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 Mycoplasm a 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 w ith respect to performance parameters (major variables) and by means of cli nical serological and pathological parameters (ancillary variables). Mh vac cination significantly (P < 0.05) improved daily weight gain (+22 g), feed conversion ratio (-0.07), medication costs (-0.476 ECU/pig) (1 ECU = US$1.0 269542), prevalence of pneumonia lesions (-14%) and severity of pneumonia l esions (-3%). Mortality rate, severity of coughing and carcass quality were not significantly influenced by Mh vaccination. Serological results of Mb and other respiratory pathogens are presented and discussed. A cost-benefit analysis based on significantly improved performance parameters demonstrat ed that Mb vaccination was economically attractive as it resulted in an inc rease of the net return to labour with 1.300 ECU per finishing pig sold. Th e sensitivity of the economic benefit was illustrated towards fluctuations in pig finishing prices. (C) 1999 Elsevier Science Ltd. All rights reserved .