Optimising infectious bronchitis vaccination for laying hens: Effect of regular revaccination and moult

Different vaccination protocols with two vaccine strains (VicS and A3) for infectious bronchitis (IB) virus were administered to Isa Brown laying hens during rearing and half the birds were revaccinated regularly during lay. At 57 wks of age, half of the birds were placed into an induced moult for a period of 5 weeks (moulted prior to revaccination), all birds were then revaccinated for IB and the other half of the birds moulted (moulted following revaccination). Production was lower in the birds that were revaccinated regularly during lay and the control (no vaccination until 14 weeks) and VicS eyedrop groups. Egg shell quality was better in the birds that were revaccinated prior to moult. Excreta moisture following revaccination was higher in the birds that had been revaccinated regularly during lay and in birds that were moulted after revaccination.