The effect of a metaphylactic pulse dosing in-feed antimicrobial strategy on finishing pig health and performance

Don Walter, DVM; J. Tyler Holck DVM, MS, MBA; Steve Sornsen, DVM, MS; Chad Hagen, PhD; Isabel Turney Harris, DVM, PhD

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Purpose: To compare the effect of metaphylactic pulsedosing with either a continuous-feed antimicrobial medicationstrategy or no feed medication on finishing pig health and performance.

Methods: Barrows (n = 1092) from a herd naturally infectedwith endemic respiratory pathogens were assigned by pen to oneof three treatment groups: a "Continuous" group thatreceived alternating doses of tiamulin plus chlortetracyclineon weeks 2,4,7,10, and 13 interspersed with a reduced concentrationof chlortetracycline alone during weeks 3,5,6,8,9,11, and 12;a "Pulse" group, which received in-feed pulse dosingwith tiamulin plus chlortetracycline only in weeks 2,4,7,10, and13 with no medication during the other study weeks; or nonmedicatedControls that received nonmedicated feed throughout the trial.Growth performance, survivability, and seroconversion to variouspathogens were measured.

Results: Both metaphylactic Pulse and Continuous medicationstrategies improved growth rate, feed intake, feed conversionefficiency, and survivability in the presence of naturally occurringmycoplasmal and viral (swine influenza virus, porcine reproductiveand respiratory syndrome virus) respiratory disease compared toControls. Pulse but not Continuous medication permitted sufficientnatural exposure to Mycoplasma hyopneumoniae to stimulateactive humoral immunity.

Implications: Both feed medication strategies significantlyimproved performance versus nonmedicated controls. Metaphylacticpulse dosing with appropriate antimicrobials may improve growthperformance while permitting exposure to and stimulation of activeimmunity against endemic mycoplasmal pneumonia.

Keywords: pulse dosing, metaphylaxis, antibiotic, feed medication, tiamulin, chlortetracycline, serology, Mycoplasma hyopneumoniae

RIS citationCite as: Walter D, Holck JT, Sornsen S et al. The effect of a metaphylactic pulse dosing in-feed antimicrobial strategy on finishing pig health and performance. J Swine Health Prod 2000;8(2):65-71.

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