Lack of Interference of Virginiamycin with Ileitis Immunisation

There was no evidence that the administration of virginiamycin in the feed reduced the efficacy of ileitis immunisation in this US study.
calendar icon 3 December 2013
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In Journal of Swine Health and Production, D.C. Beckler of Gut Bugs, Inc. and co-authors from Phibro Animal Health Corporation have published a paper on their experiment that aimed to determine if concurrent administration of the antibiotic, virginiamycin, interferes with immunisation efficacy of Enterisol Ileitis (Boehringer Ingelheim Vetmedica, Inc.).

They divided a total of 88 weaner pigs into four groups:

  • a strict negative, non-challenged, non-vaccinated, non-medicated group (NCC)
  • a challenged, non-vaccinated, non-medicated group (CC)
  • a challenged, vaccinated, non-medicated group (VC), and
  • a challenged, vaccinated, medicated group (VM).

The VM group received in-feed virginiamycin at 11g per tonne from day 0 (at four weeks of age) to day 27.

Vaccinated groups were immunised with one dose of Enterisol Ileitis on day 1. Virginiamycin administration continued for 28 days to determine whether it interfered with development of immunity generated by the vaccine.

Challenged groups were administered an oral dose of mucosal homogenate containing virulent Lawsonia intracellularis on day 31. Pigs were euthanised and necropsied on days 51 and 52 to evaluate intestinal lesions.

The researchers found significantly fewer macroscopic jejunal (P<0.01) and ileal (P<0.05) lesions in the VC and VM groups than in the CC group.

Microscopic ileal immunohistochemistry scores in VC and VM did not differ, and both were significantly lower (P<0.05) than the CC group.

During the vaccination phase when virginiamycin was administered, feed efficiency was best in VM (P<0.001) and intermediate in VC (P<0.001) than CC.

Beckler and co-authors concluded that, under the conditions of this study, administration of in-feed virginiamycin at 11g per tonne did not interfere with the efficacy of concurrent immunisation with Enterisol Ileitis.


Beckler D.C., M.U. Segal, D.L. Weiss R.D. Nimmo and D.J. Guggenbiller. 2013. Virginiamycin: Lack of interference with Lawsonia intracellularis immunization. J Swine Health Prod. 21(5):253–260.

Further Reading

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December 2013

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