Among the disease conditions emerging in cage-free flocks, focal ulcerative dermatitis (FUDS) is responsible for losses of up to 30 percent between the emergence of the condition and depletion. Studies have shown that Staphylococcus aureus and S.agnetis were the predominant pathogens in affected flocks. Bacterial genera including Lactobacillus, Streptococcus, Fusobacterium present in the digestive tract were evaluated 16S PCR amplification and Whole-genome screening.
A research team affiliated with the Purina Animal Nutrition Center evaluated the beneficial effect of a direct fed microbial (DFM) combination against staphylococci regarded as the primary pathogens. A total of 68 confirmed Staphylococcus isolates were subjected to whole genome sequencing to determine the presence of antimicrobial resistance genes and virulence factors. The antimicrobial effect of four proprietary Bacillus combinations was evaluated in a screen to determine effective suppression of the pathogens in vitro. A specific Bacillus pumilus product comprising two selected and proven effective strains was developed that successfully reduced mortality and improved cumulative egg production in affected flocks.
Bacillus pumilus produces antimicrobial peptides including bacteriocins and amicoumacins that have antimicrobial and anti-inflammatory properties. These compounds have specific activity against methicillin-resistant S.aureus. The in vitro inhibition of the two staphylococci was reflected in a clinical response. Additional investigations are in progress to define the mechanism by which the direct fed microbial inhibits the pathogenesis of FUDS.
The direct fed microbial is commercially available as Purina FDP-12. Purina recommends inclusion of the DFM in the feed of flocks that demonstrate FUDS. The product should be considered as a preventive agent for flocks that are transferred to houses where a previous flock was affected by FUDS.
Ayala, D. I. (et al) Identification and characterization of the causative agents of focal ulcerative dermatitis in commercial laying hens. Frontiers in Veterinary Science. Doi. 10.3389/fvets.2023.1110573 (2023)