Post-vaccination evaluation of an erysipelas/parvovirus bivalent vaccine administered to sows during lactation on follicular development and piglet growth.

Vaccines against Erysipelothrix rhusiopathiae (ER) and porcine parvovirus (PPV) are employed in sow farms worldwide. This study evaluated the impact of administering a bivalent ER/PPV vaccine during lactation. Multiparous sows (n = 83) of two different farms (A (herd size 900 sows) and B (1000 sows)) were allocated in two different groups: 1) sows inoculated with saline solution (non-vaccinated group); 2) sows inoculated with the bivalent vaccine against ER/PPV (vaccinated group). The injections were administered at ∼11 days of lactation. The study was conducted in four different experiments: the first experiment, evaluating the female genital tract (uterus and ovary) and follicle development, was performed in culled sows (n = 19) of Farm A the day after weaning (∼24 days). The remaining experiments, which examined internal temperature, offspring growth, and sow feed intake, were conducted at Farm B (n = 64). The results of follicle populations, showed a greater frequency of large follicles in non-vaccinated compared to vaccinated sows was observed (p < 0.001). The final weight of the piglets and their weight gain were higher in the non-vaccinated group (p ≤ 0.05). A statistical trend was also observed in the average weight gain of piglets. No differences were observed regarding sow´s rectal temperature between groups around the period of injection but the vaccinated group consumed less sow feed on the day of injection (p = 0.016). In conclusion, the administration of this vaccine against ER/PPV during the lactation period had a negative impact on follicle development, sow feed intake, and offspring weight gain and final weight.