THE EFFECT OF STRESS ON THE RESPONSE OF CHICKENS TO COCCIDIOSIS VACCINATION

Six-week-old Leghorn chickens, which had been adapted to both their en vironment and cage mates, were orally inoculated with 400 Eimeria tene lla oocysts as a means of low-dose vaccination. At 2, 3, 4, 5 or 6 day s after vaccine administration, the birds were subject to 24 h of soci al stress through a prescribed method of random redistribution. Two we eks after vaccine administration, the birds were challenged by oral in oculation with 8000 oocysts. Caecal lesion scores were determined 6 da ys after challenge. Vaccinated chickens were more resistant to lesion formation than unvaccinated controls, and protection, as determined by lower lesion scores, was significantly enhanced when stress in the fo rm of social disruption was applied on the fourth day following vaccin e administration. (C) 1997 Elsevier Science B.V.