During unprofitable market situations it is particularly questioned whether the benefits of vaccination justify the costs.

On a French farrow-to-finish farm with 170 sows an efficacy study was carried out for a single-shot Mycoplasma hyopneumoniae (M. hyo) depot vaccine. From the results, the economics of vaccination wereanalysed. Using a stepwise reduction/ increase procedure for slaughter prices and feed costs the effect of varying market situations could be included.

On the farm, respiratory disorders had been observed, including coughing for several months, and the presence of M. hyo was confirmed by antigen immunofluorescence. Three successive batches of pigs wereincluded in the study. Each batch was randomly divided into vaccination and control group and housedin the same room in pens of 12 to 14 pigs and fed liquid feed. The piglets were vaccinated before introduction into the fattening unit (10 weeks of age) with a single dose of 2ml Ingelvac?M. hyo. The control group received 2 ml isotonic saline solution by intramuscular injection. All finishers were sold as a batch without any weight selection. The trial farm was exceptionally well managed with an excellent average performance level.

The increased prevalence of serum antibodies towards the end of the fattening period, both in the vaccination and control group, suggests that the natural challenge with M. hyo took place in the middle of the growing period (Figure 1).

Figure 1: Sero-conversion in the control and vaccination group during the growing period