PARENTAL EFFECT ON THE HUMORAL IMMUNE-RESPONSE TO ESCHERICHIA-COLI AND NEWCASTLE-DISEASE VIRUS IN YOUNG BROILER CHICKS

Genetic and environmental variables influence animal resistance to dis ease infection. In addition, maternal effects were also found in studi es with egg-type chicken lines. In our laboratory, meat-type chicken l ines were divergently selected for either early or late maturation of the immune system, based on family and individual antibody responsiven ess at 10 d of age. The high-antibody (HC) and low-antibody (LC) lines differed significantly in the early immune response to Escherichia co li, to Newcastle disease virus (NDV) vaccination, and to several other immune functions. Reciprocal crosses between the HC and LC lines were performed over 2 yr at three different locations. Immune responses to E. coli and NDV vaccination provided separate estimates of maternal a nd paternal effects. Dam effect on immune response to E. coli vaccine was significantly larger than sire effect; the antibody titer in both reciprocal crosses was intermediate between the parental lines, but th e mean titer of the HC x LC cross was significantly lower than that of the LC x HC cross. Similar, but not significant, ranking of crosses w as observed for the response to NDV. Evidently, the level of the offsp ring humoral immune response was more a dam than a sire effect.