“Weaner vaccination does not lower antibiotic use”

That was the conclusion of research on the situation in Denmark, presented by Caroline Temtem, attached to the University of Lisbon, Portugal. She presented her research in Denmark at the International Pig Veterinary Society (IPVS) Congress, this year held in Dublin, Ireland.

Opposite hypothesis

The Danish research that Temtem was involved with, actually aimed to research the contrary. She explained during her talk “that it was hypothesised that herds with increased use of vaccination would have a lower antimicrobial use than herds not using vaccination”.

She added, “But what we found was exactly the opposite.”

In total over swine 1,500 herds

The research group to which Temtem belonged set up a research model in which farms were classified according to different vaccination strategies for three pathogens. All one-site system pig herds active in 2013, having more than 50 sows and 200 weaners were selected for the study. In total, 1,513 herds were selected.

• No vaccination (380 farms)
• Porcine Circovirus 2 (PCV2) only (290 farms)
• Mycoplasma hyopneumoniae (M. hyo) only (221 farms)
• Lawsonia intracellularis (L. intracellularis) only (21 farms)
• PCV2 + M. hyo (507 farms)
• PCV2 + L. intracellularis (35 farms)
• M. hyo + L. intracellularis (11 farms)
• All 3 vaccination regimes (41 farms)

Temtem’s presentation outlined how, in total 1,415 herds had antimicrobials prescribed for gastro-intestinal disorders, and 836 for respiratory disorders.

PCV2 vaccination

In the congress abstract book, she wrote, “Herds using PCV2 vaccination had higher antimicrobial consumption overall, and with gastro-intestinal indication, than herds not using the vaccine.”

She continued, “Herds using M. hyo vaccination had higher antimicrobial consumption in general, and with respiratory indication, than herds not using the vaccine.”

Combination of vaccines

“Concerning PCV2 and M. hyo vaccination, the same tendency of results were observed in multivariable analyses.”

She concluded, “Herds using L. intracellularis vaccination had a lower antimicrobial consumption with respiratory indication, compared to the herds that did not use the vaccine. This suggested that antimicrobials could have been used for other disease categories than those officially prescribed by veterinarians. These results were no longer statistically significant in the multivariable analyses.”

She concluded, “In general, pig herds using vaccines against M. hyo and PCV2 (and sometimes L. intracellularis) had a higher antimicrobial consumption in the weaner section compared to those not using vaccination at all.” Or, in other words, she said, “Herds applying routine vaccination had a higher use of antimicrobials compared to herds not using the vaccines.”

Explanations for outcomes

She did wonder how the outcome could be explained. She suggested that probably this is a result of health problems existing in the herd prior to the initiation of vaccination or concurrent disease.

Coincidentally, the speaker following her, Prof Jeroen Dewulf, Ghent University, Belgium, could confirm this tendency, having come across similar results in his research. He suggested that perhaps the outcome that high vaccination use correlates with high antibiotics use might not be related to biological aspects, but might all be related to ‘the psychology of farmers’.

Temtem’s outcome is doubly remarkable as she is an exchange student, for whom an exception was made to give an oral presentation. Most presenters at the congress are researchers.

Apart from Temtem, the research was done by Lis Alban, Danish Agriculture & Food Council; Ken Steen Pedersen and Amanda Brinch Kruse, University of Copenhagen, Denmark.