IMMUNOLOGY, HEALTH, AND DISEASE Natural Humoral Immune Competence and Survival in Layers

ABSTRACT The relation between survival and levels of humoral components of innate (and specific) immune competence of laying hens was investigated in a popula-tion of 1,063 laying hens from 12 purebred layer lines. Natural immune competence of the chickens was studied by measuring levels of natural antibodies (NAb) binding to keyhole limpet hemocyanin (KLH) or lipopolysaccha-ride (LPS), respectively, and hemolytic (classical and al-ternative) complement activity at 20, 40, and 65 wk of age. In addition, levels of antibodies binding a Newcastle disease vaccine strain as a measure of specific immunity were investigated at 20 wk of age. A distinction could be made between lines showing high or low immune competence with respect to NAb, complement activity, and specific antibodies. Within lines, significant correla-tions were found for each of the innate parameters amon