Investigation into the effect of in-feed flavophospholipol on Salmonella shedding and antimicrobial resistance in pigs

Abstract

The objectives of this study were to investigate the time course of Salmonella shedding and antibody response, as well as determine the impact of in-feed flavophospholipol in reducing Salmonella and antimicrobial resistance in grower-finisher pigs. Over 10 weeks, 45 Salmonella-infected pigs either received feed containing 4 ppm of flavophospholipol or non-medicated diet. Weekly fecal samples, and tissue samples at slaughter were cultured for Salmonella and generic E. coli. A subset of the isolates were tested for antimicrobial susceptibility. In addition, pigs were tested for Salmonella antibodies multiple times. Data were analyzed using a multilevel mixed effects logistic regression model. Flavophospholipol had no impact in reducing Salmonella shedding; however, antimicrobial resistance in E. coli was decreased. Salmonella shedding decreased from 12 to 20 weeks of age (P<0.05) during which antibody response increased (P<0.05). Eight different Salmonella serotypes were isolated with pigs being reinfected with different serotypes. At slaughter, Salmonella was isolated from some pigs that had not tested positive on weekly fecal checks for ≥ 7 weeks indicating that the absence of Salmonella in fecal samples may not be indicative of the carcass being Salmonella-free.