler chicks

Cold stress is a physical environmental stressor with significant effect on the poultry industry. The aim of the present study was to investigate the effect of cold stress as a predisposing factor for necrotic enteritis in broiler chicks. The experimental challenge model included an oral inoculation with 10-fold dose of attenuated anticoccidial vaccine and multiple oral inoculations with a specific strain of Clostridium perfringens. Birds were either challenged or not as described above, and either exposed or not to repeated cold stress (15 degrees C for 12h/day for 4 days). From each bird, intestinal gross lesions were scored and intestinal digesta pH and viscosity were measured. C. perfringens was counted in the caecum. The statistical analysis and evaluation of the experimental data revealed that the cold stress in challenged birds significantly increased the incidence and the severity of necrotic enteritis lesions (?0.05), while causing no lesions in unchallenged birds. Moreover, the cold stress caused a significant increase (?0.05) in the pH and C. perfringens counts in the caeca. The study provides evidence that cold stress increased the susceptibility to necrotic enteritis in a subclinical experimental model and thus should be regarded as a physical environmental stressor that could significantly affect the welfare, health and intestinal ecosystem of broiler chicks.