Efficacy of tylosin phosphate for liver abscess control in feedlot cattle, by treatment duration: a Bayesian network meta-analysis supported by a randomized trial

BACKGROUND: Tylosin phosphate feed supplementation is the most common method used to control liver abscesses (LAs) in US feedlot cattle, but reducing antimicrobial exposures is critical. HYPOTHESIS/OBJECTIVES: We conducted a 2-phase study, using a randomized controlled trial designed to supplement a Bayesian network meta-analysis (NMA) to test bioequivalence of different durations of tylosin supplementation for the control of A+ LA's. ANIMALS: Sixteen thousand three hundred sixty-eight feedlot cattle. METHODS: A randomized controlled trial evaluated 4 treatment groups and was interpreted within an NMA. The treatment groups included no tylosin supplementation (negative control), tylosin supplemented throughout the finishing period (Continuous), withdrawing tylosin 84 d before harvest (-84WD), or 56 d before harvest (-56WD). A total of 16 728 animals were randomly allocated in a 1:1:2:2 ratio, respectively. Thirty-two controlled studies with 72 086 enrolled animals, featuring 10 interventions, were incorporated into the NMA. RESULTS: Continuous cattle had reduced odds of severe (A+) LAs compared to NC cattle in the randomized trial (odds ratio = 0.75; 95% CI, 0.51-1.11). The NMA suggested tylosin use was superior in reducing LAs when compared to untreated cattle. However, early withdrawal did not have equivalent efficacy compared to continuous use. CONCLUSIONS AND CLINICAL IMPORTANCE: This investigation successfully merged a systematic review, NMA, and a primary trial to optimize fiscal and animal resources in a major research investigation.