Challenge models are needed to understand the pathogenesis of Necrotic Enteritis (NE) and provide the basis of evaluating non-antibiotic feed-additive interventions. In the category of non-antibiotic feed additives, the application of probiotics to improve intestinal health and growth performance of broiler chickens in the face of a NE challenge have been well described. However, it is crucial to evaluate the consistency of specific probiotics on mitigating the disease challenge and improving performance. Therefore, a meta-analysis of 5 independent research trials was conducted with the objective of evaluating the effect of Bacillus subtilis DSM 32315 (probiotic) on body weight gain (BWG), feed conversion ratio (FCR), NE mortality, and lesion scores (LS) of broiler chickens challenged with NE. These independent studies were conducted in 3 different countries (U.S., Thailand, and Finland). The statistical analysis utilized fixed and random effects to estimate the mean effect size (MES) of the difference between NE challenged birds (control) and NE challenged probiotic-fed birds and the 95% confidence interval (CI) of MES. A meta-regression was performed to evaluate heterogeneity (MES variance) among studies. The statistical analysis was performed using the robust variance estimation strategy by a SAS Macro. Probiotic supplemented birds had a significantly higher BWG (MES= 1.04, p= 0.009), a significantly lower FCR (MES= -1.39, p= 0.020), NE mortality (MES= -1.15, p= 0.012), and LS (MES= -1.29, p= 0.045). Response variables of BWG (Q= 2.81; p= 0.560) and NE mortality (Q= 5.60; p= 0.354) did not present heterogeneity. Heterogeneity was found on FCR (Q= 10.34, p=0.035) and LS (Q=16.13, p= 0.001). Overall, dietary supplementation of Bacillus subtilis DSM 32315 significantly improved BWG and reduced FCR, mortality, and LS in a repeatable large-scale manner.

This content is only available as a PDF.
You do not currently have access to this content.