Efficacy of Porcilis PRRS - field trial Greece

Method

1. Every alternate week groups of about 1250 six week old piglets were vaccinated with Porcilis PRRS.
2. Every other week groups of about 1250 pigs were left unvaccinated as control animals.
3. From each group of 1250 pigs, 40 pigs were monitored for:
• growth performance
• clinical signs
• medication requirements
• mortality
4. After 16 weeks approximately 10 000 pigs had been vaccinated with Porcilis PRRS and approximately 10 000 control pigs had been left unvaccinated.

Results and conclusion

Vaccine safety

Vaccination did not cause any local or systemic reactions and no growth retardation was noted.

Vaccine efficacy

Vaccination with Porcilis PRRS resulted in:

• Outbreaks of respiratory disease was reduced from 8 groups (control pigs) to 2 groups (vaccinated pigs).See Table 1.
• The mortality rate in the vaccinated pigs was half that of the control pigs.See Table 1.
• At slaughter fewer bacteria were present in the lungs of vaccinated pigs than in the lungs of the unvaccinated pigs.
• An average increase in the absolute slaughter weights of 6.1 kg per pig.
• An overall increase in the average daily growth rate of 43 g per pig per day. See Table 2.
• 8.5% more efficient feed conversion. See Table 2.

Table 1. Results-Outbreaks of respiratory disease and mortality

Observation period (weeks)	Respiratory Diseases (# affected batched)		Mortality (%)
	Control	Vaccinated	Control	Vaccinated
3.5-1.7	0	0	2.37	2.47
8-17	5	0	3.58	0.88
18-23	3	2	1.74	0.09
TOTAL 3.5-23	8	2	7.5*	3.44*

*(Mavromatis, J. 1989)

Table 2. Results: daily gain and feed conversion

Group	Daily weight gain (g)	Feed conversion
Vaccinated	645±48	2.45±0.13
Controls	602±44	2.66±0.09