Prevention and Control of Infectious Coryza in Layer Hens

In experiment 0), the efficacy of -three comercial vaccinesCV 1, V 2 and V 3) were studied. VI is bivalent vaccine containedserotype A and C with thimerosal as killing agent andaluminum hydroxide as an adjuvant, V2 is trivalent vaccinecontained thimerosal as killing agent and saponine as anadjuvant while V3 is trivalent vaccine contained thimerosal askilling agent and mineral oil as an adjuvant. Serologicalfindings revealed that serotype A produced the higher antibodytiter followed by serotype C while serotype B produce the lowerantibody titers.The protection rate of the three vaccmes againsthomologous challenge were 100%.GMT increased post vaccination and another rise Inantibody titers were detected after challenge.In experiment (H) the efficacy of three commercialvaccines (V 11 V 2 and V 3) were studied under field conditions atthree By-Line flocks at one of the largest specializedcommercial layer farm at Sharkia Governorate.