Microbiome characterization and identification of potential causative agents of tail necrosis in pigs

    

Tail docking of pigs is banned in many countries based on animal welfare concerns. An unintended consequence of the ban can result in the loss of tail integrity from bacterial pathogens causing inflammation, lesions, and necrosis which impacts pig welfare and results in significant monetary losses. Tail docking is used in many countries as a preventive measure; however, in these countries, an intact tail is a desirable trait in pigs and can increase value in certain markets. This study aimed to use 16S microbiome for the characterization of the microbial community of inflamed and necrotic tails and compare those to the microbial communities of healthy tails. A total of 60 rectal swabs and 60 tail (20 necrotic, 20 inflamed, 20 healthy) samples were used in this study for 16S microbiome analysis and bacterial isolation. A corresponding duplicate set of samples was taken for bacterial isolation. Linear discriminant analysis of the microbiome identified Fusobacterium necrophorum, Streptococcus dysgalactiae, and Staphylococcus hyicus as the potential causative agents of tail necrosis due to their increased relative abundance in sick versus healthy animals. These pathogens were found in trace amounts in fecal samples of the healthy pigs, and in significantly higher abundance in the samples from affected pigs. These results were confirmed by plating, with Streptococcus dysgalactiae and Staphylococcus hyicus being isolated exclusively from fecal samples, and samples from inflamed and necrotic tails from the sick animals group. A total of 20 proprietary direct-fed microbials (DFM) were evaluated for their antimicrobial properties against the isolated pathogens by using a combination of agar welldiffusion (AWD) and competitive exclusion (CE) screenings. The most inhibitory DFM strains were used to develop a customized DFM product that is being used at swine facilities with cases of tail inflammation and necrosis. The results of this study suggest a potential translocation of these pathogens from the gut to the dermis, resulting in inflammation and tail lesions.

Key Words: Tail necrosis, swine, gut health, translocation, DFMs.