Beneficial impact of vaccination with a PCV2 vaccine and a Mycoplasma hyopneumoniae bacterin in piglets under French field conditions

PCV2 and Mycoplasma hyopneumoniae (M hyo) are the etiologic agents of PCV2-Diseases (PCVD) and enzootic pneumonia (EP), respectively. They are both known to play an important role in porcine respiratory disease complex (PRDC). The objective of this study was top evaluate the benefit of adding a PCV2 vaccination to a regular M hyo vaccination on standard production performance and EP lung lesions.

The trial was conducted in a PRRSv-negative farrow-to-finish farm located in France. Piglets used not be vaccinated against PCV2. They were weaned at 4 weeks of age and kept in a continuous flow nursery and 2 fattening units. All pigs were sent to slaughter at a target bodyweight of 120 kg so an increased slaughter age was the consequence of sub-optimal growth performance and lack of homogeneity. Piglets of two batches (approximately 1200 piglets) were randomly allocated to two experimental groups equally balanced according to batch, sex and weight. At weaning, one group was injected with CIRCOVAC® (Merial), 0.5 mL, IM and a M hyo vaccine, 2.0 mL, IM in two separated loci with a double-barrel syringe while the other group only received the M hyo vaccine. Group-based bodyweights were recorded at weaning, age and carcass weights were individually recorded at slaughter. Lung scores (Madec’s grid) were recorded in approximately 180 pigs in each group according to the same sampling schedule. Statistical analysis were performed using ANOVA, Wilcoxon test, F-test or Fisher’s exact test depending on the parameter. Growth parameters were analyzed only in the first batch as the lightest pigs were sold before slaughter in the second batch.

No adverse reaction was observed after any of the vaccinations. Mortality rate remained low i.e. 1-2.5% in post-weaning and 3-5 % in fattening depending on the batch. Pigs vaccinated with CIRCOVAC were slaughtered 2.7 days earlier (p< 0.01) and growth was significantly improved by 19g/day (p< 0.01). It yielded also a significant reduction of pigs sent to slaughter older than 182 days (p< 0.01), thus confirming the significantly better homogeneity (p< 0.01). Lung lesion scores were significantly improved in CIRCOVAC-vaccinated pigs with: a significant increase of non-damaged lung proportion (p< 0.01), a definite reduction of the median lung score (p< 0.01) and a dramatic reduction of severe pneumonia (p< 0.01), indicating a better control of M hyo.

CIRCOVAC vaccination in addition to the M hyo vaccination helped in the control of subclinical PCVD and EP and improved the weaning-toslautghter growth performance of the pigs

Disclosure of Interest: B. Delhaye: None Declared, B. Boivent Conflict with: MERIAL S.A.S., G. Perreul Conflict with: MERIAL S.A.S., J.-B. Hérin Conflict with: MERIAL S.A.S., O. Merdy Conflict with: MERIAL S.A.S., F. Joisel Conflict with: MERIAL S.A.S.