476 Alternatives to Antibiotics to Control Acidosis and Liver Abscesses in Cattle

Abstract Beef has served as a major protein source in human nutrition. Over the last 25 years, global beef production has increased exponentially. With the projection of global demand for meat and milk to double by 2050, beef production is expected to increase to meet future demands. This change in production scale has resulted in intensification in production systems. As a consequence, the need for better animal health, disease control, and “health management” has led to the increased use of antibiotics in the beef cattle production system. This increased use of antibiotics (especially for metaphylactic use and as growth promotants) have led to the increase in the microbial population that is resistant to antibiotics and the AMR gene pool within the beef cattle production system. As such, novel strategies to reduce antimicrobial use while improving animal health and efficiency is critical. One such alternative strategy is the use of probiotic strains of bacteria to help improve animal health replacing antibiotics. In the current study we isolated several species of bacteria from the rumen where each microbial species has the ability to control the growth of acidosis forming Streptococcus bovis and liver abscess forming Fusobacterium necrophorum populations in cattle. The microbial species were isolated from rumen contents of beef cattle fed a distillers grain plus solubles diet. The isolates were screened for its ability to inhibit Streptococcus bovis and Fusobacterium necrophorum using live cultures and the resulting positive cultures were characterized by 16S rRNA sequencing. The resulting positive isolates were grown and the cell extracts, live lyophilized cells and heat killed cells were used for disk diffusion assays that revealed the inhibition of both Streptococcus bovis and Fusobacterium necrophorum by each isolate. Two of these strains are GRAS approved and will be used for in-vivo experiments in early 2018. In addition, the genome sequencing of the strains are underway to identify the mode of inhibition. This study demonstrates the potential of using probiotics as an alternative to antibiotics to control acidosis and liver abscesses.