Field evaluation of piglet vaccination with a Mycoplasma hyopneumoniae bacterin as compared to a ready-to-use product including porcine circovirus 2 and M. hyopneumoniae in a conventional French farrow-to-finish farm

Abstract

Background: A controlled randomized trial was performed on a well-managed conventional French 180-sow farm. The trial compared the growth performances of piglets vaccinated at weaning (single shot) either with a commercial monovalent Mycoplasma hyopneumoniae bacterin vaccine or with a commercial bivalent vaccine (Porcilis® PCV M Hyo) against M. hyopneumoniae and porcine circovirus 2 (PCV2). The farm's porcine reproductive and respiratory syndrome status was stable, and most diseases (enzootic pneumonia, atrophic rhinitis, post-weaning multisystemic wasting syndrome) were controlled by routine vaccination.

Results: During the post-weaning phase, the growth performances of the piglets vaccinated with the bivalent vaccine were not significantly different from those vaccinated with the monovalent vaccine. However, during the fattening phase the group vaccinated with the bivalent vaccine had a significantly improved ADG (+34 g/d, p = 0. 047), resulting in a 5-day earlier shipment to slaughter. The group also had a shorter and lower PCV2 load in serum during the fattening period, and an improved lung lesions score. In both groups, three pigs died during the peak PCV2 viraemia (16-23 weeks of age). Immunohistochemistry of the lymph nodes showed that in the group vaccinated with the bivalent vaccine, none of these pigs had PCV2-like lesions, while 2 out of the 3 from the other group did. Results suggest that the added PCV2 valence in the vaccination protocol helps countering the negative impact of subclinical PCV2 infection on growth. The calculated return on investment of the added PCV2 vaccine valence was €1.7 extra revenue per slaughtered pig (€ 39 additional revenue per sow and per year), despite the fact that the cost of the bivalent vaccine was higher than the monovalent M. hyopneumoniae vaccine.

Conclusion: In this healthy conventional sow farm, the combined M. hyopneumoniae and PCV2 vaccination was efficacious, convenient to administer and profitable.

Keywords: Mycoplasma hyopneumoniae; PCV2; Randomized controlled field trial; Vaccine.

Fig. 1

Allocation of groups of pigs in fattening rooms, sorted by weight (three classes). *Animals of each pair (one in the MycPCV group and the other in the Myc group) were placed in adjoining pens. **The average pigs’ live-weight at the start of fattening is mentioned for each pen

Fig. 2

Whiskers plot of the distribution of ages at slaughter for the 70 pairs of pigs

Fig. 3

PCV2 serological profiles of the 12 pairs of pigs sampled during the trial. * p<0.05; ** p<0.01; *** p<0.001; **** One sample in the MycPCV group could not be analysed

Fig. 4

Average PCV2 genomic loads in serum of 12 pairs of pigs from both vaccination groups. (One sample in the MycPCV group could not be analysed)

Fig. 5

Immunohistochemistry results on lymph nodes of pigs dead during the fattening period (scale bars: A, 40 μm; B, 15 μm; C, 20 μm). a. Weakly PCV2-positive immunohistochemistry of a lymph node from a dead pig of the Mhyo group, whose pathology presented a marked granulomatous lymphadenitis, highly suggestive of PCV2-associated lesions. b. PCV2-positive (+ and ++) immunohistochemistry stains of a lymph node from a dead pig of the Mhyo group, whose pathology presented a moderate lymphadenitis, suggestive of PCV2-associated lesions. c. No obvious PCV2-positive IHC in a lymph node from a pig dead of gastric ulceration in of the Mhyo group

Fig. 6

Distribution of the lung lesion scores at slaughter in both trial groups