Evaluation of a Bacillus-Based Direct-Fed Microbial on Broiler Performance and House Fly (Musca domestica) Control

This study evaluated the effects of a Bacillus-based direct-fed microbial on broiler performance, excreta properties, and the impact on the survival of house fly larvae. A completely randomized design was used comprising two dietary treatments: (1) basal standard broiler diet (CON) and (2) CON + Amnil® at 500 PPM (AMN). Each treatment consisted of 48 replicate cage pens, each containing six male chicks, and were raised until 23 d of age. The average body weight (BW), feed consumption (FC), and feed conversion ratio (FCR) were measured weekly. On d21, blood was collected via the brachial vein for the measurement of corticosterone (CORT) concentrations and heterophil/lymphocyte ratio (H/L). Poultry excreta was collected three times on d14, d18, and d23. Excreta properties were evaluated using proximate analysis. For fly assessment, two assays were conducted: (1) oviposition and (2) fly larval development. For oviposition, adult house flies were provided with a choice between excreta from chicks fed with and without Amnil. For fly larval development, 100 fly larvae (<12 h old) were fed either control excreta or excreta from birds fed Amnil. The data were subjected to ANOVA to determine the treatment differences. BW was higher (p = 0.05) in the AMN group on d 14, but no other differences were found at any other time points. Additionally, BW-adjusted feed conversion ratio was improved (p = 0.046) in the AMN group. Excreta from the AMN group had lower (p < 0.05) moisture, pH, Zinc, Neutral Detergent Fiber, and Acid Detergent Fiber on d18 and lower (p < 0.05) pH and Zn on d 23. No statistical differences (p > 0.05) were observed in the CORT and H/L ratios. There were no differences (p > 0.05) between treatments for preference in oviposition. However, flies showed a significant preference for colonizing bird excreta at d23 than at d14 or d18, regardless of Amnil use. For the development experiment, a reduction (p < 0.001) of 32.2% in resulting pupal survival was observed when excreta from birds fed AMN compared to the control. In conclusion, AMN supplementation improved cumulative FCR and modified the properties of excreta, resulting in the disturbance of normal oviposition and reduction in the survival of fly larvae compared to the CON group.