EFFECTS OF STRAIN, CAGE DENSITY AND POSITION ON IMMUNE RESPONSE TO VACCINES AND BLOOD PARAMETERS IN LAYER PULLETS

Abstract

Two thousand 1-day-old layer chicks were used in the study from Lohman Brown, Isa Brown, Lohman White and Bowans White breeds. The chicks were placed in the at 3 cage densities (211.8, 274.5 and 370.6 cm2 per bird) and on 3 positions (as top, middle and bottom tiers). All birds were kept under standard management policy and a commercial vaccination program was practiced. Total specific antibody titres to Infectious Brochitis Virus (IBV), Infectious Bursal Desease Virus (IBDV), Newcastle Disease Virus (NDV) and Egg Drop Syndrome Virus (EDSV) vaccines at the ages of 5, 10 and 20 weeks were serologically determined by ELISA. Cellmediated immune response was also evaluated. In commercial white egg laying strains specific antibody titres to IBV, IBDV, NDV and EDSV vaccines were greater than in Brown egg layer strains. Keeping in cage created more stress in Brown egg laying chicks than those in white egg laying chicks. As cage density increased, the ratio of heterophils to lymphocytes (H/L ratio) slightly increased. Cage position had no influence on the titres of antibodies to IBV and IBDV vaccines but the position of cage in pullets where chicks were stocked, from top to bottom, NDV and EDSV antibody titre decreased and percentage of heterophils, H/L ratio and basophil rates were low. These findings suggest that cage-related stress could be decreased, resistance to diseases and finally well-being of hens may be improved if hens are kept under proper position and density within cage systems with respect to their physiological and behavioral characteristics that controlled by genes.

Keywords

• cage density
• cage position
• pullet
• strain
• stress
• welfare