Several trials in Kansas have demonstrated that circovirus vaccination improves the performance of growing pigs even on high health farms.
On a 300 sow, PRRS negative farm with a history of PCVAD, 235 animals were vaccinated with a porcine circovirus type 2 (PCV2) vaccine at three and six weeks of age. They were housed in the same pens as 250 control (non-vaccinated) animals. Mortality rate and growth rate were significantly better in vaccinated pigs. In the wean to finish stage, the mortality rate was 18.1% in the controls and 7.7% in the vaccinates. The ADG was 705 gm in the controls and 755 gm in the vaccinates. All animals were marketed on the same day and the vaccinates were 8.6 kg heavier on average.
In two research barn trials, 1300 PRRS positive pigs were vaccinated at nine and eleven weeks of age and 1253 PRRS positive pigs were vaccinated at five and seven weeks of age. The vaccinates and controls were housed in separate pens. The economic benefits of vaccination on mortality rate, ADG and feed efficiency improvements were calculated at a 2:1 return in the first trial and a 4:1 return in the second trial.
Another trial with 1470 pigs on a PRRS, Mycoplasma and App-positive farm compared vaccination with a one dose product and vaccination with a two dose product against unvaccinated controls. All pigs were commingled in the same pens. There was no significant difference in mortality rates between control animals and vaccinates, but growth rates were significantly better in both vaccinated groups. There was no significant difference in ADG between the vaccinated groups.
The last trial compared the effect of PCV2 vaccination and genetic line on mortality in a high health (PRRS and Mycoplasma-negative) 1700 sow herd. The primary clinical signs of PCV2 infection on this farm were ill-thrift and stunting, not mortality. The two genetic lines were a Duroc-based line and a synthetic (Pietrain/Duroc/Large White) line. Piglets were vaccinated at weaning and three weeks later and controls were commingled with vaccinates. There was no significant difference in mortality between vaccinates and controls, but there was a significant difference in the response of the genetic lines in terms of growth rate. Vaccinated pigs were heavier in both lines, but, in the Durocs, the vaccinated pigs were 20 lbs. heavier than the controls, whereas in the synthetic line pigs, the vaccinates were only 5 lbs. heavier than the controls.
In summary, in all of the trials, circovirus vaccination provided statistically significant benefits in growth rate, irrespective of the disease status on the farms. These results indicate that, even on farms where circovirus is not clinically apparent, PCV2 vaccination may be a cost-effective procedure.
This information was presented by Dr. Steve Dritz at the Shakespeare Swine Seminar on November 28, 2007
By Janet Alsop - Vet Disease Prevention - Swine - Veterinary Services