Effect of vaccination against Mycoplasma hyopneumoniae in pig herds with an all-in/all-out production system.

A multi-site field study was conducted to evaluate an inactivated Mycoplasma hyopneumoniae (Mh) vaccine in 14 pig herds infected by Mh and practising an all-in/all-out production system. In each herd, a vaccinated and control group of 250 pigs each were compared during the growing/finishing period with respect to performance parameters (major variables) and by means of clinical, serological and pathological parameters (ancillary variables). Mh vaccination significantly (P < 0.05) improved daily weight gain (+22 g), feed conversion ratio (-0.07), medication costs (-0.476 ECU/pig) (1 ECU = US$1.0269542), prevalence of pneumonia lesions (-14%) and severity of pneumonia lesions (-3%). Mortality rate, severity of coughing and carcass quality were not significantly influenced by Mh vaccination. Serological results of Mh and other respiratory pathogens are presented and discussed. A cost-benefit analysis based on significantly improved performance parameters demonstrated that Mh vaccination was economically attractive as it resulted in an increase of the net return to labour with 1.300 ECU per finishing pig sold. The sensitivity of the economic benefit was illustrated towards fluctuations in pig finishing prices.