Vaccination against pleuropneumonia – a field trial with two different vaccines in one herd infected with Actinobacillus pleuropneumoniae serotype 2

Pleuropneumonia caused by Actinobacillus pleuropneumoniae (Ap) results in significant losses in the pig industry worldwide. Besides acute outbreaks of respiratory disease, deaths, increased antibiotic usage, condemned carcasses and lower animal welfare, there are also subclinical manifestations in an infected herd. The consequences may be a lower average daily weight gain (ADG), a higher feed conversion rate (FCR) and a high level of chronic pleurisy.

The aim of this study was to evaluate the effect of vaccination against Ap serotype 2 on FCR and the potential economic benefit of using vaccination to control both the subclinical and clinical manifestations of the disease.

In a 500-sow full-line production herd with a history of Ap-related clinical symptoms and mortality among finishers, a high FCR and a high level of chronic pleurisy, pigs were vaccinated at the age of ten to eleven weeks on arrival at the finisher sections and again three to four weeks later with either Porcilis ® APP or Hyobac APP2. The respective groups, including a control group of non-vaccinated pigs, were randomly separated into pens of 40 pigs sharing the same feed pipe. The number of pens included in the trial was 24 for each vaccine and 36 for the control group. Control pigs were bled twice (three weeks after arrival, and shortly before slaughter) to assess the serological status of Ap 2 in the batch (section). Throughout the finisher period, the use of antibiotics, number of deaths, ADG and FCR were recorded. At slaughter, a subset of lungs were sampled and sent to the Laboratory for Swine diseases in Kjellerup to investigate the prevalence and extent of Ap-related lung lesions in each group

No differences were seen between the two vaccine groups and the control group in FCR, ADG, mortality, antibiotic treatments or lung lesions. During the study, no treatments for respiratory diseases were performed, and the mortality was lower than before. Furthermore, in some of the batches, the time of seroconversion occured earlier. Therefore, the vaccination time might have been too late.

In this study, we found no effect of vaccination against Ap, probably because the vaccination was performed too late to achieve maximum protection from the vaccines

Disclosure of Interest: None Declared.